bluuebunny/crossref_metadata_2025 huggingface dataset:
Trace Metal Leachability of Land‐Disposed Dredged Sediments
Authors: Singh Satya P. , Ma Lena Q. , Tack Filip M. G. , Verloo Marc G.
Published: July 2010

The potential risk of surface and ground water contamination by trace metals leached from contaminated land‐disposed dredged sediment is a major environmental concern. The objective of this study was to evaluate trace metal leachability, leachate quality, and environmental effects of land‐disposed dredged sediments (LDDS). In addition to chemical characterization and determination of potential and actual leachability, dredged sediments were also subjected to solid phase fractionation using a sequential extraction procedure. Potential leachability, defined as the maximum metal pool that may become available for leaching at a constant pH 4, decreased in the following order: Zn ∼ Cd > Mn > Ni > Co > Cu ∼ As > Pb > Cr. Potential metal leachability was controlled mainly by solid phase distribution of metals in sediments. The acid‐extractable fraction of most metals correlated well with the potentially leachable metals extracted with a solution of pH 4 (r2 > 0.67), except for Pb. The kinetics of metal release were determined using the cascade leaching test (CLT) with water at pH 4. Except for Ni and Zn in the first fraction, metal concentrations in all consecutive leaching fractions remained below the maximum permissible level in water for human consumption. Actual metal leachability expressed as a percentage of potential leachability varied widely among trace metals and decreased in the order: As > Cu > Cr > Ni > Zn > Cd > Co > Pb. Our results indicate low risk of surface and ground water contamination resulting from land disposal of dredged sediments.
Bioaccumulation of Heavy Metals in Thionic Fluvisols by a Marine Polychaete: The Role of Metal Sulfides
Authors: Otero X. L. , Sánchez J. M. , Macías F.
Published: July 2010

Bioavailable heavy metals have been widely studied in recent years because of their toxicity to natural ecosystems. Despite the number of studies carried out, relatively little is known about the metal fraction that is biologically available. In this study, we analyzed seasonal concentrations of acid‐volatile sulfide (AVS) as well as heavy metals associated with the reactive (soluble in 1 M HCl) and pyrite (soluble in HNO3) fractions of the soils of three salt marshes in the ría of Ortigueira (NW Iberian Peninsula). Heavy metal concentrations in polychaete worms (Nereis diversicolor) collected from each salt marsh were also determined and compared with metal contents in the different fractions of the soil. We did not find a relationship between the concentration of total metal or metal incorporated into the reactive fraction in the soil and the tissue‐metal concentration in N. diversicolor. The results appear to indicate that this species preferentially accumulates metals associated with reduced forms of sulfur (pyrite and presumably AVS). Oxidation of these metal sulfides would lead to release of Cu and Ni into interstitial water and they would then be readily available to be taken up by these organisms, either by absorption through the body surface or across the digestive tract.
Nutrient Concentrations and Discharges in a Midwestern Agricultural Catchment
Authors: Castillo M. M. , Allan J. D. , Brunzell S.
Published: July 2010

The amounts of nitrogen and phosphorus in river water are significantly influenced by anthropogenic inputs associated with land cover, land use, and point sources. We quantified seasonal and spatial patterns in the concentrations of nitrate N and soluble reactive phosphorus (SRP) at 17 sites distributed among tributaries and along the mainstem of the River Raisin, Southeastern Michigan, and also determined land cover, surficial geology, and discharges from waste water treatment plants (WWTPs). Annual flow‐weighted mean concentrations (FWMCs) ranged from nondetectable levels to 18.1 mg L−1 for nitrate and to 184 µg L−1 for SRP. Nitrate concentrations increased from headwaters to river mouth, and were highest in spring and in association with high runoff episodes. Mean nitrate concentration correlated strongly with the ratio of agricultural to forested land upstream of the sampling location. Concentrations of SRP also increased markedly from headwaters downstream, and exhibited little seasonal variation other than a modest increase during the summer period of low flow. Geology and phosphorus loading from WWTPs best predicted SRP concentrations. The annual yield of nitrate was consistent with expectations based on land use. Point source loading contributed a negligible fraction of the river's discharge of nitrate and at most one‐fourth of its SRP discharge. Compared with findings from headwater sites and other, less altered rivers, nutrient concentrations in this catchment appear strongly influenced by human activity.
Soil Phosphorus Fertility Degradation: A Geographic Information System‐Based Assessment
Authors: Brown S. , Schreier H. , Shah P. B.
Published: July 2010

Soil phosphorus is a critical macronutrient limiting agricultural productivity in many parts of Nepal. This study evaluates a geographic information system (GIS)‐based approach to assess soil P degradation risk as influenced by site factors and human land use impacts. The status of P fertility in a Nepalese watershed was evaluated by stratifying the soil analysis by soil type, elevation, aspect, and land use (irrigated or rainfed agriculture, rangeland, and forests). Human impacts were shown to be significant, and with GIS overlay techniques it was possible to produce a soil P status map based on land use and soil type. Some 27% of the area was found to be deficient in P. Soil nutrient budgets displaying annual surplus or deficit conditions for the common crops were combined with the soil fertility map to derive a soil P degradation risk map. Low P conditions with high annual deficits posed the greatest degradation risk, while adequate P status with high annual deficits were of more long‐term concern. Forty‐eight percent of the area was considered at low risk because of adequate conditions and minimal deficits for P. In contrast, some 36% of the study area had a high short‐term risk for degradation because of the low status and high annual deficit in P. Given the dynamics of soil fertility, the site factor approach used in combination with soil analysis, nutrient budget calculations based on farm interview data, and GIS overlay techniques provided a unique way of assessing long‐term soil P degradation risks.
Factors Affecting Phosphorus Export from a Pasture‐Based Grazing System
Authors: Nash David , Hannah Murray , Halliwell David , Murdoch Craig
Published: July 2010

Pasture‐based grazing systems contribute to the excessive nutrients found in some streams in southern Australia. This study investigated P exported from a 3.6 ha dairy pasture receiving high levels of P fertilizer with a view to identifying factors affecting P export. The runoff from 34 storms was monitored to examine factors thought to be associated with the variation in total phosphorus (TP). The relationships between TP and days since grazing (DG), days since fertilizing (DF), total storm flow (TF), and season (year and time of year) were examined. The variable DF was inversely related to the flow‐weighted mean TP concentration (P < 0.001) and accounted for 50.6% (adjusted R2) of the variance in ln (TP). However, DG was only weakly correlated to TP, suggesting that cattle did not mobilize large stores of available P relative to the fertilization at the study site. The initial half‐life of fertilizer effect (i.e. the period of time since fertilizing in which the TP concentration decreased by half) was estimated to be 4.3 d, with a 95% confidence interval of 3.1 to 8.0 d. However, unlike exponential decay where the half‐life is constant, the decay rate for these data declined over time. The data adjusted for the effects of DG and TF show little evidence of decline in TP after 20 d since fertilizing. Management of fertilizer application in relation to the timing of runoff events appears the main method by which P export can be decreased in the type of pasture‐based grazing system studied here.
Relating Soil Phosphorus Indices to Potential Phosphorus Release to Water
Authors: Hooda P. S. , Rendell A. R. , Edwards A. C. , Withers P. J. A. , Aitken M. N. , Truesdale V. W.
Published: July 2010

Relationships between soil test phosphorus (STP) and release of P in surface and subsurface runoff are needed to help identify source areas for implementing management strategies to limit P loss to water. To determine whether soil P release could be predicted either by STP values, sorption‐desorption indices, or the degree of soil saturation with phosphorus (DSSP), 11 sites with contrasting chemical properties and management histories were sampled from long‐term field trials in the UK. Each site offered up to three treatments, resulting in a total of 29 soil samples. The results showed that the amount of P desorbed using a successive dilution procedure had no relationship with either total soil P content or P sorption capacity. The most significant property was the extent of P saturation. There was little desorption for DSSP values below 10%; above this point, the amount of P desorbed increased linearly with the DSSP. Five STP methods (Olsen, Mehlich‐3, acidified ammonium oxalate‐oxalic acid, Fe2O3‐coated paper strip, and distilled water) were compared to predict their effectiveness in predicting potential P release to water. While STP values obtained using acidified ammonium oxalate proved to be least effective, those extracted with water correlated best with the amount of P desorbed, accounting for 96% of the variability in differential P release from the soils.
Respective Horizon Contributions to Cesium‐137 Soil‐to‐Plant Transfer: A Pot Experiment Approach
Authors: Thiry Yves , Kruyts Nathalie , Delvaux Bruno
Published: July 2010

The OAh horizons in forest acid soils are reported to fix more radiocesium than the mineral horizons beneath and organic horizons above them. We determined the respective contributions of the Of, OAh, Ah, and Bw horizons in an acid brown soil to the total 137Cs soil‐to‐plant transfer by using young spruce plants [Picea abies (L.) H. Karst.l grown on reconstituted micro‐pedons in which these respective horizons were contaminated by carrier‐free 137Cs. The plants were grown in a greenhouse at 20°C during a period of 5 mo. The respective contributions to the 137Cs soil‐to‐plant transfer were 92.71% in Of, 0.18% in OAh, 3.28% in Ah, and 3.83% in Bw. The very high contribution of Of was due to its high organic matter (OM) content, while the very low contribution of OAh was related to Cs+ fixation by vermiculitic clay minerals. The higher 137Cs transfer from Ah and Bw vs. OAh was probably associated with Al interlayering of vermiculite. Our data suggest that plant roots and soil vermiculite acted as competitive sinks for 137Cs in the acid brown soil.
Multispecies Riparian Buffers Trap Sediment and Nutrients during Rainfall Simulations
Authors: Lee Kye‐Han , Isenhart Thomas M. , Schultz Richard C. , Mickelson Steven K.
Published: July 2010

A study was conducted to evaluate the ability of a multispecies riparian buffer (MRB) to remove sediment, nitrogen, and phosphorus from cropland runoff. Simulated rainfall was applied to 4.1‐ by 22.1‐m bare cropland source areas paired with either no buffer, a 7.1‐m‐wide switchgrass (Panicum virgatum L. cv. Cave‐n‐Rock) buffer, or a 16.3‐m‐wide switchgrass‐woody plant buffer. Each treatment plot combination had three replicates. The switchgrass buffer trapped 70% of the incoming sediment, while the switchgrass‐woody buffer trapped more than 92%. In general, these buffers retained 93% of sand and silt particles and 52% of clay particles. During a 2‐h rainfall simulation at 25 mm h−1, the switchgrass buffer removed 64, 61, 72, and 44% of the incoming total N, NO3−N, total P, and PO4‐P, respectively. The switchgrass‐woody buffer removed 80, 92, 93, and 85% of the incoming total N, NO3−N, total P, and PO4‐P, respectively. During a 1‐h rainfall simulation at 69 mm h−1, the switchgrass buffer removed 50, 41, 46, and 28% of the incoming total N, NO3−N, total P, and PO4‐P, respectively. The switchgrass‐woody plant buffer removed 73, 68, 81, and 35% of the incoming total N, NO3−N, total P, and PO4‐P, respectively. The switchgrass buffer was effective in trapping coarse sediment and sediment‐bound nutrients. But the additional buffer width with high infiltration capacity provided by the deep‐rooted woody plant zone was effective in trapping the clay and soluble nutrients.
The Influence of Vegetation in Riparian Filterstrips on Coliform Bacteria: II. Survival in Soils
Authors: Entry James A. , Hubbard Robert K. , Thies Janice E. , Fuhrmann Jeffry J.
Published: July 2010

Survival of total and fecal coliform bacteria was measured in the 0 to 5, 5 to 15, and 15 to 30 cm soil depths at 1, 3, 7, 14, and 90 to 120 d after swine (Sus scrofa) wastewater application to riparian filterstrips in southern Georgia during each season of the year. Vegetative treatments evaluated were: (i) 20 m grass‐10 m forest, (ii) 10 m grass‐20 m forest, and (iii) 10 m grass‐20 m maidencane (Panicum hemitomon Schult.). During winter, spring, and summer vegetation type in riparian filterstrips did not affect survival of total and fecal coliform bacteria. Total and fecal coliform bacterial numbers were usually higher in the top 0 to 5 cm of soil than in the 5 to 15 and 15 to 30 cm soil depths in all treatments. Total and fecal coliform numbers in the 0 to 5, 5 to 15, and 15 to 30 cm depths declined approximately 10‐fold every 7 to 14 d after waste application in all seasons of the year. At 90 to 120 d after waste application, total and fecal coliform numbers in the three soil depths did not differ from riparian filterstrips that did not have animal waste applied. Total coliform bacteria in the 0 to 5, 5 to 15, and 15 to 30 cm soil depths correlated with temperature and moisture in a curvilinear relationship (r2 = 0.80, 0.77, and 0.64, respectively). Fecal coliform bacteria in 0 to 5, 6 to 15, and 16 to 30 cm of soil also correlated with temperature and moisture in a curvilinear relationship (r2 = 0.56, 0.53, and 0.53, respectively).
Effectiveness of Coal Combustion By‐Products in Controlling Phosphorus Export from Soils
Authors: Stout William L. , Sharpley Andrew N. , Landa Jennifer
Published: July 2010

Phosphorus (P) export from high P soils is a major cause of eutrophication in fresh waters. Recent work has shown that the solubility of P in high P soils can be reduced with coal combustion by‐products (CCBs), decreasing the potential for dissolved phosphorus (DP) export from these soils. However, the effect of such treatments on plant‐available P and P export has not been quantified. We measured P uptake by canola (Brassica napus L.) from three high P (130–370 mg kg−1 Mehlich‐3 P) soils treated with two CCBs, fluidized bed combustion flyash (FBC), flue gas desulfurization (FGD) CaSO4 anhydride, and agricultural gypsum (GYP). We measured DP, particulate phosphorus (PP), and total phosphorus (TP) concentrations in runoff from grassed and bare soils treated with these materials and subjected to simulated runoff. Phosphorus, As, Cd, and Pb uptake by canola were unaffected by CCB treatment, and dry‐matter yields were unrelated to treatment. On grassed soils, FBC, FGD, and GYP reduced DP concentration in runoff by 20, 43, and 33%, respectively, but did not affect As, Cd, or Pb concentrations in runoff. Also on grassed soils, the high application rate of FGD reduced TP in runoff by 35%. On bare soils where erosion of PP controlled P loss, CCBs and GYP had no effect on DP concentration in runoff. Application of CCBs to high P soils in zones of high surface runoff potential, where there is little erosion, has the potential to reduce P export without affecting crop production.
Effectiveness of Constructed Wetlands in Reducing Nitrogen and Phosphorus Export from Agricultural Tile Drainage
Authors: Kovacic David A. , David Mark B. , Gentry Lowell E. , Starks Karen M. , Cooke Richard A.
Published: July 2010

Much of the nonpoint N and P entering surface waters of the Midwest is from agriculture. We determined if constructed wetlands could be used to reduce nonpoint N and P exports from agricultural tile drainage systems to surface waters. Three treatment wetlands (0.3 to 0.8 ha in surface area, 1200 to 5400 m3 in volume) that intercepted subsurface tile drainage water were constructed in 1994 on Colo soils (fine‐silty, mixed, superactive, mesic Cumulic Endoaquoll) between upland maize (Zea mays L.) and soybean [Glycine max (L.) Merr.] cropland and the adjacent Embarras River. Water (tile flow, precipitation, evapotranspiration, outlet flow, and seepage) and nutrient (N and P) budgets were determined from 1 Oct. 1994 through 30 Sept. 1997 for each wetland. Wetlands received 4639 kg total N during the 3‐yr period (96% as NO3‐N) and removed 1697 kg N, or 37% of inputs. Wetlands decreased NO3−N concentrations in inlet water (annual outlet volume weighted average concentrations of 4.6 to 14.5 mg N L−1) by 28% compared with the outlets. When the wetlands were coupled with the 15.3‐m buffer strip between the wetlands and the river, an additional 9% of the tile NO3−N was apparently removed, increasing the N removal efficiency to 46%. Overall, total P removal was only 2% during the 3‐yr period, with highly variable results in each wetland and year. Treatment wetlands can be an effective tool in reducing agricultural N loading to surface water and for attaining drinking water standards in the Midwest.
Phosphorus Movement Through a Coastal Plain Soil After a Decade of Intensive Swine Manure Application
Authors: Novak J. M. , Watts D. W. , Hunt P. G. , Stone K. C.
Published: July 2010

Understanding the movement of phosphorus (P) in soils receiving heavy animal waste application is important for nonpoint‐source pollution control. We investigated both P accumulation in soil and movement to ground water after 10 yr of intensive swine manure application (at atypical high rates) to a Coastal Plain spray field. Mehlich 3 phosphorus (M3P) was measured in soil cores collected in 1991 (following 4 yr of manure application) and 1997 (after 10 yr of application). Additionally, dissolved phosphorus (DP) was measured in ground water wells installed around the spray field. In both 1991 and 1997, the soil cores (0 to 15 cm) contained high contents of M3P (376–435 mg P kg−1) indicating substantial P accumulation. After 10 yr of manure application, soil cores at a depth of 107 cm were also high in soil M3P contents (151 mg P kg−1). Control soils were very low in M3P (<10 mg P kg−1) throughout the soil profile. Ground water DP concentrations were initially (1992–1995) very low (<40 µg P L−1), but by late 1996, DP concentrations in a few wells had increased substantially (40–480 µg P L−1). In contrast, ground water control wells (1994–1998) were very low in DP (<40 µg P L−1). Thus, the studied field, which received atypical high loading rates, had detectable leaching to shallow ground water as well as substantial P accumulation.
Nitrogen Fertilizer Equivalency of Sewage Biosolids Applied to Dryland Winter Wheat
Authors: Barbarick K. A. , Ippolito J. A.
Published: July 2010

Determining the N fertilizer equivalency or mineralization rates associated with continuous application of biosolids are paramount in estimating “agronomic rates” for various crops. We used 6 yr of field‐study data from sewage biosolids application to dryland hard‐red winter wheat (Triticum aestivum L., ‘TAM107’) to estimate the N fertilizer equivalency and mineralization rates of Littleton and Englewood (L/E) biosolids. We made three L/E biosolids and urea applications to two sites (Weld loam soil) using a dryland winter wheat summer‐fallow management system. Biosolids rates were 0, 2.2, 4.4, 6.6, 8.8, and 11 dry Mg ha−1 while N fertilizer rates were 22, 44, 66, 88, and 110 kg N ha−1; we replicated all treatments four times. Using N uptake data, we found application of 1 dry Mg of L/E biosolids before each planting delivered an equivalent of about 8.2 kg N fertilizer. By contrast, estimates ranged from 6.2 to 6.7 kg fertilizer N Mg−1 L/E biosolids using the USEPA plant‐available N calculations. We also calculated, from our field‐study results and USEPA estimations, first‐year mineralization rate ranges of 25 to 32%. In a companion greenhouse study, we found that a single application of biosolids provided an N response for only two wheat croppings. These approximations should help managers determine the “agronomic rate” for continuous biosolids additions to dryland winter wheat.
Depth Variation in Copper, Lead, and Zinc Concentrations and Mass Enrichment Ratios in Soils of an Urban Watershed
Authors: Sutherland R. A.
Published: July 2010

Previous studies in the Manoa watershed (Hawaii) have indicated significant anthropogenic enhancement of trace metals in road deposited sediment and fluvial bed sediments. This study was conducted to examine trace metal loadings with depth in soils of Manoa watershed. A total of 78 roadside (disturbed) and 10 background (control) soils were sampled at two depths for selected soil properties and for total and HCl‐extractable (labile) concentrations of Al, Cu, Pb, and Zn. Based on sample proximity to roads, typically <2 m, the automobile is considered the primary source of inputs. Concentration, mass loading, and mass per area enrichment ratio (MAER) data indicate that Pb was the most significantly enhanced trace metal. Labile Pb concentrations were log‐normally distributed with maximum values of 2870 and 3560 mg kg−1 in topsoil and subsoil samples, respectively. Roadside labile Pb was four to five times higher than in background soils. Mass loading and MAER data indicate that subsoils were statistically more enriched in labile Cu and Pb, while Zn had similar values with depth. More than 50% of the subsoils were classified as having significant to extreme labile Pb anthropogenic signals. Trace metals in this study have undergone significant translocation, possibly through processes of colloidal transport and/or preferential flow. The environmental significance of this research is discussed in terms of potential influence of Pb mobility on ground and surface waters, and the continued contribution of high levels of labile Pb to road surfaces with erosion of exposed subsoil layers.
A Time‐Dependent Model of Nitrogen Loading to Estuaries from Coastal Watersheds
Authors: Brawley John W. , Collins Glynnis , Kremer James N. , Sham Chi‐Ho , Valiela Ivan
Published: July 2010

We have developed a dynamic nitrogen loading model (NLM) that incorporates temporal and spatial trends in land use with a three‐dimensional ground water model. In conjunction with historical patterns of land use in the Waquoit Bay (USA) watershed, we have modified an existing steady‐state watershed NLM to estimate historical and future rates of total dissolved nitrogen (TDN) to the coastal margins of Waquoit Bay and its subestuaries. The model simulations indicated a significant increase in nitrogen loading to these systems in recent decades. We estimated that the TDN loading rate to Waquoit Bay increased from approximately 5000 to 23 000 kg yr−1 (0.8 to 3.7 g N m−2 yr−1) from 1930 to 1990. We also compared the dynamic model with steady‐state simulations where the lag effect of ground water travel time was not considered. These results indicate occasional significant differences (up to 37%) between the two modeling methods, especially between 1950 and 1990, when large areas of naturally vegetated and agricultural land within the watershed were converted to unsewered residential housing. Although all subestuaries experienced similar temporal trends in nitrogen load, heterogeneity in the timing, source, and magnitude indicates that these factors are dependent upon watershed size, shape, and spatio‐temporal trends in land use.
Transformation of 1,3‐Dichloropropene in Soil by Thiosulfate Fertilizers
Authors: Gan J. , Yates S. R. , Knuteson J. A. , Becker J. O.
Published: July 2010

The pesticide 1,3‐dichloropropene (1,3‐D) is considered to be the most promising alternative to methyl bromide for soilborne pest control. The high volatility of 1,3‐D, however, has been shown to result in excessive atmospheric emissions that may impose toxicological effects on workers or residents. This study demonstrated that 1,3‐D was rapidly transformed to nonvolatile products by thiosulfate fertilizers in soil, and that thiosulfate‐facilitated fumigant transformation may be used to reduce 1,3‐D emissions. Transformation of 1,3‐D by thiosulfate was chemically based, and 1,3‐D degradation in soil accelerated proportionally as thiosulfate level in soil increased. At a 4:1 thiosulfate to fumigant molar ratio, the half‐life of 1,3‐D was reduced to only a few hours, as compared with >10 d for nonamended soils. The rate of thiosulfate‐facilitated 1,3‐D transformation was independent of soil types and was higher in moist soils and at high soil temperatures. Transformation occurred at a similar rate for ammonium, calcium, and sodium thiosulfates. As these thiosulfate compounds are commercial fertilizers, amendment of these products at the soil surface during 1,3‐D fumigation may offer an effective and inexpensive approach for reducing 1,3‐D emissions.
Kinetics of Carbosulfan Degradation in the Aqueous Phase in the Presence of a Cosolvent
Authors: Wei Jiang , Furrer Gerhard , Schulin Rainer
Published: July 2010

The degradation of the carbamate pesticide carbosulfan (2,3‐dihydro‐2,2‐dimethyl‐7‐ben/ofuranyl [(dibutylamino)thio]methylcarbamate] was investigated in aqueous buffer solutions (pH 3.0–7.0) containing low (1%, v/v) and high (10–60%, v/v) concentrations of acetonitrile. The cleavage of the carbamyl N‐S bond yields carbofuran (2,3‐dihydro‐2,2‐dinicthyl‐7‐benzofuranol methylcarbamate). The rate of carbosulfan degradation depends on pH, the initial concentration of carbosulfan, acetonitrile concentration, shaking speed, ionic strength, and temperature. Carbosulfan was completely dissolved only in solutions with high acetonitrile concentrations. The concentration of acetonitrile needed for the complete dissolution of carbosulfan depended on the initial concentration of carbosulfan. In this case, the degradation is a pseudo‐second‐order reaction with respect to the concentration of carbosulfan and hydronium ion. The degradation reaction is promoted by the hydronium ion. In the case of low acetonitrile concentrations, where carbosulfan was not completely dissolved, the overall kinetics depend also on the slow dissolution process. The degradation of carbosulfan probably is not a pure hydrolysis reaction, but a protonation‐intermolecular rearrangement reaction. The results indicate that the abiotic degradation of carbosulfan in natural waters is a very slow process when organic solvents and minerals are absent or present in only minor concentrations.
Effect of Soil Texture on Nitrogen Mineralized from Cotton Residues and Compost
Authors: Egelkraut T. M. , Kissel D. E. , Cabrera M. L.
Published: July 2010

The N mineralized from microbial decomposition of crop residues is an important source of N for crop production. Our objective was to develop a better understanding of how soil properties affect the N mineralized from decomposing crop residues to help better account for spatial differences in N availability when applying N fertilizer. Four soils varying in texture and organic matter concentration were selected from a Georgia Coastal Plain field. In the laboratory, the soils were mixed with cotton (Gossypium hirsutum L.) leaves (C to N ratio = 15.5), cotton stems (C to N ratio = 28.8), or compost (C to N ratio = 28.8) and incubated at field capacity and 23°C for 179 d. Rates of application were 2056 mg plant material kg−1 soil and 15 000 mg compost kg−1 soil. The time spans of initial N immobilization and the amounts of N immobilized and mineralized differed considerably between soils. The soils with greater clay concentrations had longer time periods of initial N immobilization and mineralized less N from the added materials. The net N mineralized from the decomposing cotton residues was low after 179 d in all four soils (−2.6 to 11.0% of total), but greater amounts of N were mineralized from decomposition of compost (5.1 to 23.1% of total).
Statistical Evaluation of Effects of Riparian Buffers on Nitrate and Ground Water Quality
Authors: Spruill Timothy B.
Published: July 2010

A study was conducted to statistically evaluate the effectiveness of riparian buffers for decreasing nitrate concentrations in ground water and for affecting other chemical constituents. Values for pH, specific conductance, alkalinity, dissolved organic carbon (DOC), silica, ammonium, phosphorus, iron, and manganese at 28 sites in the Contentnea Creek Basin were significantly higher (p < 0.10) in old (>20 yr) discharging ground water draining areas with riparian buffers compared with areas without riparian buffers. No differences in chloride, nitrate nitrogen, calcium, sodium, and dissolved oxygen concentrations in old ground water between buffer and nonbuffer areas were detected. Comparison of samples of young (<20 yr) discharging ground water samples from buffer and nonbuffer areas indicated significantly higher specific conductance, calcium, chloride, and nitrate nitrogen in nonbuffer areas. Riparian buffers along streams can affect the composition of the hyporheic zone by providing a source of organic carbon to the streambed, which creates reducing geochemical conditions that consequently can affect the chemical quality of old ground water discharging through it. Buffer zones between agricultural fields and streams facilitate dilution of conservative chemical constituents in young ground water that originate from fertilizer applications and also allow denitrification in ground water by providing an adequate source of organic carbon generated by vegetation in the buffer zone. Based on the median chloride and nitrate values for young ground water in the Contentnea Creek Basin, nitrate was 95% lower in buffer areas compared with nonbuffer areas, with a 30 to 35% reduction estimated to be due to dilution and 65 to 70% due to reduction and/or denitrification.
Curve Number Approach for Estimating Runoff from Turf
Authors: Haith Douglas A. , Andre Benjamin
Published: July 2010

The curve number equation is one of the simplest and most commonly used models for estimating surface runoff. However, its applicability to turfgrasses has not been previously demonstrated. This study evaluated the approach by comparing model estimates with measured runoff data from turf field plots in six different states, including three different soil hydrologic groups, four turfgrasses, and a range of antecedent moisture and turf conditions. A set of curve numbers were developed for short and long grasses with and without thatch, and curve number selection was based on linear functions of 5‐d antecedent precipitation. With the standard growing season antecedent moisture limits of 36 mm and 53 nun, the curve number model explained 78% of the observed variation in runoff and underpredicted the mean event runoff by 15%. With a downward adjustment of these limits to 22 nun and 53 mm in split‐sample calibration, the underprediction of means was reduced to less than 3%. More significantly, the model mean for the largest observed events was within 6% of the observed mean. Provided model results are interpreted in a statistical sense rather than as individual events, the curve number model, as modified in this study, is a relatively accurate means of estimating turf runoff.
Isotopic Evidence for Naturally Occurring Sulfate Pollution of Ponds in the Kankakee River Basin, Illinois‐Indiana
Authors: Sidle W. C. , Roose D. L. , Shanklin D. R.
Published: July 2010

Ecosystem restoration surveys across the Kankakee River Basin indicate that ponds in riparian zones contain elevated sulfate concentrations. The sources of high sulfate in many ponds were investigated by sampling ground waters, precipitation, and applied fertilizers in the Kankakee and Iroquois subwatersheds of the basin. The 34SSO4 and 18SSO4 analyses discriminated among possible regional anthropogenic and natural sources. Some sulfate‐bearing fertilizers may have contributed to elevated SO2−4 in ponds but there is isotopic evidence suggesting that pyritic glaciofluvial sediments in the surficial aquifer may be the source of larger SO2−4 concentrations in ponds. An isotopic analysis of one SO2−4−H2O system in a riparian zone revealed that FeS2 oxidation reactions are possible processes leading to local sulfate pollution in riverine ponds.
17β‐Estradiol and Testosterone in Soil and Runoff from Grasslands Amended with Broiler Litter
Authors: Finlay‐Moore O. , Hartel P. G. , Cabrera M. L.
Published: July 2010

In 1998, the U.S. poultry industry generated almost 12 million Mg of broiler (Gallus gallus domesticus) litter, most of which was applied to grasslands as fertilizer. This litter contains appreciable concentrations of estradiol and testosterone, sex hormones of environmental concern. We measured estradiol and testosterone concentrations in soil and runoff water from large (0.8 ha) grazed and ungrazed grasslands amended with broiler litter. Samples were analyzed by enzyme immunoassay. In runoff, background concentrations were 50 to 150 ng estradiol L−1 and 15 to 125 ng testosterone L−1. No significant differences were observed in runoff concentrations between hayed and grazed plots (p = 0.1). Therefore, grazing animals did not contribute hormones to runoff. When litter was applied, runoff concentrations were 20 to 2530 ng estradiol L−1 and 10 to 1830 ng testosterone L−1, depending on litter application rate and time between application and runoff. In soil, the background concentration for estradiol was 55 ng kg−1. Depending on litter application rate and time from application, the estradiol concentration in soil increased up to 675 ng kg−1. Testosterone followed a similar trend; however, concentrations of testosterone were significantly higher in grazed than in hayed plots (p = 0.1). These results show sizable edge‐of‐field losses of estradiol and testosterone from broiler litter‐amended grasslands, and are the first studies to measure estradiol and testosterone in soil. Future research needs to examine the persistence and degradation of estradiol and testosterone in broiler litter, soil, and runoff.
Atrazine Adsorption and Colloid‐Facilitated Transport through the Unsaturated Zone
Authors: Sprague Lori A. , Herman Janet S. , Hornberger George M. , Mills Aaron L.
Published: July 2010

One explanation for unexpectedly widespread ground water contamination from atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine) may be the occurrence of colloid‐facilitated transport, whereby the dissolved herbicide becomes adsorbed to mobile colloids that migrate through preferential flow‐paths in the soil zone and into the ground water. The objectives of this study were to determine the extent of adsorption of atrazine to bulk soil and to soil colloids and to determine the extent of colloid‐facilitated transport of atrazine at a field site in Virginia during simulated rainfall events. Equilibrium batch adsorption experiments were performed over a concentration range of 0.05 to 10.0 mg atrazine L−1 on bulk soil samples and on colloidal suspensions of 75 mg L−1, a concentration comparable with those observed at the field site. Linear partition coefficients ranged from 0.496 to 2.48 L kg−1 for the bulk soil and from 70.8 to 832 L kg−1 for the soil colloids. In the field, gravity lysimeters were installed at a depth of 25 cm below the surface of six 0.25‐m2 undisturbed plots. Mass recovery of surface‐applied atrazine in the lysimeters was not significantly affected by rainfall rate and was, on average, 2.7% for plots receiving 25 mm h−1 simulated rainfall and 3.6% for plots receiving 50 mm h−1 simulated rainfall. Of the total atrazine collected in the lysimeters, the fraction that was colloid‐associated ranged from 4.9 to 30% (mean of 15%), indicating that a measurable portion of mobile atrazine is transported via association with colloids.
Wood Ash Control of Odor from Biosolids Application
Authors: Rosenfeld Paul E. , Henry Charles L.
Published: July 2010

Odor emissions from land application of biosolids have become a concern for biosolids managers. Chemical odorant emissions from biosolids were identified using gas chromatography‐mass spectrometry and included dimethyl disulfide (DMDS), dimethyl sulfide (DMS), carbon disulfide (CS2), ammonia (NH3), trimethyl amine (TMA), and acetone. Odor unit measurements (odor intensity as perceived by people) were then related to chemical odorant concentrations. Odor unit emissions were positively correlated with DMDS emissions. To control biosolids odor, wood ash containing 87, 32, 27, 5.4, and 0.24% carbon was incorporated with biosolids (1:1 dry weight ratio). The wood ash possessed surface areas of 520, 85, 74, 25, and 2.1 m2 g−1, respectively. Ash additions reduced odor unit and emissions of DMDS, DMS, and CS2 when compared with the biosolids control, depending upon ash C content and surface area. Although ash additions reduced emissions of acetone, TMA, and sometimes NH3, reduction was not consistently significant. Using the SCREEN3 dispersion model (USEPA, 1995a), maximum DMDS and NH3 concentrations at a 21 Mg ha−1 biosolids application (dry weight) were estimated to be 8.9 and 6.8 times above published human detection limits, respectively, while maximum CS2, DMS, acetone, and TMA concentrations were predicted to be 0.013, 0.017, 0.026, and 0.45 times below published human detection limits, respectively. Incorporation of high carbon wood ash with biosolids eliminated DMDS odor, while wood ash did not significantly reduce the NH3 odor.
Nitrogen and Carbon Mineralization of Potential Manure Components
Authors: Van Kessel J. S. , Reeves J. B. , Meisinger J. J.
Published: July 2010

Current estimates of plant availability of manure N are highly variable. A study was conducted to examine C and N mineralization characteristics of manure components from feeds (immature and mature alfalfa and orchardgrass, soybean meal, roasted soybean meal), forage cell walls (acid detergent fiber [ADF] and neutral detergent fiber [NDFI), simple N compounds (urea, amino acids and peptides), and nondietary metabolic components (ruminal bacteria and colonic cells). Nitrogen and C mineralization were determined by aerobic incubation of sample‐amended soil. Changes in NH+4 and NO−3 concentration and CO2 production were monitored over 112 d. At C to N ratios below 15, there was a declining exponential relationship between the initial potential rate of C mineralization and the sample C to N ratio. However, at C to N ratios above 15, the initial potential rate of C mineralization was low and insensitive to C to N ratio. Percent of added N mineralized ranged from 92% for urea and 13% for mature orchardgrass to a net N immobilization for ADF‐ and NDF‐amended soils. When the C to N ratio was below 42, there was a linear relationship between readily mineralizable N and the C to N ratio. There were also positive relationships between readily mineralizable C and N and the components' total N concentration. Manure contains a range of compounds that have rapid or intermediate N mineralization characteristics, or that are strong immobilizers of N. These results suggest that improved estimates of manure N mineralization may be obtained by considering both the readily available N components and components that strongly immobilize N.
Fate and Behavior of Lead in Soils Planted with Metal‐Resistant Species (River Birch and Smallwing Sedge)
Authors: Klassen Steve P. , McLean Joan E. , Grossl Paul R. , Sims Ronald C.
Published: July 2010

Phytoremediation of metal‐contaminated soils requires an understanding of the interactions between metal‐tolerant plant species and soil chemical properties controlling the bioavailability of metals. We conducted controlled laboratory studies to investigate the effects that river birch (Betula occidentalis Hook.) and smallwing sedge (Carex microptera Mack.) had on the fate and behavior of Pb in a contaminated soil (3000 mg Pb/kg) and tailings (13 000 mg Pb/kg) collected from an abandoned mining site in Utah. Significant Pb accumulation in aboveground tissue was observed in smallwing sedge (≥1000 mg/kg dry wt.) in both the soil and tailings, but Pb was primarily excluded by birch (≤300 mg/kg dry wt.). Lead exclusion in birch resulted in elevated concentrations of Pb in the rooting zone in both the soil and tailings. In the soil, the exchangeable Pb concentration of the unplanted control was not significantly different than the birch rhizosphere but was higher than the birch bulk (nonrhizosphere) soil fraction. This suggested that plants using exclusionary mechanisms of metal resistance may promote soil Pb stabilization by sequestering normally mobile fractions of Pb in the rhizosphere. However, both birch and smailwing sedge increased the leachate Pb concentration by 2 mg/L and decreased the pH by one unit in the tailings compared with unplanted controls. Leachate Pb concentrations and pH were not significantly affected by plants in the soil. This indicated that the ability of metal‐resistant plants to promote soil Pb stabilization is soil specific and depends on the level of Pb contamination and soil characteristics controlling the solubility and mobility of Pb.
Direct Quantification of Metal‐Organic Interactions by Size‐Exclusion Chromatography (SEC) and Inductively Coupled Plasma Mass Spectrometry (ICP‐MS)
Authors: Piatina Tatiana B. , Hering Janet G.
Published: July 2010

Metal speciation significantly influences the geochemical cycling of trace metals and can control metal bioavailability and toxicity. Advanced analytical techniques have been applied to address some difficulties encountered in identifying metal organic species. In this method, size‐exclusion chromatography (SEC) was directly coupled with inductively coupled plasma mass spectrometry (ICP‐MS) to determine conditional stability constants of metal complexes with strong organic ligands in competitive equilibration experiments. Molecular size calibration of the column was performed with polystyrenesulfonate standards and the effects of hydrophobic interactions on the column were determined. Metal concentrations corresponding to different organic fractions were measured directly, in the SEC column effluent, by ICP‐MS. The method was validated with well‐defined organic ligands in ligand competition studies with a single metal and a binary metal mixture. The distribution of metal‐ligand species determined analytically was shown to correspond to the calculated equilibrium speciation. Model studies using metal complexes with weaker organic ligands demonstrated that the technique is subject to kinetic limitations since labile metal‐organic complexes can dissociate during chromatographic separation. Nonetheless, the kinetic window of the method should be appropriate for the strong ligands postulated to control metal speciation in natural waters.
Microbial Decomposition of Dissolved Organic Matter and Its Control during a Sorption Experiment
Authors: Zhou L. X. , Wong J. W. C.
Published: July 2010

This paper describes a detailed investigation on the effect of microbial activity on apparent dissolved organic matter (DOM) sorption in batch experiments and means to control it. The adsorption and decomposition dynamics of DOM derived from three organic wastes (green manure, pig manure, and sewage sludge) were performed at 4 or 22°C in the presence and absence of 5 mM NaN3. No DOM decomposition occurred in sorption experiments performed at 4 or 22°C receiving NaN3, while significant reduction was noted at 22°C without NaN3 addition after 24 h shaking. The sequence of DOM susceptibility to microbial decomposition in a 24‐h period was: green manure > pig manure > sewage sludge. A shaking period of 2 h was found too short for notable microbial activity as compared with that of 24 h shaking but long enough to achieve equilibrium adsorption at 22°C. Therefore, sorption experiments performed at ambient temperatures with a long equilibrium period will overestimate the amount of DOM adsorbed and lead to an incorrect interpretation of the DOM adsorption behavior because of the involvement of microbial decay of DOM. It is recommended that batch equilibrium DOM adsorption studies be performed at either 4°C for 24 h or at ambient temperatures for 2 h, while addition of 2.5 to 5 mM of NaN3 is also a possible alternative for an equilibrium period of >2 h.
Phosphorus Accumulation in Farm Ponds and Dams in Southwestern Australia
Authors: Ruan Huada D. , Gilkes Robert J.
Published: July 2010

Eutrophication of farm ponds and dams (earth tanks) due to elevated dissolved phosphorus concentrations causes death of fish, crustaceans, and animals. Phosphorus accumulation in water and sediment in 50 farm ponds and dams and 2 streams was investigated for a 4000‐ha area near York, Western Australia. Water, sediment, and soil samples were analyzed for total, inorganic, and organic P. Sediments contained between 4 and 54% clay. The major minerals in the clay fraction were quartz, kaolinite, and smectite with minor amounts of illite, felspars, calcite, and iron oxides. Sediments contained between 0.4 and 5.9 g kg−1 N, 6.0 and 14.3 g kg−1 AI, 15.0 and 77.0 g kg−1 Fe, and 3.0 and 80.0 g kg−1 organic carbon. The dissolved P concentration in pond, dam, and stream water ranged from 0.001 to 4.15 mg L−1 and suspended particulate P (>0.22 µm) ranged from 0.016 to 2.78 mg L−1. Total P in sediments ranged from 29 to 1101 mg kg−1 compared with 134 to 554 mg kg−1 in soils. Inorganic P accounted for 57% of total P in sediments and 75% of total P in soils. Relationships between concentrations of total P, inorganic P, and organic P in sediments and dissolved P in dam water were linear, indicating a buffering action of the sediment constituents on dissolved P. There was a linear relationship between the concentrations of P in sediments and in soils of catchments.
The Efficacy of Polyacrylamide and Related Compounds to Remove Microorganisms and Nutrients from Animal Wastewater
Authors: Entry James A. , Sojka R. E.
Published: July 2010

Polyacrylamide (PAM) is an effective flocculent and we hypothesized that it would reduce transport of microorganisms and nutrients in water flowing over and through soil. We measured nutrients, total coliform bacteria, fecal coliform bacteria, fecal streptococci, active and total fungi, and active and total bacteria in water leached through cattle, fish, and swine manure, PAM, PAM + Al(SO4)3, or PAM + CaO mixtures, and 25‐cm sand columns. In the laboratory study, PAM, PAM + Al(SO4)3, and PAM + CaO treatments reduced total coliform bacteria, fecal coliform bacteria, and fecal streptococci by 10‐ to 1000‐fold in water leached through sand columns. Polyacrylamide + Al(SO4)3 and PAM + CaO treatments reduced the concentration of NH4, total P, and PO4 by 20 to 60% in leachate when cattle and swine manure were applied. In a field study, after water flowed over all three manure sources and then PAM, PAM + Al(SO4)3, or PAM + CaO in furrows, total coliform bacteria, fecal coliform bacteria, and fecal streptococci were reduced by 10‐ to 1000‐fold in water flowing 1 and 27 m downstream of the treatments compared with the control treatment. When water flowed over cattle manure and then PAM + Al(SO4)3 or PAM + CaO, PO4 concentration was reduced by 50 to 70% and total P concentration was reduced by 0 to 75% in water 27 m downstream of the treatments compared with the PAM alone treatment. Polyacrylamide + Al(SO4)3 and PAM + CaO should be able to reduce the numbers of enteric microorganisms and nutrient concentration in animal wastewater running off animal confinement areas, reducing the amount of these pollutants entering surface and ground waters.