relative weathering intensity of calcite versus dolomite in carbonate bearing temperate zone watersheds carbonate geochemistry and fluxes from catchments within the st lawrence and danube river basins 1 calcite and dolomite solubilities in open weathering environments are proportional to pco2 and inversely proportional to temperature and dolomite solubility is progressively greater than calcite below 25 c the continent scale weathering budget reveals the significance of the northern hemisphere nh to globally integrated riverine fluxes of ca2 mg2 and hco3 the nh contributes 70 of the global hco3 flux while only 54 of the riverine discharge we present results of a comparative hydrogeochemical study of carbonate mineral equilibria and weathering fluxes in two nh carbonate rich river basins surface water geochemistry and discharge were determined for headwater streams in michigan and slovenia within the st lawrence and danube river basins michigan watersheds are established atop carbonate bearing glacial drift deposits derived from erosion of paleozoic strata with thick soil horizons 100 300 cm slovenia watersheds drain mesozoic bedrock carbonates in alpine and dinaric karst environments with thin soil horizons 0 70 cm carbonate weathering intensity is a parameter that normalizes river runoff and hco3 concentration to catchment area meq hco3 km 2 s 1 summing calcite and dolomite contributions and is used to gauge the effects of climate land use and soil thickness on organic inorganic carbon processing rates importantly michigan riverine discharge is one tenth of slovenian rivers providing the opportunity to evaluate the kinetics of carbonate mineral equilibration the study rivers are hco3 ca2 mg2 waters supersaturated for calcite at pco2 values in excess of the atmosphere as discharge varies hco3 concentrations differ by less than 20 for any location and mg2 ca2 remains relatively fixed for michigan 0 5 and slovenia streams 0 4 requiring that dolomite dissolution exceed calcite on a mole basis the ability of calcite and dolomite dissolution to keep pace with increased discharge indicates carbonate weathering is limited only by water flux and temperature dependent solubility in these watersheds carbonate weathering intensity in michigan and slovenia exceeds the world average by factors between 2 and 20 and dolomite weathering intensity estimated from riverine mg2 fluxes exceeds the world average by factors between 2 and 15 thus global fluxes of carbonate related weathering products appear heavily skewed toward carbonate bearing environments at higher latitudes with relatively low mean annual temperatures and high discharge

geochemistry of speleothems affected by aragonite to calcite recrystallization potential inheritance from the precursor mineral abstract formerly aragonite speleothems recrystallized to calcite result from solutions subsaturated in aragonite and supersaturated in calcite that infiltrate into the speleothem through the interconnected porosity in most cases the crystal replacement takes place through a thin solution film this diagenetic process can occur under open or semi closed geochemical conditions thus secondary calcite crystals record the composition of the fluid at the time of diagenesis affected by calcite partition coefficients and fractionation factors open system or partly inherit the composition of the primary aragonite semi closed system so whether or not recrystallized aragonite speleothems can record reliable geochemical signals from the time of speleothem primary deposition still is an open debate we studied a stalagmite from eagle cave spain predominantly composed of secondary calcite that replaced aragonite although a core of primary aragonite extending 45 mm along the growth direction was preserved at the base of the sample we obtained mg and sr compositional maps paired u th dating and 18 o and 13 c profiles across the diagenetic front additionally two parallel isotope records were obtained along the speleothem growth direction in the aragonite and calcite sectors our results support that recrystallization of this speleothem took place in open system conditions for 18 o 13 c mg and sr but in semi closed system conditions for u and th the recrystallization of this sample took place during one or several events likely after the younger dryas as a result of climate change influencing drip water composition based on compositional zoned patterns we suggest that the advance of diagenetic fronts in this speleothem had an average rate of 50 45 m yr such recrystallization rate can transform any aragonite speleothem into calcite within a few centuries we suggest that the volume of water interacting with the speleothem at the time of recrystallization is of critical importance for inheritance of different elements the volume of solution is controlled by 1 the discharge of water passing through the sample and 2 the lapse time between aragonite dissolution and calcite precipitation hydrology and hydrochemistry of the interacting solution together with the mineralogy and texture of the speleothem are the essential controls for the diagenesis of the speleothem recrystallization of aragonite speleothems does not follow stratigraphical levels of the sample but occurs along sites with preferential flow paths in any sector of the speleothem in these cases the relationship between age and distance from base is not preserved however alternation of periods of recrystallization with periods of aragonite precipitation causing speleothem accretion can result in recrystallized speleothems with coherent distance from the base age relationship thus early diagenesis of speleothems affected by seasonal or inter annual oscillation of drip waters supersaturated and subsaturated in aragonite may provide best scenario conditions for dating and preservation of paleoenvironmental records along recrystallized speleothems however even in this scenario the variable discharge and the diagenetic rate control the geochemical inheritance from the primary aragonite crystals

the contribution to tectonic subsidence by groundwater abstraction in the pingtung area southwestern taiwan as determined by gps measurements abstract the three sets of global positioning system gps data collected from 1996 to 1999 are used to investigate the contribution to tectonic subsidence by groundwater abstraction in the pingtung plain southwestern taiwan the horizontal station velocities varied from 32 to 54 mm yr for azimuths ranging from 247 2 to 272 6 with respect to the permanent station s01r located in the penghu islands in the central and western part of the study area gps stations move generally towards the west whereas in the kaohsiung pingtung coastal area the displacement vectors demonstrate a clear counter clockwise deviation towards the sw the southern part of the offshore coastal area shows remarkable extension rates of 0 6 2 0 strain yr along azimuth 015 020 the significant southward increase of extensional strain rates is attributed to the lateral extrusion of blocks bounded by major discontinuities in the study area for the vertical movement the station velocities are from 13 to 25 mm yr significant subsidence rates from 11 to 25 mm yr have been observed these results clearly demonstrate the existence of transtensional deformation and the southward increase of extensional deformation in the along strike direction throughout the study area the comparison with the pattern of holocene subsidence rates and the isopach of fine grained sediments suggest that about 75 of this subsidence may result from the decrease in groundwater levels induced by over pumping these localized anthropogenic activities contributed to the natural risk that results from tectonic subsidence associated with tectonic extrusion and lateral extrusion at the southern tip of the taiwan collision belt

laboratory simulation of the wick effect in salt weathering of rock the wick effect is the upward migration of saline solutions into rocks and their subsequent crystallization lower carboniferous sandstone blocks of rectangular shape have been subjected to this process in the laboratory using a range of salt types a range of salt concentrations and various mixtures of salts some treatments produced severe disintegration notably sodium carbonate and a mixture of sodium carbonate with magnesium sulphate whereas other salts including sodium chloride and gypsum were much less effective the debris produced by this experimental salt weathering included appreciable quantities of silt sized material which were analysed with a laser granulometer such material could provide a source for desert loess

the nature and pattern of debris liberation by salt weathering a laboratory study a laboratory simulation of salt weathering was used to ascertain the effects of sodium sulphate and sodium carbonate under negev conditions using a single immersion technique three main points were addressed what are the grain size and textural characteristics of the debris liberated from limestones and a sandstone what do scanning electron microscope observations of the weathered samples tell us about the decay processes involved and how does the rate of debris liberation change during the course of 100 cycles the grain size characteristics of the liberated debris tended to be multimodal and were related to the original petrological characteristics of the rock large amounts of fines were produced which are believed to be analogous to the rock flour of arid areas blistering was also observed scanning electron microscope analysis revealed differences in the style of attack for different rock types and salt treatments and revealed the pattern of salt crystallization in pores and the nature of cracking the rate of debris liberation tended to decline or remain constant through time the reasons for this remain obscure but it is evident that diurnal cycles of temperature and humidity change can cause continuing rock weathering long after the initial input of salt to the rock has taken place

subsoil carbonate dissolution rates and their determining factors in a karst drainage basin sw china subsoil carbonate dissolution is the drives of atmosphere co2 consumption underground water alkalinity and karst landform specifically the determining factors and corresponding dissolution models for subsoil carbonate dissolution rate text r text carb remain under researched in various seasons and soil profiles in situ with standard limestone tablets they are the results of both ecosystem dynamics and hydrological processes thus this study aimed to explore text r text carb under different seasons soil depths and water drainage conditions in a karst drainage basin and reveal the factors determining them six hundred eighty four standard limestone tablets were exposed to fields in the subsoil of 10 cm 20 cm 30 cm and 40 cm deep sixteen plots five sites over every 3 to 4 months in a total of 423 days in the basin of the miaoguang underground river in southwest china the determining factors including soil co2 concentration moisture content temperature and ph were monitored at the same time the results are summarized in the following statements text r text carb ranged from 0 39 to 18 15 mg cm 2 a 1 were in a clear seasonal pattern principal component analysis pca of the observed soil factors revealed the mechanisms that in hot and rainy summer high text r text carb occurred in an open system with continuously supplemented co2 period i and decreased with rainfall amount period iv low text r text carb occurred in a closed system with inactive biological co2 production under cold weather period ii and iii hence as soil temperature decreased text r text carb increased text r text carb increased with soil depths as the elevated soil co2 temperature and available acid water dissolution occurred in an open system on an annual average scale and a well fitting equation of text r text carb and soil factors were given local water drainage was critical in carbonate chemical dissolving with implications of formations of local karst landform due to no or less groundwater drain and spring seepage text r text carb measured in site b a flat saddle with underlying dolomite bedrock was nearly zero conversely with water retention text r text carb was higher in gentle limestone hillslope or depression than in steep hillside because of longer water rock interaction duration in general in karst drainage basin areas text r text carb was determined by multiple factors about seasons soil depths and water drainage

five year measurements of rock tablet weathering on a forested hillslope in a humid temperate region in order to elucidate the effects of rock type and geomorphic setting on weathering rates field experiments using microweight loss techniques were carried out rock tablets for eight kinds of rock types granite granodiorite gabbro limestone andesite rhyolite crystalline schist and tuff with a diameter of 3 5 cm and a thickness of about 1 cm were enclosed in a nylon mesh bag and placed in the four corners of a soil bedrock interface on a granodiorite hillslope of central japan for over 5 years the results show that 1 the saturated grus layer is the main locus of solutional denudation 2 the 18 and 11 weight losses of limestone and tuff under a saturated soil layer were clearly the largest of all the rock types examined and 3 the weight loss is smaller for granite gabbro crystalline schist and andesite while it is larger for tuff and rhyolite at every location these results suggest that weathering rates are influenced by both lithology and environmental conditions

four climate cycles of recurring deep and surface water destabilizations on the iberian margin centennial climate variability over the last ice age exhibits clear bipolar behavior high resolution analyses of marine sediment cores from the iberian margin trace a number of associated changes simultaneously proxies of sea surface temperature and water mass distribution as well as relative biomarker content demonstrate that this typical north south coupling was pervasive for the cold phases of climate during the past 420 000 years cold episodes after relatively warm and largely ice free periods occurred when the predominance of deep water formation changed from northern to southern sources these results reinforce the connection between rapid climate changes at mediterranean latitudes and century to millennial variability in northern and southern polar regions

rock slope instability and erosion toward improved process understanding rock slopes in a range of environments are among the landscape elements most sensitive to climate change the latter affecting rock mass properties altering slope boundary conditions and changing geosystem configurations major climate dependent influences promoting destabilization include stress redistribution with changing glacial ice extents degradation of mountain permafrost altered slope hydrology and weathering environments loading and unloading due to deposition and erosion and changes in the spectrum of magnitude and frequency of driving forces in steep bedrock terrain erosional processes control slope morphology by modulating rates of i weathering in response to climate and pre disposition ii rock slope retreat in response to magnitude and frequency of detachment and iii channel incision or valley infilling in response to variable sediment supply modelling landscape evolution and anticipating natural hazards in these environments thus requires deeper insights into the processes driving rock slope instability and erosion this special issue emphasizes new understanding of rock slope processes through a collection of manuscripts at the forefront of research in the field copyright 2014 john wiley sons ltd

surface lowering rates of uplifted limestone terraces estimated from the height of pedestals on a subtropical island of japan in kikai jima south western japan many pedestal rocks have developed on the surface of holocene raised coral reef terraces with known dates of emergence pedestals are formed just under boulders which are considered to have been transported by tsunami and settled on a reef flat before emergence on the assumption that boulders protect the underlying limestone terrace from rainfall solution the rate of surface lowering of these limestone terraces was evaluated from the height of pedestals and the period of their formation the result showed that the mean lowering rate over 6000 years is 205 mm ky copyright 2007 john wiley sons ltd

organic geochemical characteristics and depositional environment of the tertiary tanjong formation coals in the pinangah area onshore sabah malaysia article i nfo article history the tertiary tanjong formation coals exposed in the west middle block of the pinangah coalfield central part of southern sabah were analyzed and their depositional environments were interpreted the tertiary tanjong coals are humic and generally dominated by vitrinite with significant amounts of liptinite and low amounts of inertinite macerals total organic carbon contents toc of the coals range from 51 2 to 77 7 wt and yield of bitumen values ranging from 57 300 to 140 000 ppm which meet the standard as a source rock with good hydrocarbon generative potential in support good liquid hydrocarbons generation potential can be expected from the tanjong coals based on significant liptinitic content 15 this is supported by their high hydrogen index up to 300 mg hc g toc consistent with type ii and mixed type ii iii kerogens and py gc s2 pyrograms with n alkane alkene doublets extending beyond c30 the coal samples have vitrinite reflectance values in the range of 0 42 0 66 ro indicating immature to early mature stage for hydrocarbon generation these vitrinite reflectance values also indicated that the tanjong coals are with sub bituminous b a and high volatile bituminous c rank tmax values ranging from 419 to 451 c are good agreement with the vitrinite reflectance data this is supported by biomarker maturity parameters as suggested by the c32 homohopane the saturated fraction of the tanjong coals are characterized by dominant odd carbon numbered n alkanes n c23 to n c33 high pr ph ratios 8 18 high tm ts ratios 6 28 and pre dominant of regular sterane c29 all biomarker parameters clearly indicate that the organic matter was de rived from terrestrial inputs and deposited under oxic condition

a global review of solutional weathering forms on quartz sandstones abstract solutional landforms in limestone have been described for over a hundred years but landforms of similar morphology on highly siliceous sandstones and quartzites have also been identified in a wide variety of environments and generally termed pseudokarst these include large bedrock pinnacles and towers caves corridors grikes solution basins and runnels and even silica speleothems quartzites and quartz sandstones have been held to be amongst the most chemically resistant of rocks but the similarity both in morphology and genetic process of many landforms developed from them to features of known solutional origin on limestone has prompted some authors to refer to these quartzose landforms as true karst the most detailed studies of quartzose karst landforms have been in present day tropical regions or areas believed to have been tropical in the geologically recent past this concentration of research in hot wet areas allied with the long held assertion of the insolubility of silica especially quartz has led to a belief that tropical climatic conditions are necessary for karstic solution of these rocks however the existence of quartzose karst landforms in temperate and even sub polar latitudes especially where there is no evidence of prior tropical conditions suggests that the requirement of tropical weathering is no longer tenable the reports of these quartzose solutional landforms are widely scattered through the geomorphological and geological literature but a comprehensive world wide review of the range of solutional landforms on quartzose rocks has not previously been published because of the increasing awareness in this karst type such a summary is sorely overdue

weathering rinds and rock coatings from an arctic alpine environment northern scandinavia coarse rock debris exposed in the subaerial environment of northern sweden displays the development of a wide variety of surface coatings these include weathering rinds as well as a great diversity of geochemical coatings including those dominated by ca fe si and al each of these types of rock coatings displays a high degree of geochemical complexity the weathering rinds exhibit both geochemical and morphologic changes to the parent rock cores including extensive dissolution oxidation and hydration as well as disaggregation fracturing and cementation by secondary geochemical coatings chemical breakdown of the rock to form weathering rinds includes loss of k si mg and ca and buildup of fe weathering rinds are fundamentally the result of dissolution as no clay minerals were identified in the rinds rock coatings are distinguished from rinds by their clear accretionary nature despite the distinction made between weathering rinds and rock coatings it is important to note that often the two are intimately related the presence of rock coatings as well as weathering rinds on rock surfaces amplifies the important role played by geochemical processes in the arctic alpine climate of northern sweden in particular as well as its significance in landscape evolution in such environments in general

organic facies and depositional palaeoenvironment of lignites from rio maior basin portugal abstract the rio maior basin portugal is a tectonic depression filled by a pliocene sequence that comprises from floor to roof i kaoliniferous fine sands ii diatomites and lignites iii recent deposits of sandstone and clay the diatomites and lignites form a small dissimetric syncline with alternating seams ten lignite seams were identified and named from floor to roof as f e d c 2 c 1 c b a a and a seams a d e and f are considered to be the main seams the organic fraction consists mainly of macerals of the huminite group with small percentages of inertinite and liptinite groups however the petrographic composition of each seam is distinct particularly with regards to macerals of the huminite and liptinite groups calculation of petrographic indices permitted to plot the coals in facies and palaeoenvironment diagrams five facies have been defined i aquatic ii herbaceous swamp iii mixed swamp with forest and herbaceous vegetation vi forest swamp wetter and v forest swamp drier these lignites are humic coals formed from organic matter of terrestrial origin the peat biomass at the origin of these coals formed from a very diverse vegetation comprising gymnosperms and angiosperms in seams f and occasionally in seams e and d botryococcus algae have also contributed to the biomass peat deposition corresponded to a rheotrophic hydrological regime the water level always remained above the topographic surface of the basin nevertheless during the deposition of seam a in the northern part of the basin the water level was slightly below the topographic surface the organic matter was preserved in anaeorobic conditions

weathering instability and landscape evolution abstract the argument in this paper is that the fundamental control on landscape evolution in erosional landscapes is weathering the possibility of and evidence for instability in weathering at four scales is examined the four scales are concerned with weathering processes allocation of weathered products the interrelations of weathering and denudation and the topographic and isostatic responses to weathering limited denudation the regolith hillslope landscape unit and landscape scales respectively the stability conditions for each model and the circumstances under which the models themselves are relevant are used to identify scale related domains of stability and instability at the regolith scale the interactions among weathering rates resistance and moisture are unstable but there are circumstances over long timescales and where weathering is well advanced under which the instability is irrelevant at the hillslope scale the system is stable when denudation is transport rather than weathering limited and where no renewal of exposure via regolith stripping occurs at the level of landscape units the stability model is based entirely on the mutual reinforcements of weathering and erosion while this should generally lead to instability the model would be stable where other external controls of both weathering and erosion rates are stronger than the weathering erosion feedbacks at the broadest landscape scale the inclusion of isostatic responses destabilizes erosion topography uplift relationships thus if the spatial or temporal scale is such that isostatic responses are not relevant the system may be stable essentially instability is prevalent at local spatial scales at all but the longest timescales stability at intermediate spatial scales is contingent on whether weathering erosion feedbacks are strong or weak with stability being more likely at shorter and less likely at longer timescales at the broadest spatial scales instability is likely although stability may be present at intermediate temporal scales if weathering erosion feedbacks are weak the distinction is important because stability is associated with convergent evolution whereby the effects of initial variations or disturbances are reduced over time as the landscape converges toward a stable equilibrium state instability by contrast indicates divergent evolution increasing differentiation over time and the persistence and growth of disturbance effects and initial variations

tortoises and hares dissolution erosion and isostasy in landscape evolution denudation mechanisms differ fundamentally between limestone and silicate rock types which are subject to very different rate thresholds and enhancers inhibitors silicates are removed largely by erosion the mechanical entrainment and transport of particles this is a relatively high energy and highly episodic process which occurs only when a minimum threshold flow velocity is exceeded it is inhibited by vegetation cover and favoured by strongly seasonal runoff limestone is removed largely by chemical dissolution at a rate directly proportional to runoff dissolution is a relatively low energy process that can occur at any flow velocity or in static water in general it is enhanced by vegetation cover and non seasonality of runoff these contrasting factors in the denudation of silicates versus limestone can produce strikingly uneven rates of surface lowering across a landscape sometimes akin to the well known tortoise and hare race where the slow and steady denudation of limestones may in the long term exceed the sometimes rapid but often localized and episodic erosion of silicates prolonged exposure of limestone to a humid temperate climate in a tectonically stable environment produces lowrelief corrosion plains in which limestone uplands are anomalous and in most instances due to recent unroofing from beneath a siliciclastic cover in a highly seasonal or semi arid climate almost the exact inverse may develop with flashy runoff and sparse vegetation favouring erosion rather than dissolution even under a constant humid climate progressive unroofing of a thick limestone unit within folded siliciclastics may lead to a topographic inversion over time with the limestone outcrop always forming a topographic low flanked by siliciclastic uplands valleys will be initiated on anticlinal crests where the limestone is first unroofed but progressive lowering of the limestone causes these valleys to migrate to their final position in the synclinal troughs in humid climates isostatic compensation in response to slow but continuous denudation of extensive limestone outcrops may be a significant factor in the development of relief on adjacent more slowly eroding silicate outcrops copyright 2004 john wiley sons ltd

hydrocarbon potential of pennsylvanian coal in bohai gulf basin eastern china as revealed by hydrous pyrolysis abstract a hydrous pyrolysis experiment was performed using pennsylvanian brown coal with a vitrinite reflectance vr 0 of 0 56 from a coal mine at the southwest corner of the bohai gulf basin eastern china to evaluate the hydrocarbon potential of the coal the coal sample is vitrinite rich 74 5 and inertinite poor 16 7 with liptinite content of 8 8 much of the vitrinite in the sample consists of hydrogen rich vitrinite collodetrinite hydrous pyrolysis was performed at 200 c 230 c 260 c 290 c 320 c and 350 c for 72 h separately yields of both total liquid pyrolysates and expelled oil increased with temperature before reaching their maximum production of 17 27 kg t coal and 14 57 kg t coal at the same temperature of 320 c vr 0 1 18 and decreased afterwards gaseous products increased sharply at 320 c and tended to increase even at the highest experimental temperature 350 c vr 0 1 53 results show that the coal has not only a certain oil generation potential but also a large capacity for gas production and a high expulsion efficiency oil potential of the coal is attributed to its depositional environment which was transitional from shallow marine to coastal plain or swamp during middle to late pennsylvanian the coal was protected from oxidation under water after deposition experimental results indicate that this pennsylvanian coal could have contributed to oil gas accumulation in the bohai gulf basin

lithologic and climatologic controls of river chemistry abstract the chemistries of rivers draining a variety of lithologic and climatic regions have been surveyed for the purpose of quantifying the fluxes of bicarbonate and silica from rivers with respect to bedrock lithology and runoff in all 101 different rivers each draining a primary lithology were examined across the united states puerto rico and iceland to minimize seasonal effects only rivers with at least two years of data were used basaltic catchments were examined in the greatest detail in a survey of hawaiian island watersheds the average river chemistries could be related to the distribution of soil associations within each catchment an analysis of cation activity relationships among rivers draining basaltic catchments shows that the river compositions define slopes which are consistent with an equilibrium ion exchange control on cation ratios among different lithologies unique weathering rate relationships were developed with yields at typical present day runoff rates 1 100 cm y increasing in the order sandstones granites basalts shales and carbonates the bicarbonate and silica fluxes for each of these lithologies have been quantified for use in global studies of chemical denudation our study confirms that the dissolved yield of a given drainage basin is determined by a balance between physical and chemical weathering thus a warm wet climate or the presence of abundant vegetation cannot guarantee high rates of chemical denudation unless accompanied by high rates of physical removal

styles and rates of long term denudation in carbonate terrains under a mediterranean to hyper arid climatic gradient abstract carbonate minerals unlike silicates have the potential to dissolve almost completely and with high efficiency thus in carbonate terrains denudation rate and style the governing process of denudation mechanical or chemical should be more sensitive to climatic forcing using 36 cl measurements in 39 carbonate bedrock and sediment samples we calculate long term denudation rates across a sharp climatic gradient from mediterranean to hyper arid conditions our samples were collected along the arugot watershed which drains the eastern flank of the judea range central israel to the dead sea and is characterized by a pronounced rain shadow denudation rates of flat lying bedrock outcrops sampled along interfluves differ by an order of magnitude from 20 mm ka 1 in the mediterranean zone to 1 3 mm ka 1 in the hyper arid zone these rates are strongly correlated with precipitation and thus reflect the importance of carbonate mineral dissolution in the overall denudation process in contrast denudation rates of steep bedrock surfaces depend on the hillslope gradient but only in the hyper arid climate zone indicating that mechanical processes dominate the overall hillslope denudation within this zone the dominance of slope dependent mechanical erosion in the hyper arid zone is also reflected by an increase in spatially average denudation rates from 17 19 mm ka 1 in the mediterranean semi arid zones to 21 25 mm ka 1 in the hyper arid zone these higher rates are attributed to clast contribution from steep slopes under arid climate this suggests an increased importance of mechanical processes to the overall denudation in the hyper arid zone we demonstrate that the transition between chemically dominated denudation to mechanically dominated denudation occurs between 100 and 200 mm of mean annual precipitation long term denudation rates across the judea range indicate that between mediterranean and hyper arid climates chemical weathering rates are limited by precipitation nevertheless in more humid climates chemical weathering rates are apparently limited by the rates of carbonate mineral dissolution this study demonstrates that carbonate terrains have the capacity to shift between mechanically and chemically dominated denudation in response to changes in precipitation similar transitions in response to changes in temperature or the level of tectonic activity have been previously reported we suggest that the abrupt nature of such transitions can be primarily attributed to the efficiency of carbonate dissolution processes and the competition between surface and subsurface drainage systems in carbonate terrains

comparison between coastal and inland karst limestone lowering rates in the northeastern adriatic region italy and croatia a comparison among lowering rates collected in the limestones of the northeastern adriatic region italy and croatia gives a picture of the erosion patterns in the inland and coastal classical karst and istrian karst erosion rates were measured using either a micro erosion meter or a traversing micro erosion meter beginning from a large dataset spread over a maximum of 26 years significant differences in limestone lowering rates have been recognized in the surveyed area the mean lowering rate for the inland classical karst area is 0 018 mm yr whereas in the inland istrian karst it is 0 009 mm yr in the coastal sectors the mean erosion rate varies between 0 14 mm yr in the gulf of trieste and 0 04 mm yr in the sites located along the istrian shoreline these differences are probably due to the climatic setting of the classical karst area mediterranean continental to sub alpine climate and istrian peninsula mediterranean climate moreover along the coasts of the gulf of trieste there are many submarine springs which are absent along the istrian coast it is hypothesized that these underwater springs stress the effect of rainfall along the coast which is both direct rain on the measurement site and mainly indirect freshwater outflow from submarine springs higher lowering rates were surveyed during autumn rainfall therefore also freshwater outflow from submarine springs is particularly high at the end of the summer and in autumn

surface temperature differences between minerals in crystalline rocks implications for granular disaggregation of granites through thermal fatigue thermal expansion differences between minerals within rocks under insolation have previously been assumed to drive breakdown by means of granular disaggregation however there have been no definitive demonstrations of the efficacy of this weathering mechanism different surface temperatures between minerals should magnify thermal expansion differences and thus subject adjacent minerals to repeated stresses that might cause breakdown through fatigue failure this work confirms the existence of surface temperature differences between minerals in granitic rocks under simulated short term temperature fluctuations so as to discriminate their potential for initiating granular disaggregation the influence of colour as a surrogate for albedo and crystal size as a function of thermal mass are specifically identified because of their ease of quantification four rock types with a range of these properties were examined and subjected to repeated short term temperature cycles by radiative heating and cooling under laboratory conditions results show that while albedo is the main control for overall and individual maximum temperatures crystal size is the main factor controlling higher temperature differences between minerals thus stones with large differences of mineral sizes can undergo magnified stresses due to thermal expansion differences

controls on denudation rates in tectonically stable mediterranean carbonate terrain using cosmogenic isotopes and solute load analysis we quantify chemical weathering solutional erosion and denudation rates over variable time scales in a tectonically stable moderate relief carbonate terrain soreq drainage judea hills israel located in a semihumid mediterranean climate long term 10 4 yr denudation rates were calculated from 36 cl concentrations in 51 bedrock and sediment samples bedrock samples range in elevation 340 850 m hillslope gradient 0 30 and mean annual precipitation map 500 630 mm and vary in soil cover thickness 0 75 cm mg ca ratio 0 0 1 0 mol clay mineral contents 0 6 wt and mechanical strength 41 58 schmidt hammer rebound units soil pco2 values at a single location during the course of 1 yr range between 0 4 and 9 0 mmol mol 1 average long term denudation rate of exposed bedrock samples is 21 7 mm k y 1 field observations and 36 cl measurements indicate that soil pockets undergo cycles in the rate of deepening and that over 10 5 yr time scale average denudation rates beneath soil pockets are similar to those of exposed bedrock sediment samples yield even higher denudation rates which are probably anthropogenically induced but could also indicate that the sediment source is soil pockets long term denudation rates are decoupled from hillslope gradient elevation and rock strength denudation rates show a positive correlation with present day map values exhibit a complex relation with rock mg content and show a weak correlation with clay content annual chemical weathering rates were calculated from modern day solute load measured in waters of perched springs and the regional carbonate aquifer our results indicate that on annual decadal and 10 4 yr time scales chemical weathering and denudation are controlled by carbonate dissolution while mechanical processes are far less signifi cant overlap between the distributions of hco3 concentrations measured in runoff springs and the regional aquifer water suggests that chemical weathering focuses at the bedrock surface and therefore is comparable with solutional denudation this result is in contrast to the features of ancient fl uvial and colluvial activity steep nonconcave hillslopes and stream profi les and knickzones in the streams preserved in the present landscape such features were formed in response to mid pleistocene uplift and could have been preserved due to a decrease in stream power following the formation of subsurface drainage and the lowering in abrasive clast supply that followed the stabilization of hillslopes in the drainage long term denudation rates calculated from exposed bedrock samples are higher by factor of 1 4 relative to annual contemporary chemical weathering rates increased precipitation by a similar factor averaged over the last glacial and present interglacial can explain this difference

complex weathering in drylands implications of stress history for rock debris breakdown and sediment release abstract weathering studies have often sought to explain features in terms of a prevailing set of environmental conditions however it is clear that in most present day hot desert regions the surface rock debris has been exposed to a range of weathering environments and processes these different weathering conditions can arise in two ways either from the effects of long term climate change acting on debris that remains relatively static within the landscape or through the spatial relocation of debris from high to low altitude consequently each fragment of rock may contain a unique weathering related legacy of damage and alteration a legacy that may greatly influence its response to present day weathering activity experiments are described in which blocks of limestone sandstone granite and basalt are given stress histories by subjecting them to varying numbers of heating and freezing cycles as a form of pre treatment these imposed stress histories act as proxies for a weathering history some blocks were used in a laboratory salt weathering simulation study while others underwent a 2 year field exposure trial at high mid and low altitude sites in death valley california weight loss and ultrasonic pulse velocity measurements suggest that blocks with stress histories deteriorate more rapidly than unstressed samples of the same rock type exposed to the same environmental conditions laboratory data also indicate that the result of imposing a known weathering history on samples by pre stressing them is an increase in the amount of fine sediment released during salt weathering over a given period of time in comparison to unstressed samples

incipient weathering rind development on introduced machine polished granite discs in an arctic alpine environment northern scandinavia weathering rinds zones of alteration on the exterior surfaces of rock outcrops and coarse unconsolidated surficial debris are widely used by geomorphologists and quaternary geologists as indicators of the relative age of landforms and landscapes additionally they provide unique insights into the earliest stages of rock and mineral weathering yet the origin of these alteration zones is relatively poorly understood this lack of understanding applies especially to the initial stages of rind formation the study reported in this paper has two principal objectives the first is to use lightly polished granite discs inserted in soil profiles under several different plant communities in an arctic alpine environment for a period of four or five years to investigate the nature of incipient weathering rind development the second is to investigate the factors responsible for spatial variability in the nature and rates of rind formation incipient weathering rind development on the outer edges of the granite discs is observable and measurable over a period of time as short as four years in the mild arctic alpine environment of swedish lapland the earliest stages of rind development involve the development of a porous structure consisting of a combination of pits and fractures which have been solutionally enlarged and modified solution appears to be preferentially concentrated on the surfaces of feldspars and to a lesser extent quartz in addition iron oxides are present along grain boundaries and in grain interiors and are interpreted to have been derived from the oxidation of ferromagnesian minerals spatial variability in weathering rind development appears to be particularly driven by differences in moisture but is not related to soil ph copyright 2005 john wiley sons ltd

linking weathering and rock slope instability non linear perspectives weathering is linked complexly to the erosion and evolution of rock slopes weathering influences both the strength of rock slopes and the stresses that act upon them while weathering has often been portrayed in an over simplified way by those studying rock slope instability in reality it consists of multiple processes acting over different spatial and temporal scales with many complex inter linkages through a demonstration of the sources of non linearities in rock slope weathering systems and their implications for rock slope instability this paper proposes five key linkages worthy of further study copyright 2012 john wiley sons ltd

factors controlling carbonate dissolution rates quantified in a field test in the austrian alps carbonate dissolution rates were investigated by measuring the mass difference of carbonate tablets exposed to natural dissolution for 1 year 70 tablets were distributed over 13 test sites on the north slope of the hochschwab massif in the austrian alps the influences of altitude subsoil vs sub aerial exposure vegetation karst morphology soil humidity sample lithology and sample surface morphology were investigated the observed dissolution rates varied between 13 and 40 m a for subcutaneous samples and about 11 m a for sub aerial exposure outstandingly high rates of 48 m a were observed in a doline and nearly zero rates were measured at a site influenced by seeping spring water a mass balance using high resolution hydrological data was calculated for the klaffer spring which has an average outflow of 4 8 m3 s it indicated a loss of 21 106 kg of carbonate rock per year which gives an average dissolution rate of 95 m a for the catchment area of 83 km2 the dissolution rates of 10 m a from the sub aerially exposed samples are comparable to values from limestone pedestals which were protected from dissolution by glacial erratics for the past 15 ka

petrology palynology coal facies and depositional environments of an upper carboniferous coal seam minto coalfield new brunswick canada coal petrology and palynology of the minto coal seam enable depositional environments of the precursor mire to be established in terms of facies critical maceral ratios maceral assemblages and spore and pollen assemblages the overall petrographic composition indicates a vitrinite rich coal mean 67 followed by inertinite mean 27 and liptinite mean 7 pyrite is common to abundant maximum 15 lithotype logs demonstrate a dominance of dull lithotypes dull and banded dull petrographic composition at the lithotype and seam subsection level is highly variable vitrinite maceral assemblages are enriched in brighter lithotypes banded bright and bright whereas liptinite and inertinite maceral assemblages are enriched in dull and banded dull lithotypes the duller lithotypes are enriched by mineral matter based on spores the seam is assigned to the vestispora zone of atlantic canada with the basal torispora securis torispora laevigata sl zone of western europe and the lower torispora secur

weathering grade of rock masses as a predisposing factor to slope instabilities reconnaissance and control procedures weathering of rock masses often assumes importance as a predisposing factor to slope instability and it is possible to map it at various scales depending on the different purposes the effects of weathering processes are particularly intense on crystalline rocks plutonic and metamorphic these rocks are present in large areas of the globe and widespread in calabria the relationships between rock mass weathering grades and slope instabilities are analysed with reference to sectors 1 50 000 scale and areas 1 10 000 scale where crystalline rocks are strongly affected by weathering to this aim a reconnaissance procedure has been proposed to delimitate the zones with different weathering condition three macro classes at average scale 1 50 000 and six classes at detail scale 1 10 000 in this procedure first analysis of aerial photos and then field observations of representative situations have been used the reconnaissance procedure has been verified in a selected study area acri whose geological features are provided by the comparison with weathering maps obtained by means of a control procedure this last procedure consists of observations and index tests carried out in check points located in representative check sites discolouration sound when struck by geological hammer effect of the point of geological pick breaking with the hands rebound of schmidt hammer grain size analysis the results obtained confirm through quantitative data that the weathering of a rock mass can be assumed as a predisposing factor to slope instability at average scale 1 50 000 the reconnaissance procedure is able to give weathering maps representative for this type of evaluation the ratio between the landslides area in each weathering macro class and the whole landslide area goes from 67 to 14 for the macro class a and from 24 to 9 for the macro class b at detail scale 1 10 000 it is necessary to use a control procedure to obtain weathering maps indicative of predisposition to slope instabilities

limestone weathering rates accelerated by micron scale grain detachment the weathering of carbonate rocks plays a critical role in the evolution of landscapes the erosion of buildings and monuments and the global scale shifting of carbon from the atmosphere to the ocean chemical dissolution is often assumed to govern the rates of weathering of carbonate rocks although some studies have suggested that mechanical erosion could also play an important role quantifying the rates of the different processes has proved challenging in part due to the high degree of variability encountered across different scales in both field and laboratory conditions to constrain the rates and mechanisms controlling long term limestone weathering we analyze a lidar scan of the western wall a roman period edifice located in jerusalem we find that extreme erosion rates in fine grained micritic limestone blocks are as much as two orders of magnitude higher than the average rates estimated for coarse grained limestone blocks at the same site atomic force microscope imaging of dissolving micritic limestone suggests that these elevated reaction rates are likely to be the result of rapid dissolution along micron scale grain boundaries followed by mechanical detachment of tiny particles from the surface our analysis indicates that such grain detachment could be the dominant erosional mode for fine grained carbonate rocks in many regions on earth

understanding the ancient habitats of the last interglacial late mis 5 neanderthals of central iberia paleoenvironmental and taphonomic evidence from the cueva del camino spain site the cueva del camino site pinilla del valle madrid represents the most complete mis 5 record from the iberian peninsula away from the mediterranean margin including a large accumulation of fossilized remains of small and large vertebrates and two human teeth the presence of carnivores mainly hyenas and humans suggests that the site should be interpreted as a spotted hyena den a human occupation or both during an earlier phase of excavation undertaken during the 1980s an anthropic origin was suggested for the accumulation at the site however research was resumed in 2002 leading to an increase in the number of vertebrate remains recovered as well as the recognition of new vertebrate species these have now been incorporated into the site s list of fauna in addition new palaeobotanical geochronological and stratigraphic data have been recorded and analysed and the human teeth identified as being of neanderthal origin floristic data pollen and charcoal remains obtained for the north sector of this site indicate an open landscape with pinus sylvestris nigra as the main arboreal taxon the available evidence suggests this accumulation to be the result of spotted hyena activity during a warm phase of marine isotope stage 5 mis 5 in an environment in which fallow deer was the most abundant herbivore

reconstruction of cave air temperature based on surface atmosphere temperature and vegetation changes implications for speleothem palaeoclimate records abstract cave temperature is a parameter of major importance for palaeoclimate studies based on speleothems since most proxies used are temperature dependent the general assumption that cave temperature reflects the mean annual surface atmosphere temperature sat over the cave is based on a limited number of specific studies and detailed mechanisms supporting this link are not properly described eagle cave in spain was used to understand the detailed mechanisms connecting sat and cave temperature a monitoring programme conducted from 2009 to 2011 allows the characterization of the thermal dynamics in the cave air in the studied karstic environment thermal conduction is the main mechanism responsible for transferring the ground temperature signal to the cave the calculated thermal diffusion coefficient is 0 756 10 6 0 013 m 2 s 1 the sat signal is recorded at the cave with a delay ranging from 3 to 11 yr depending on the thickness of the bedrock over the ceiling 5 18 m a cave cooling of 2 c has been recorded since mid 1970s when cave temperature measurements were made the application of a model exclusively based on thermal conduction of sat does not reproduce the observed thermal changes however vegetation cover over the cave was modified dramatically during recent decades this impacts ground temperature due to the changes in exposure to insolation and the modification of soil properties which is eventually recorded in the cave the incorporation of changes in vegetation cover in the model provides a realistic thermal reconstruction the impact of vegetation cover was much more significant than sat in order to explain the large thermal change in the cave over past decades thus the cooling in eagle cave during past decades is mainly controlled by a variable decoupling from mean annual sat as a result of the afforestation over the cave the effect of this thermal decoupling on speleothem 18 o records is potentially significant and should be considered when performing accurate palaeoclimate reconstructions

field and laboratory experiments on high dissolution rates of limestone in stream flow abstract field and laboratory experiments were performed to examine dissolution rates of limestone in stream flow field experiments were conducted in three stream sites a c with different lithological or hydrological settings around a limestone plateau in the abukuma mts japan sites a and b are allogenic streams which flow from non limestone sources into dolines and site c has a karst spring source tablets made of limestone from the same plateau with a diameter of 3 5 cm and a thickness of 1 cm were placed in the streams for 3 years 2008 2011 where alkalinity ph and major cation concentrations were measured periodically the saturation indices of calcite sic of stream water were 2 8 0 4 at site a 2 5 0 4 at site b and 0 5 0 4 at site c annual weight loss ratios for tablets were extremely high at site a 0 11 0 14 mg cm 2 d 1 high at site b 0 05 mg cm 2 d 1 and low at site c 0 005 mg cm 2 d 1 the contrasting rates of weight loss are mainly explained by chemical conditions of stream water in addition laboratory experiments for dissolution of limestone tablets using a flow through apparatus revealed that flow conditions around the limestone tablet is another important factor for dissolution in the stream environment these results revealed that limestone dissolves at a rapid rate where water unsaturated to calcite continuously flows such as in an allogenic stream

numerical models for mixing corrosion in natural and artificial karst environments 1 the enlargement of initially small fractures in a karst aquifer by chemical dissolution is studied flow in the aquifer is driven by head differences between sinks and resurgences and flow depends on the permeability of small fissures and fractures in the aquifer enlargement of fractures is controlled by the chemical composition of the recharge as water undersaturated with respect to calcite is able to dissolve material from the fracture walls as fractures are enlarged with time permeability within the aquifer increases significantly and flow becomes very heterogeneous two different processes are considered enlargement due to normal corrosion where water is undersaturated with respect to calcite and enlargement due to mixing corrosion where two solutions saturated with respect to calcite but with different carbon dioxide concentrations mix and the resulting solution becomes undersaturated again the importance of mixing corrosion is discussed for two boundary conditions a natural karst aquifer is modeled with fixed recharge boundary conditions representing sinking streams and an artificial karst aquifer is simulated with fixed head boundary conditions representing a reservoir in both cases mixing corrosion is important especially if recharge is characterized by an almost saturated chemistry mixing corrosion significantly changes the evolving passage pattern as dissolution due to mixing of solutions is possible deep in the aquifer mixing corrosion also reduces breakthrough times of the aquifer and can result in dramatic leakage underneath dam sites even if the impounded water is almost saturated with respect to calcite

ten years 1994 2004 of potential weathering in karkevagge swedish lapland this paper reports the findings of a ten year study of potential weathering of machine polished dolomite granite and limestone discs buried in shallow pits beneath a variety of vegetation cover types in karkevagge and on an adjoining ridge in swedish lapland the paper extends a previously published five year 1994 1999 record by adding the period 1999 2004 comparing the two periods and integrating results to provide a decadal record the field and laboratory procedures of the first period were faithfully replicated during the second period with the notable modification that only a segment of each original disc was replaced in the field for the second portion of the study a total of 48 dolomite 36 granite and 19 limestone discs were buried at shallow depths 60 cm beneath alpine tundra birch forest dryas heath heath meadow solifluction meadow and willow cover types with the exception of the willow which had only two each cover type had three replicated pits relationships identified during period 1 were generally repeated during period 2 salient results are the expected weathering rate order of limestone dolomite granite and statistically distinguishable differences in weathering rate by vegetation cover type differentiation of the two heath categories from the other vegetation cover types is the most important spatial distinction in weathering rate statistical distinctions among other measures were variable with soil horizon and burial depth being non significant ph variability being weakly distinguishable and drainage variability being important granite mass losses were generally too low to be useful for statistical separation dolomite discs experienced a statically higher loss rate during period 2 which had both a warmer and wetter air climate than period 1 minimum and maximum total decadal percentage losses from the discs were 0 2 and 25 7 for dolomite 0 07 and 0 57 for granite and 0 2 and 32 1 for limestone in general dolomite was the most useful material for monitoring mass loss with limestone weathering tending to be too rapid and granite weathering being too slow copyright 2006 john wiley sons ltd

a review of the tagus river tufa deposits central spain age and palaeoenvironmental record here we determined the aminostratigraphy and aminochronology of tufa deposits located in central spain associated w i t h the tagus river and some o f its tributaries the henares dulce cifuentes ruguilla trabaque escabas and guadiela rivers w e used aspartic acid and glutamic acid racemization ratios obtained from the ostracod herpetocypris reptans tufa accumulations were found to be of different origins those in t h e henares cifuentes and ruguilla rivers are of paludal origin w h i l e those in t h e dulce and tagus rivers are o f fluvial origin a generally g o o d correspondence was found b e t w e e n the age o f the deposits and the position of the terraces above the current thalweg however the geomorphological evolution of the henares cifuentes and ruguilla rivers infilling of pre existing valleys has produced deposits of distinct ages at the same elevation above the current river thalweg and sometimes older tufas are located b e l ow younger ones we distinguished eight main tufa deposition episodes these occurred predominantly during even marine isotopic stages mis at 4 0 6 90 mis 11 2 6 4 68 mis 7e 189 4 0 mis 7a 130 27 mis 6 5e 101 2 5 mis 5c 3 2 10 mis 3 1 4 4 mis 1 a n d 6 2 mis l k a these results are in agreement w i t h the dating of similar deposits from nearby areas and other zones of s p a i n a n d europe the tufa stable isotope compositions were similar to other examples in central and southern spain a n d their plot falls in the same field as other lowland european stream tufas o x y g e n stable isotopes were influenced mainly b y temperature a n d rainfall the 51 3c values indicated a major effect o f soil derived carbon rather t h a n carbon from the catchment area but moderated in each tributary b y evaporation flow regime and biological effects photosynthesis

current denudation rates in dolostone karst from central spain implications for the formation of unroofed caves abstract rock tablets of known weight were buried in the soil of a karst region in central spain to evaluate the carbonate weathering during a period of a year the experiment was conducted at two different soil depths 5 10 and 50 55 cm from the surface the parental rock used in the experiment is composed of dolomite and magnesite with variable proportion of accessory minerals and minor elements soil mineral and chemical composition as well as its texture was also characterized meteorological conditions at the site together with temperature and co2 in both soil levels were monitored sets of tablets were retrieved after 6 and 12 months of the start of the experiment to account for seasonal weathering different lithologies do not exhibit significant differences in weathering although a large inter sample variability is attributed to variable size and distribution of the porosity results show an enhanced weathering during the wet and cold season that accounts for 78 1 of the total annual weathering rock tablets examined under scanning electron microscopy prior and after exposure to natural environment show that most of the material lost occurred along cracks edges or large pores although dissolution is a common process most of the weathering is due to crystal detachment rock tablets at the depth of 5 10 cm were weathered 68 1 more than those set at 50 55 cm from the surface higher soil moisture and concentration of co2 were found deeper in the soil which likely enhanced the dissolution of carbonate however physical weathering dominated weight loss of rock tablets at both soil depths especially at the 5 10 cm level where soil thermal and moisture cycles were more frequent and greater denudation rate calculated from the 12 months set provides values of 2 48 1 07 m yr and 1 75 0 66 m yr at the depths of 5 10 and 50 55 cm respectively since the conditions at the average contact between soil and bedrock are similar to those at the 50 55 cm depth we consider that this is a more reliable denudation rate for the studied location during the studied period the calculated weathering rate suggests that denudation has a limited contribution to the thinning of bedrock over caves at this site therefore we consider that the formation of unroofed caves in this region most likely results from the thinning of bedrock cover over caves due to collapse of blocks from their ceilings

gravitational deformations and fillings of aging caves the example of qesem karst system israel abstract the qesem karst system may serve as an example for aging chamber caves it includes two caves which have undergone several stages of natural and human induced deposition as well as subsidence and collapse natural deposits include calcite speleothems bedrock collapse debris and clay fill karst dissolution and associated sagging and decomposition have operated since the initial cave formation inclined sediments are attributed to several processes mostly dominated by gravitational sagging into underlying dissolution voids affecting cave deposits and sometimes the host rock u th dating shows that speleothem deposition has been common during the mid late quaternary but deposition sites shifted according to local conditions the aging of caves occurs when they become totally filled by sediments and ultimately consumed by surface denudation as documented in qesem cave

fluvial networks of the iberian peninsula a chronological framework abstract knowledge of the evolution of spanish fluvial networks has improved during recent years as more river systems have been studied and more geochronological data has become available however the chronological framework is a major issue as the range of applications is limited by methodological constraints and spatial coverage is sparse integration of absolute dating methods with biostratigraphy and palaeomagnetism permits the recent evolution of these river systems to be reviewed the timing of incision from the late neogene to the present varies between the major iberian fluvial systems depending on the substrata and tectonic settings early pleistocene and older fluvial sequences in the core areas of the iberian peninsula provide a more extensive record of fluvial evolution and are better preserved than the terrace flights in the coastal lowlands middle pleistocene sequences are well developed in most of the major river systems in iberia particularly those of the tajo guadalquivir and aguas river and frequently represent the principal climatic cycles of that period although tectonic and sea level effects can also be seen for late pleistocene to holocene times the scheme becomes more complex our review suggests that each river system has responded differently to local and regional climate control glacial and periglacial processes in headwaters in high mountain areas glacio eustatic sea level changes and local and regional tectonic patterns

importance of suspended sediments and dissolved organic carbon to carbon exports in karst the vadu crisului karst basin in the pădurea craiului mountains romania abstract exports of dissolved inorganic carbon dic from karst aquifers are a significant contribution to the global carbon cycle contributions of particulate inorganic carbon pic and dissolved organic carbon doc in karst groundwater are often unaccounted for in carbon budgets this investigation considers field chemistry discrete samples and continuous monitoring data collected between october 2016 and december 2016 to quantitatively evaluate the net export of dissolved solutes total suspended sediments tss and doc within the vadu crisului karst basin in the p durea craiului mountains of northwest romania measurements of carbon isotopes 13c in dic and in bedrock specific ultraviolet absorption suva and carbon to nitrogen c n ratios were used to evaluate the relative contribution of different sources of carbon to the aqueous system 13cdic at the aquifer input trend toward an atmospheric signal in winter with lower doc concentrations and suva values and c n ratios corresponding to degraded carbon sources illustrating the reduction in microbial respiration in soil with cold temperatures at the spring 13cdic values trend more toward a soil based signal after storm events that bring increased doc concentrations with suva values corresponding to significantly degraded carbon dissolution in this karst basin is principally driven by the carbonate equilibrium reactions and direct meteoric recharge only accounts for 4 to 13 of observed discharge most recharge enters the karst basin through infiltration into dolines and epikarst on the zece hotare karst plateau and this results in a broadly stable chemical signature of spring water storm events do have a significant impact on mechanical erosion and chemical processes operating in the karst basin the addition of pic and tss flux increase landscape erosion rates by 1 1 to 1 2 and 7 9 to 8 3 respectively above the denudation rate computed by dissolved solutes 36 5 56 9 mm ka the modeled annual flux of dic from this karst basin 1 37 105 to 1 64 105 kg yr scales to a global co2 flux of 7 08 1011 to 1 06 1012 kg yr adding a modeled flux of doc increases the estimates of co2 flux by 12 to 22 a significant addition to the global carbon cycle

weathering rates of buried machine polished rock disks karkevagge swedish lapland some 48 dolomite 37 granite and 19 limestone machine polished disks were buried at soil horizon boundaries in 16 soil pits to maximum depths of 0 5 0 6 m within karkevagge a presently periglacial glaciated trough in arctic sweden the objective of the ongoing study is to determine near surface potential weathering rates beneath birch forest dryas heath heath meadow solifluction meadow and willow vegetation cover types selected disks were excavated after 1 year and all disks were excavated after 4 or 5 years the limestone disks weathered fastest followed closely by the dolomite disks but the granite disks weathered at much slower rates mean annual percentage mass loss over 4 or 5 years was 0 473 0 145 two standard errors for dolomite disks 0 032 0 005 two standard errors for granite disks and 1 104 0 446 two standard errors for limestone disks for dolomite disks the dryas heath and heath environments weathered the most slowly a trend that was generally followed by the granite disks poor drainage i e increasing wetness and decreasing ph were found to promote dolomite weathering rates in a statistically significant manner surficial and subsurface weathering rates at individual sites were generally found to be correlated for dolomite but not granite copyright 2002 john wiley sons ltd

morphometric comparison of weathering features on side by side carbonate rock surfaces with different exposure ages a case from the croatian coast this study presents the comparison of morphometry of karren features developed on two rock surfaces located side by side having different exposure times cosmogenic 36cl analyses were used to determine the age of a rock surface exposed after a rockslide that occurred 2400 years ago whereas the rock surface not affected by the slide was exposed to weathering for a longer time period clint and grikes trittkarren rillenkarren solution pits and kamenitzas were measured comparatively less density of grikes on the surface affected by the slide made it having a fresh appearance most of the grikes were inherited from previous weathering stage and exposure time since the rockslide event has not been sufficient to homogenize these features between both rock surfaces tritkarren and rillenkarren were preferentially found on the rockslide surface indicating that their genesis is likely to occur at decadal to centennial timescale solution pits and kamenitzas were found on both surfaces and some of their size parameters were indistinguishable between the populations of both rock surfaces area and depth parameters of both forms were clearly correlated and we define a morphometric index a d ratio as the slope between these two parameters within each population after an initial stage preferential weathering occurs along the vertical axis in solution pits and laterally in kamenitzas thus we suggest that the a d ratio is related to the evolution relative age of the karren features thus under rock surfaces affected by the same weathering conditions lower a d ratios of solution pits and higher a d ratios of kamenitzas indicate longer time exposed to weathering thus although solution pits and kamenitzas are likely to be developed in decadal to centennial timescales their morphology changes through time at millennial timescale and it can be tracked by morphometric analysis