bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen availability from peat amendments used in boreal oil sands reclamation
Authors: Hemstock S S , Quideau S A , Chanasyk D S
Published: March 2010

Following surface mining, peat is typically used as an organic amendment to cap reconstructed soils in the Athabasca oil sands region of Alberta. Yet, very little is known about its ability to provide available nitrogen (N) in these soils. Hence, the overall objective of this study was to measure soil nitrogen (N) availability throughout the year in five peat amendments. Specific objectives were: (1) to examine seasonal variability in soil labile N pool sizes (nitrate, ammonium, dissolved organic N, and microbial biomass N), and (2) to determine in situ net nitrification, ammonification, and mineralization rates using the resin-core technique. Results from this field incubation method indicated a strong seasonal variability in net mineralization rates, with maximum positive values in the fall, and low or negative rates in winter. Net ammonification rates, which were significantly correlated to soil moisture content, were significantly smaller and showed smaller seasonal fluctuations and fewer differences among peat materials than net nitrification rates. Furthermore, the contribution of net nitrification to total net mineralization rates was characteristically higher than what is typically observed in undisturbed boreal forest soils. Taken together, results indicate that net nitrification processes may control nitrogen availability in these reclaimed soils.Key words: Soil nitrogen, soil reclamation, nitrification, mineralization, boreal soils
Dissolved soil organic carbon and nitrogen were affected by conversion of native forests to plantations in subtropical China
Authors: Wu J -S , Jiang P -K , Chang S X , Xu Q -F , Lin Y.
Published: March 2010

To better understand the impact of converting native forests to intensively managed plantations on soil carbon (C) and nitrogen (N) dynamics in subtropical China, we examined the seasonal patterns of water-soluble organic C (WSOC) and N (WSON) concentrations in soils in Chinese chestnut (Castanea mollissima Blume) (CF) and bamboo (Phyllostachys praecox C.D. Chu & C.S. Chou) plantation forests (BF) and adjacent native evergreen broadleaf forests (NF) in Ling-long Mountain, Zhejiang Province, China. The plantations were disturbed through surface soil removal and were fertilized and/or mulched, from which economic products (such as nuts and bamboo shoots) were annually harvested. We found that WSOC and WSON had large seasonal variations and were lower in the warmer than in the colder season. Average WSOC concentrations followed the order of BF (58.6) > NF (35.1) > CF (18.1 mg C kg-1), a pattern mainly caused by mulching in BF in winter and the removal of surface soil in CF. Soil total C and N followed the order of BF > NF > CF. The extensive inorganic and organic fertilizer application in BF caused WSON concentrations to be 21 and 14 times higher than those in NF and CF, respectively. Conversion of native forests to plantations lowered soil WSOC:WSON and soil C:N ratios. The seasonal dynamics of WSOC:SOC (soil organic C) and WSON/TN ratios followed the same patterns of WSOC and WSON, respectively. The impacts of forest types on WSOC/SOC ratio, which is a measure of the quality of organic matter, were dependent on seasonal changes of management practices and/or tree growth. Nevertheless mean annual WSON/TN ratios of BF and CF were 2 and 12 times that of NF, indicating that a greater proportion of the total soil N pool became solubilized in the intensively managed plantations. We conclude that land-use conversion and associated management practices had a profound impact on WSOC, WSON, and total C and N concentrations in the studied forest soils in subtropical China.Key words: Forest management, water-soluble organic C, water-soluble organic N, WSOC/WSON ratio
Topographically controlled grassland soils in the Boreal Cordillera ecozone, northwestern Canada
Authors: Sanborn P.
Published: March 2010

Properties and ecological relationships of grassland soils were examined at three widely separated sites (Stikine River Valley, British Columbia, and Carmacks and Kluane Lake, Yukon) in the Boreal Cordillera ecozone of northwestern Canada. At these latitudes (58 to 62°N), grasslands are largely restricted to south-facing aspects, and usually occur as islands within the boreal forest. The grayish and yellowish brown, base-rich, Ah horizons had a thickness-weighted mean organic carbon concentration of 19.5 g kg-1. Ah horizons exhibited a range of microstructures similar to that documented in grassland soils in the southern Cordillera and Great Plains, ranging from spongy to massive in the young loess-derived Kluane Lake pedon to well-developed crumb microstructure in the finer-textured Stikine pedon. These pedons met the morphological and chemical criteria, and likely the soil climate requirements, for the Dark Brown and Brown great groups of the Chernozemic order of the Canadian System of Soil Classification (3rd ed.). Key words: Grassland, Boreal Cordillera, Chernozem, soil micromorphology, soil genesis, soil classification
Development of a method for estimating the likelihood of crack flow in Canadian agricultural soils at the landscape scale
Authors: Dadfar H. , Allaire S E , De Jong R. , van Bochove E. , Denault J -T , Thériault G. , Dechmi F.
Published: March 2010

Indicators of risk of water contamination by agricultural pollutants are developed in Canada to assess sustainability of agriculture. Crack flow (CF), a key pathway for sub-surface contaminant transport, is part of the transport-hydrology algorithm used in two of these risk indicators. The objective was to develop a methodology for predicting the likelihood of CF in Canadian agricultural soils at the landscape scale. The algorithm considers soil clay content, crack development followed by a runoff event based on water budget, tile drainage, and crops. More than 40% of Canadian farmlands had moderate to very high likelihood of CF, mainly in Manitoba, Ontario and Quebec, due to frequent runoffs on cracked clay soils potentially contributing to groundwater contamination. In Ontario and Quebec, farmlands with high CF likelihood correspond to regions under intensive tile drainage, which increases the risk of lateral translocation of contaminants to surface water bodies. Besides being a component of risk indicators of water contamination by phosphorus and coliforms, the CF algorithm and maps can be used to identify areas at risk of subsurface water contamination. Best management practices, adapted to reduce CF can then be targeted to these areas.Key words: Agrichemicals, contaminant transport, macropore flow, preferential flow, risk assessment, risk indicators
Microphysical structure of a developing convective snow cloud simulated by an improved version of the multi‐dimensional bin model
Authors: Misumi Ryohei , Hashimoto Akihiro , Murakami Masataka , Kuba Naomi , Orikasa Narihiro , Saito Atsushi , Tajiri Takuya , Yamashita Katsuya , Chen Jen‐Ping
Published: March 2010

A new version of the multi‐dimensional bin‐microphysics model, which employs four dimensions to represent ice‐particle properties (ice mass, solute mass, aspect ratio and volume), was developed. The model was incorporated into an adiabatic parcel model to simulate the developing stage of a convective snow cloud observed over the Sea of Japan. The results suggest that crystals originating from deposition/condensation–freezing nuclei grow the fastest in the cloud, and isometric crystals among them effectively act as embryos of graupels. Copyright © 2010 Royal Meteorological Society
Pharmacokinetics and pharmacodynamics of controlled release insulin loaded PLGA microcapsules using dry powder inhaler in diabetic rats
Authors: Hamishehkar Hamed , Emami Jaber , Najafabadi Abdolhossien Rouholamini , Gilani Kambiz , Minaiyan Mohsen , Hassanzadeh Kambiz , Mahdavi Hamid , Koohsoltani Maryam , Nokhodchi Ali
Published: March 2010

The pulmonary route is an alternative route of administration for the systemic delivery of peptide and proteins with short‐half lives. A long‐acting formulation of insulin was prepared by encapsulation of protein into respirable, biodegradable microcapsules prepared by an oil in oil emulsification/solvent evaporation method. Insulin‐loaded PLGA microcapsules prepared as a dry powder inhaler formulation were administered via the pulmonary route to diabetic rats and serum insulin and glucose concentrations were monitored. Control treatments consisted of respirable spray‐dried insulin (RSDI) powder administered by intratracheal insufflation, insulin‐loaded PLGA microcapsules and NPH (long‐acting) insulin administered by subcutaneous (SC) administration. Pharmacokinetic analysis demonstrated that insulin administered in PLGA microcapsules illustrated a sustained release profile which resulted in a longer mean residence time, 4 and 5 fold longer than those after pulmonary administration of RSDI and SC injection of NPH insulin, respectively. Accordingly, the hypoglycemic profile followed a stable and sustained pattern which remained constant between 10 and 48 h. Results of the in vitro experiments were in good agreement with those of in vivo studies. Bronchoalveolar lavage fluid analysis indicated that microcapsules administration did not increase the activities of lactate dehydrogenase and total protein. However, histological examination of the lung tissue indicated a minor but detectable effect on the normal physiology of the rat lung. These findings suggest that the encapsulation of peptides and proteins into PLGA microcapsules technique could be a promising controlled delivery system for pulmonary administration. Copyright © 2010 John Wiley & Sons, Ltd.
Proton leak modulation in testicular mitochondria affects reactive oxygen species production and lipid peroxidation
Authors: Rodrigues Ana Sofia , Lacerda Beatriz , Moreno António J. M. , Ramalho‐Santos João
Published: March 2010

Mitochondrial proton leak can account for almost 20% of oxygen consumption and it is generally accepted that this process contributes to basal metabolism. In order to clarify the role of basal proton leak in testicular mitochondria, we performed a comparative study with kidney and liver mitochondrial fractions. Proton leak stimulated by linoleic acid and inhibited by guanosine diphosphate (GDP) was detected, in a manner that was correlated with protein levels for uncoupling protein 2 (UCP2) in the three fractions. Modulation of proton leak had an effect on reactive oxygen species production as well as on lipid peroxidation, and this effect was also tissue‐dependent. However, a possible role for the adenine nucleotide transporter (ANT) in testicular mitochondria proton leak could not be excluded. The modulation of proton leak appears as a possible and attractive target to control oxidative stress with implications for male gametogenesis. Copyright © 2010 John Wiley & Sons, Ltd.
How credible are mining corporations' sustainability reports? a critical analysis of external assurance under the requirements of the international council on mining and metals
Authors: Fonseca Alberto
Published: March 2010

Member companies of the International Council on Mining and Metals (ICMM) have committed to publish externally assured sustainability reports. This paper evaluates the quality of assurance provided to those companies by analyzing the extent to which a sample of their assurance statements met minimum recommended contents. It also seeks to understand the implications of the recently launched ICMM Assurance Procedure. Nine out of the sixteen companies hired assurance in the period analyzed. Their statements mirrored several quality problems highlighted in previous studies. The extensive scope limitations and diversity of verification criteria employed by assurors indicate that mining companies had significant control over the practice. The Assurance Procedure might bring more consistency and breadth to the verification process. The extent to which it will contribute to increased trust in reported information will depend on several factors, including how assurors may interpret the procedure's requirements. Directions for further research are discussed. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment.
Lifetime evaluation in energy‐efficient rectangularad hocwireless networks
Authors: Feng Wei , Elmirghani Jaafar M. H.
Published: March 2010

Ad hocwireless network nodes are typically battery‐powered, therefore energy limit is one of the critical constraints ofad hocwireless networks' development. This paper evaluates the network lifetime of a rectangular network model that achieves energy efficiency by optimizing the node radio range based on the geographical adaptive fidelity (GAF) topology management protocol (Proceedings of ACMMobil'01, July 2001; 70–84). We derive the optimal transmission range of nodes and analyze both static and dynamic traffic scenarios in both equal‐grid and adjustable‐grid rectangular GAF models, where the results show that the adjustable‐grid model saves 78.1% energy in comparison with the minimum energy consumption of equal‐grid model. The impact of node density on both equal‐grid and adjustable‐grid models is investigated to achieve grid‐lifetime balance among all grids to optimize the entire network lifetime. The lifetime estimation results show that without node density control the adjustable‐grid model prolongs the entire network lifetime by a factor of 4.2 compared with the equal‐grid model. Furthermore, the adjustable‐grid model with node density control is able to prolong the entire network lifetime by a factor of 6 compared with the equal‐grid model. Copyright © 2010 John Wiley & Sons, Ltd.
17α-ethinylestradiol induces an imbalance between apoptosis and cell proliferation to sex steroid disruption in a testis culture of gudgeon,Gobio gobio
Authors: Nadzialek Stéphanie , Kestemont Patrick
Published: March 2010

The aim of this study was to investigate the effect of the most potent xenoestrogen currently found in the environment, ethinylestradiol (EE2), on some physiological events occurring during early spermatogenesis of gudgeon (Gobio gobio), a common European fish species. Physiological pathways studies were apoptosis, cell proliferation, and steroidogenesis on sex steroids (testosterone [T], 11-ketotestosterone [11-KT], and 17β-estradiol [E2]). Testis pieces were cultured in vitro during 21 d at 10−4, 10−3, 10−2, 10−1, 1 and 10 µg/L of EE2 as well as in positive (10−1 µg/L of E2) and ethanol control medium. Apoptosis and cell proliferation displayed opposite responses related to the EE2 concentration. When apoptosis inhibition was observed, cell proliferation was induced at 10−2 and 10−1 µg/L of EE2 as well as in the positive control. In contrast, a massive cell death was detected for high EE2 concentrations (1 and 10 µg/L). Steroidogenesis was also disrupted in a dose-related manner. 11-Ketotestosterone was depressed at 10−2 and 10−1 µg/L of EE2 whereas E2 was detectable in the medium only at 10−3, 10−2, and 10−1 µg/L of EE2. High concentrations of T were detected in the medium at 10−3, 10−2, and 10−1 µg/L of EE2 but depressed at 1 and 10 µg/L of EE2. In conclusion, intermediate EE2 concentrations (10−2 and 10−1 µg/L) used in this experimental design have obviously disrupted early spermatogenesis, leading to an imbalance between cell death and cell proliferation in a sex steroid environment toward E2. The results of the present study could be the basis conditions for oocyte development within the testis of a common teleost fish under xenoestrogen exposure. Environ. Toxicol. Chem. 2010;29:881–886. © 2009 SETAC
Influences of soil properties and leaching on copper toxicity to barley root elongation
Authors: Li Bo , Ma Yibing , Mclaughlin Mike J. , Kirby Jason K. , Cozens Gill , Liu Jifang
Published: March 2010

The relationships developed between soil properties and phytotoxicity threshold values for copper require validation in a wide range of soils with different properties and climate characteristics before they can be applied for regulatory purposes in countries throughout the world. Seventeen soils, which are representative of the major soil types and properties in China, were spiked with Cu chloride. A subset of the Cu-spiked soils was leached with artificial rain water to compare toxicity with that in unleached soils. Barley root elongation tests were performed under controlled environmental conditions. The concentrations of added Cu causing a 50% inhibitory effect (EC50) ranged from 67 to 1,129 mg/kg in unleached soils and from 88 to 1,255 mg/kg in leached soil. Compared with the unleached toxicity thresholds, the leached EC10 (10% inhibition) and EC50 were higher by an average of 1.43- and 1.15-fold, respectively. Soil leaching significantly (p ≤ 0.05) decreased the toxicity of Cu in approximately 35% of the soils. In this study, no single soil property was found to explain over 35% of the variance in (log transformed) EC50. However, stepwise multiple regressions using soil pH, organic carbon (OC) content, and effective cation exchange capacity (eCEC) were found to explain over 80% of the variance in Cu toxicity across soils. The model developed for Chinese soils based on these factors was found to predict significantly (r2, 0.90) the phytotoxicity of Cu in European soils. These quantitative relationships between Cu toxicity and soil properties are helpful for developing soil-specific guidance on Cu toxicity thresholds. Environ. Toxicol. Chem. 2010;29:835–842. © 2009 SETAC
Toxicity and biotransformation of uncoated and coated nickel hydroxide nanoparticles on mesquite plants
Authors: Parsons Jason G. , Lopez Martha L. , Gonzalez Christina M. , Peralta-Videa Jose R. , Gardea-Torresdey Jorge L.
Published: March 2010

Nanomaterials are of particular interest in environmental chemistry due to their unknown toxicity to living organisms. Reports indicate that nanoparticles (NPs) affect seed germination, but the uptake and biotransformation of metal nanoparticles is not well understood. The present study investigated the toxicity and biotransformation of Ni(OH)2 NPs by mesquite plants (Prosopis sp.). Three sets of plants were treated for four weeks with 0.01, 0.05, or 0.10 g of either uncoated or sodium citrate coated NPs before and after synthesis. Nickel concentrations in plants were determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and the form and oxidation state of Ni was determined using X-ray absorption spectroscopy (XAS). Results showed that uncoated NPs had an average size of 8.7 nm, whereas coated NPs before and after synthesis had an average of 2.5 and 0.9 nm, respectively. The ICP-OES results showed that plants treated with 0.10 g of uncoated and coated NPs before and after synthesis had 803, 764, and 400 mg Ni kg dry weight, in the leaves, respectively. The XAS analyses showed Ni NPs in roots and shoots of plants treated with uncoated NPs, whereas leaves showed a Ni(II)-organic acid type complex. However, plants treated with coated NPs before or after synthesis showed Ni NPs only in roots and a Ni(II)-organic acid complex in shoots and leaves. Results also showed that none of the treatments reduced plant size or chlorophyll production. To the authors' knowledge, this is the first time that the biotransformation of nanoparticles by a plant system is reported. Environ. Toxicol. Chem. 2010;29:1146–1154. © 2010 SETAC
Multimedia modeling of human exposure to chemical substances: The roles of food web biomagnification and biotransformation
Authors: Arnot Jon A. , Mackay Don , Parkerton Thomas F. , Zaleski Rosemary T. , Warren Christopher S.
Published: March 2010

The Risk Assessment IDentification And Ranking (RAIDAR) model is refined to calculate relative human exposures as expressed by total intake, intake fraction (iF), and total body burden (TBB) metrics. The RAIDAR model is applied to three persistent organic pollutants (POPs) and six petrochemicals using four mode-of-entry emission scenarios to evaluate the effect of metabolic biotransformation estimates on human exposure calculations. When biotransformation rates are assumed to be negligible, daily intake and iFs for the nine substances ranged over six orders of magnitude and TBBs ranged over 10 orders of magnitude. Including biotransformation estimates for fish, birds, and mammals reduced substance-specific daily intake and iF by up to 4.5 orders of magnitude and TBB by more than eight orders of magnitude. The RAIDAR iF calculations are compared to the European Union System for the Evaluation of Substances (EUSES) model iF calculations and differences are discussed, especially the treatment of food web bioaccumulation. Model selection and application assumptions result in different rankings of human exposure potential. These results suggest a need to critically consider model selection and to include reliable biotransformation rate estimates when assessing relative human exposure and ranking substances for priority setting. Recommendations for further model evaluations and revisions are discussed. Environ. Toxicol. Chem. 2010;29:45–55. © 2009 SETAC
Toxicity of the herbicides bromacil and simazine to the aquatic macrophyte, Vallisneria americana Michx
Authors: Wilson P. Chris , Wilson Sandra B.
Published: March 2010

Vallisneria americana Michx. (tapegrass) is an ecologically important submersed, vascular aquatic plant that provides food and shelter for many aquatic and waterfowl species. This plant often occurs close to land areas where herbicides are used. Nontarget exposure of these plants to herbicides may compromise ecological structure and function. The objective of the present study was to evaluate the suitability of several endpoint measurements for determining no-observable-adverse effect concentrations (NOAECs), lowest-observable-adverse effect concentrations (LOAECs), and median effective concentration values (EC50s) for tapegrass exposed to the herbicides bromacil (0–0.092 mg/L) and simazine (0–0.592 mg/L) following a 13-d single-pulse exposure and 15-d (bromacil) or 14-d (simazine) postexposure periods. The NOAEC/LOAEC/EC50 for fresh weight gains, new leaf production, and total leaf growth after 13-d exposure to bromacil were 0.020/0.036/0.032, 0.036/0.054/0.036, and 0.036/0.054/0.043 mg/L, respectively. The same respective NOAEC/LOAEC/EC50s for simazine were <0.058/0.058/0.067, 0.229/0.344/0.154, and 0.058/0.116/0.081 mg/L. Reductions in quantity and fresh weight of daughter plants produced and stolon fresh weights occurred at bromacil concentrations ≥0.077, 0.020, and 0.036 mg/L, respectively; and simazine concentrations ≥0.344, >0.592, and ≥0.116 mg/L, respectively. Neither herbicide affected leaf greenness, total chlorophyll concentrations, or carbohydrate allocation. Although toxicity was shown for many endpoints, most EC50 values were greater than aquatic life benchmark values for algae used by the U.S. Environmental Protection Agency (U.S. EPA), but less than for aquatic plants, indicating that V. americana would likely be protected by use of the algal benchmark criteria. Environ. Toxicol. Chem. 2010;29:201–211. © 2009 SETAC
An evaluation of mercury concentrations in three brands of canned tuna
Authors: Gerstenberger Shawn L. , Martinson Adam , Kramer Joanna L.
Published: March 2010

There is widespread concern over the presence of Hg in fish consumed by humans. While studies have been focused on determining the Hg concentration in sport fish and some commercial fish, little attention has been directed to canned tuna; it is widely held that concentrations are low. In the present study, the amount of Hg present in canned tuna purchased in Las Vegas, Nevada, USA, was examined, and the brand, temporal variation, type, and packaging medium impacts on Hg concentrations in tuna were explored. A significant (p < 0.001) brand difference was noted: Brand 3 contained higher Hg concentrations ( standard deviation (SD) (0.777 ± 0.320 ppm) than Brands 1 (0.541 ± 0.114 ppm) and 2 (0.550 ± 0.199 ppm). Chunk white tuna (0.619 ± 0.212 ppm) and solid white tuna (0.576 ± 0.178 ppm) were both significantly (p < 0.001) higher in mean Hg than chunk light tuna (0.137 ± 0.063 ppm). No significant temporal variation was noted, and packaging had no significant effect on Hg concentration. In total, 55% of all tuna examined was above the U.S. Environmental Protection Agency's (U.S. EPA) safety level for human consumption (0.5 ppm), and 5% of the tuna exceeded the action level established by the U.S. Food and Drug Administration (U.S. FDA) (1.0 ppm). These results indicate that stricter regulation of the canned tuna industry is necessary to ensure the safety of sensitive populations such as pregnant women, infants, and children. According to the U.S. EPA reference dose of 0.1 µg/kg body weight per day and a mean Hg value of 0.619 ppm, a 25-kg child may consume a meal (75 g) of canned chunk white tuna only once every 18.6 d. Continued monitoring of the industry and efforts to reduce Hg concentrations in canned tuna are recommended. Environ. Toxicol. Chem. 2010;29:237–242. © 2009 SETAC
Arsenic in Lake Lansing, michigan
Authors: Batterson Ted R. , McNabb Clarence D.
Published: March 2010

Lake Lansing was treated with sodium arsenite for macrophyte control in 1957. Two 2.5-m cores from deep portions of the basin showed the historical consequence of this treatment. Maxima of 330–340 μg As g−1 dry weight occurred at a depth interval of 0.15–0.30 m; background was 17–20 ppm As. An arsenic mass balance budget for the lake for June 1978 to June 1979 showed it lost more arsenic than it received. Internal loading of the water from the sediments was occurring; > 85% of the area of surficial sediments had concentrations two to six times background. From laboratory experiments, we hypothesize Fe3+ controls arsenic concentration over aerobic sediments; As(III) increases in anoxic water with conversion of Fe3+ to Fe2+ and As(V) to As(III) at the sediment surface. As(III) in water diminishes during prolonged anoxia by reaction with S2−. As(III) and Fe2+ are oxidized upon aeration of anoxic water, and As(V) is taken out of solution with ferric iron in a manner similar to phosphate. Arsenic concentrations observed in the lake over an annual cycle fit these expectations.
Comparative toxicology of mirex, photomirex and chlordecone after oral administration to the mouse
Authors: Fujimori K. , Ho I. K. , Mehendale H. M. , Villeneuve D.C.
Published: March 2010

The toxicities of chlordecone (CD), mirex (M) and photomirex (PM) were compared in the male mouse after daily oral administration of 10 mg/kg in corn oil vehicle (10 ml/kg). Mortality occurred starting day 10 with M, and day 16 with PM and CD, and LT50 values were 132, 265 and 254 mg/kg, respectively. However the LT50 values of M, PM or CD were not different (range, 100–125 mg/kg) when animals were intubated with the compounds daily at 25 or 50 mg/kg. Food and water consumption and body weight were decreased after M, but PM and CD increased these parameters. Other symptoms of toxicity included severe diarrhea with M, whereas a moderate diarrhea occurred with PM and little or no diarrhea with CD. The effects of M, PM or CD on the hepatic microsomal mixed function oxidase system were compared 4 d after the administration of 10 mg/kg/d of these compounds. M and PM were equipotent, whereas CD was found to be approximately half as effective in inducing cytochrome P-450 and associated enzyme activities. CD and M caused a decrease in blood glucose levels due to enhanced oxidation, since liver glycogen levels were also reduced. CD-induced tremors could not be prevented by restoring the blood glucose level. CD levels in liver, muscle, whole brain and plasma were several-fold higher than for either M or PM. These results suggest that although structurally similar, these three analogs differ significantly in their biological effects.
The effects of a chronic mercury exposure on survival, reproduction and population dynamics of Mysidopsis Bahia
Authors: Gentile J. H. , Gentile S. M. , Hoffman G. , Heltshe J. F. , Hairston N.
Published: March 2010

The epibenthic mysid Mysidopsis bahia was chronically exposed throughout its entire life cycle to inorganic mercury. The experimental design permitted the precise measurements of survival rates; individual and population growth rates; and sublethal reproductive responses, including time to sexual maturation and first brood release, egg development time, brood size and frequency of reproduction. Mercury was acutely toxic (96-h LC50) to juveniles at 3.5 μg L−1, chronically toxic (35-d LC50) at 1.8 μg L−1 and differentially toxic to males and females (α = 0.05). Male and female mortality rates were 35 and 18%, respectively, from sexual maturation (day 14) through termination of the assay (day 35). Reproductive effects included delays in sexual maturation and brood release at 1.6 μg L−1, a doubling of brood development time at 2.5 μg L−1 and subsequent abortion and significant decreases in the total broods released (and therefore juveniles produced) at 1.6 μg L−1. Intrinsic rates of population increase (r), calculated from life-tables, decreased with increasing mercury concentration. The critical value (r = 0) for mercury occurs at 1.6 μg L−1, which corresponds well with the upper limit of the maximum acceptable toxicant concentration, the usual endpoint of life-cycle toxicity tests. The toxicity test system is a sensitive, precise model for studying lethal, sublethal and potential population consequences of pollution.
Relative sensitivity of Daphnia Magna, rainbow trout and fathead minnows to endosulfan
Authors: Nebeker Aaln V. , McCrady Joel K. , Mshar Roger , McAuliffe Chris K.
Published: March 2010

Flow-through and static tests were conducted with fathead minnows, rainbow trout and Daphnia magna to determine their relative sensitivities to measured concentrations of the insecticide endosulfan and to compare responses of fish in replicated static and flow-through exposure procedures. Fathead minnow 96-h static LC50 values were 1.3, 0.8 and 1.3 μg/L endosulfan. The 96-h LC50 values for fatheads in flow-through tests were 1.7 and 1.0 μg/L. Rainbow trout 96-h static LC50 values were 1.7 and 1.6 μg/L. The 96-h LC50 values for rainbows in flow-through tests were 0.3 and 0.4 μg/L. Acute 48-h static EC50 values for D. magna were 343 and 271 μg/L endosulfan. These results suggest that differences in species sensitivity can be as great as three orders of magnitude.
Toxicity of silver to steelhead and rainbow trout, fathead minnows and Daphnia Magna
Authors: Nebeker Alan V. , McAuliffe Chris K. , Mshar Roger , Stevens Donald G.
Published: March 2010

Rainbow (Salmo gairdneri) and steelhead (Salmogairdneri) trout and fathead minnows (Pimephales promelas) were exposed to silver for 96 h in replicated flow-through tests. Rainbow trout, fathead minnows and Daphnia magna were exposed to silver in replicated static acute tests. Steelhead trout embryo-larval stages were tested in a flow-through system for 60 d, and D. magna were exposed through complete life cycles in replicated static-renewal tests. All silver concentrations were measured values. No differences were seen between flow-through and static LC50 values. Rainbow trout 96-h flow-through LC50 values were 8.6 and 9.7 μg/L silver; static values were 10.9 and 8.5 μg/L. The 96-h LC50 for steelhead trout in the flow-through test was 9.2 μg/L. Fathead minnow 96-h flow-through LC50 values were 5.6 and 7.4 μg/L silver; static values were 9.4 and 9.7 μg/L. The absence of food in static tests with D. magna caused silver to be about 10 times more toxic; the 48-h static mean EC50 value for D. magna without food was 0.9 μg/L, compared to 12.5 μg/L in the test with food. The early-life-stage test with steelhead trout, from newly fertilized eggs to post-swimup juveniles, showed complete mortality at 1.3 μg/L and significant reduction in fish survival at 0.5 μg/L silver. Mean weight and length at end of test were greatly reduced at 1.1 μg/L, and were significantly different from controls at 0.1 μg/L. The mean 21-d EC50 value for the D. magna test with food was 3.5 μg/L. The 21-d lowest significant (α = 0.05) effect on survival occurred at 4.1 μg/L. The mean silver concentration at which there was a significant decrease in total Daphnia young/female/day after 21 d, compared to the control was 10.5 μg/L silver.
Evaluation and development of static shake-flask biodegradation test systems
Authors: Blum James E. , Stevenson Cathy A. , Stainken Dennis M.
Published: March 2010

Several biodegradation flask systems were evaluated to assess the effects of flask shape and volume and length of incubation on the recovery of 14CO2. During a 6-h incubation period, it was demonstrated that the recovery of 14 CO2 decreased as the volume of the flask (50 ml to 2 L) and the length of the diffusion path increased. Increasing the incubation time improved the performance of flasks, which were relatively inefficient at 6 h. Selected flask systems were further assessed, measuring the extent of CO2 evolution from nonradiolabeled linear alkylate sulfonate and glucose by a mixed inoculum.
Use of microcosms to study transport, transformation and fate of organics in aquatic systems
Authors: Rodgers John H. , Dickson Kenneth L. , Saleh Farida Y. , Staples Charles A.
Published: March 2010

Assessing the hazards of chemicals in aquatic ecosystems requires methods for examining where a potential toxicant is likely to be in place, time, form and concentration. Currently there is considerable interest in the use of microcosms as predictors of transport, transformation and fate of potentially toxic organics in aquatic systems. Generic microcosms of varying complexity can serve as useful tools for studying partitioning and kinetics of organic chemicals. Microcosms facilitate determination of mass balances and recovery of transformation products for further study. In this study, extensively characterized generic microcosms were used to examine the fates of naphthalene and lindane, and to compare observed compartmentalization and processing to predictions by two fate models, the Exposure Analysis Modeling System (EXAMS) and Simplified Lake and Stream Analysis (SLSA). Inputs to the fate models consisted of microcosm characteristics and laboratory-determined rate coefficients for the two chemicals. Both fate models demonstrated good capabilities for predicting aqueous phase concentrations of naphthalene and lindane. However, EXAMS and SLSA predicted sediment naphthalene and lindane concentrations that exceeded observed concentrations by up to two orders of magnitude. This lack of agreement for sediments may be attributed to model inputs or model constructs. Sediments deserve further attention, since many organic chemicals of environmental concern have relatively large sediment-water partition coefficients and are not biodegraded at an appreciable rate. Both the questions of depth distribution of chemicals through time and sediment microbial degradation rates need further study, since the understanding of them may enhance model development. Depending upon the question or the hypothesis addressed, microcosm construction may range from simple to complex with one to several compartments. Through careful microcosm design, processes controlling the fate of a particular chemical in nature may be isolated and examined in detail. Fates of a variety of chemicals can be compared and contrasted efficiently in replicate microcosms. As simplified systems, microcosms are accurate predictors only for those processes and equilibrium phenomena that are sufficiently understood to scale to natural systems. Microcosms can provide feedback information for theoretical model testing and validation.
Fate of methyl parathion in aquatic channel microcosms
Authors: Holm H. W. , Kollig H. P. , Payne W. R. , Proctor L. M.
Published: March 2010

The fate of methyl parathion and the development of biological communities were examined as a function of inorganic nutrient enrichment, inorganic nutrients plus glycerol and presence of sediments in two eight-compartment, continuous-flow channel microcosms. First-order degradation rates of methyl parathion were related to the different nutrient treatments, with higher rates associated with the organically enriched environments. A stable state was generally established in each compartment after 6 weeks of development. Aufwuchs biomass dominated the systems and observed differences (α = 0.10) in nutrient concentrations were reflected by differences (α = 0.05) in some aufwuchs structural parameters and in community function. Inclusion of sediments had no significant effect on any of the parameters measured.
Potential terrestrial fate and effects on soil biota of a coal liquefaction product spill
Authors: Strayer Richard F. , Edwards Nelson T. , Walton Barbara T. , Charles-Shannon Velma
Published: March 2010

Contaminated soil samples collected from the site of a coal liquefaction product spill were used to study potential fates and effects of this synthetic fuel. Simulated weathering in the laboratory caused significant changes in residual oil composition. Soil column leachates contained high phenol levels that decreased exponentially over time. Toxicity tests demonstrated that the oil-contaminated soil was phytotoxic and caused embryotoxic and teratogenic effects on eggs of the cricket Acheta domesticus.
Toxicity of creosote-contaminated sediment to field- and laboratory-colonized estuarine benthic communities
Authors: Tagatz Marlin E. , Plaia Gayle R. , Deans Christine H. , Lores Emile M.
Published: March 2010

Macrobenthic animal communities that colonized uncontaminated and creosote-contaminated sand (177, 844 and 4,420 μg/g, nominal) during 8 weeks were compared to assess effects of marine-grade creosote on community structure. Aquaria were colonized in the laboratory by planktonic larvae entrained in continuously supplied unfiltered seawater and in the field by animals that occurred naturally. Individuals and species in aquaria that contained 844 and 4,420 μg creosote/g sand were significantly fewer (α = 0.05) than those in the control. Abundance of animals in field-colonized communities contaminated with 177 μg/g creosote, but not in laboratory-colonized communities, also was less than that in the control. The lowest creosote concentration at either site that affected numbers of individuals or species was 844 μg/g for mollusks and 177 μg/g for echinoderms, annelids and arthropods. The Shannon-Weaver index of diversity, Simpson's index of dominance and the Bray-Curtis dissimilarity index differences were greater with each increase in creosote concentration. Rarefaction indices of diversity indicated that the distribution of individuals within species was about the same for laboratory and field assemblages of animals. Initial measured concentrations of creosote in sand (midrange concentration) decreased by 30% in the laboratory and by 42% in the field at the end of the 8-week test.
Fate and speciation of silver in publicly owned treatment works
Authors: Lytle Paul E.
Published: March 2010

The fate and speciation of silver in three categories of publicly owned treatment works and their receiving waters were studied. The plants included those that treated (a) municipal sewage and commercial photoprocessing effluents, (b) municipal sewage and nonphotographic silver effluents and (c) municipal sewage with no known silver effluents. Specific objectives were to determine if the source of silver affects silver removal and how secondary treatment affects the speciation of silver.

The average removal efficiency for total silver at the six treatment plants studied was 75%. The two plants receiving silver from photoprocessing operations achieved 95% removal. The two plants receiving silver from industrial sources achieved 83% removal. The plants with no known silver contributors achieved 48% removal. There was no significant increase in silver in any of the sediments downstream of the treatment plant discharges.

The highest influent free silver ion concentrations were associated with the treatment plants that had no known photoprocessing or industrial silver sources. The concentrations of silver ion in the effluents from all treatment plants ranged from 0.001 to 0.07 μg/L. Downstream silver ion concentrations were always ≤ 0.05 μg/L. With the chronic toxicity value to freshwater aquatic life for silver ion being stated as 0.12 μg/L, the relatively small quantities of silver ion and total silver that were discharged should have little, if any, impact on receiving water quality.
The influence of speciation on the toxicity of silver to fathead minnow (Pimephales promelas)
Authors: Leblanc Gerald A , Mastone Joseph D , Paradice Arthur P , Wilson Brenda F , Jr Haines B Lockhart , Robillard Kenneth A
Published: March 2010

Silver sulfide, silver thiosulfate complex and silver chloride complexes were tested and compared with free silver ion for their toxic effects in 96 h flow through acute toxicity tests using fathead minnows (Pimephales promelas). Thirty day fathead minnow embryo larval tests were conducted with silver sulfide and silver thiosulfate complex. Extensive chemical analyses were performed to quantify actual exposures. Compared with free silver ion, silver chloride complexes were about 300 times less toxic acutely silver sulfide was at least 15,000 times less toxic acutely and silver thiosulfate complex was more than 17,500 times less toxic acutely. The estimated maximum acceptable toxicant concentrations (MATCs) determined from the embryo larval tests with silver sulfide and silver thiosulfate complex were greater than 11 mg/L (as total silver) and greater than 16 but less than 35 mg/L (as total silver), respectively. The MATC previously reported for free silver ion from tests with rainbow trout (Salmo gairdneri) was greater than 0 00009 but less than 0 00017 mg/L. These differences in acute toxicities and the differences of five orders of magnitude in the MATC values are attributed to the influence of chemical speciation on the effects of silver in the aquatic environment. Thus, the speciation of silver is an essential factor in its potential to affect fish and, presumably, other aquatic life, and therefore should be considered in environmental risk assessment.
Relative toxicities of chemicals to the earthworm Eisenia foetida
Authors: Roberts Brian L. , Wyman Dorough H.
Published: March 2010

In the present study, 90 chemicals were tested against Eisenia foetida for the purpose of using this organism as the marker species to indicate the relative toxicities of chemicals to earthworms and other soil invertebrates. The worms were exposed to deposits of the chemicals on filter paper for 48 h and the mortality was recorded; concentrations were expressed in μg/cm2. Based on the resulting LC50 values, the chemicals were classified as supertoxic (< 1.0 μg/cm2), extremely toxic (1–10 μg/cm2), very toxic (10–100 μg/cm2), moderately toxic (100–1,000 μg/cm2) or relatively nontoxic (> 1,000 μg/cm2). Of the chemicals tested (pesticides, solvents, metals, drugs, carcinogens, etc.), only carbofuran and eserine salicylate, both carbamates, were supertoxic. The remaining chemicals were distributed about equally among the other toxicity categories. The most surprising results were that the phenolic hydrolytic products of parathion, carbaryl, 2,4-D and 2,4,5-T were as toxic, or more toxic, than the parent material, with all of these compounds falling within the extremely toxic and very toxic classifications. Several chemicals, considered only moderately or relatively nontoxic to mammals, were extremely or very toxic to earthworms; among these compounds were carbaryl, malathion, cypermethrin and benomyl. The results of this study further demonstrate the unpredictability of chemical toxicity to different animal species, a fact which complicates the assessment of environmental risk to one or more species based on data attained with another.
The effect of naphthalene on oxygen consumption and hemoglobin concentration in Chironomus attenuatus and on oxygen consumption and life cycle of Tanytarsus dissimilis
Authors: Darville Roy G. , Wilhm Jerry L.
Published: March 2010

The effects of naphthalene on the physiology and life cycle of two species of benthic macroinvertebrates, Chironomus attenuatus and Tanytarsus dissimilis (Diptera: Chironomidae), were determined. The acute effects measured were survival, oxygen consumption, hemoglobin concentration and total body glycogen content. A flow-through system was used to determine chronic effects on life cycle and reproduction parameters.

Both species had LC50 values of approximately 13 mg/L. After exposure to naphthalene for 1 h, the oxygen consumption of both species decreased. Tanytarsus was more sensitive than Chironomus, which is consistent with the life histories of the two species. The decrease in oxygen uptake was due to inhibition of the electron transport chain or interference with functioning of the nervous system.

Hemoglobin concentrations in Chironomus were not good indicators of naphthalene stress. Although hemoglobin in Chironomus decreased after 4 h of exposure, the decrease was not significant. The decrease could not be accounted for by alteration of hemoglobin structure or by inhibition of synthesis.

Life cycle exposures at naphthalene concentrations of less than 0.5 mg/L resulted in minimal effects. Egg hatching and adult emergence were the best indicators of chronic exposure. Pupation times and numbers of eggs were not significantly changed.
Effects of freshwater exposure to arsenic trioxide on the parr-smolt transformation of coho salmon (Oncorhynchus kisutch)
Authors: Nichols John W. , Wedemeyer Gary A. , Mayer Foster L. , Dickhoff Walton W. , Gregory Stan V. , Yasutake William T. , Smith Stanley D.
Published: March 2010

The effects of chronic (6 months) exposure to arsenic trioxide in fresh water on the Parr-smolt transformation of coho salmon (Oncorhynchus kisutch) were evaluated. Exposure to 300 μg As/L (as As2O3) appeared to delay the onset of the normal increase in plasma thyroxine concentration and cause a transient reduction of gill Na+,K+-ATPase activity. Fish exposed to 300 μg As/L also migrated to the sea less successfully than did nonexposed smolts, but there were no effects on the survival and growth of smolts held in 28‰ salt water for 6 months.
A quantitative correlation of the LC50 values of esters in pimephales promelas using physicochemical and topological parameters
Authors: Basak S. C. , Gieschen D. P. , Magnuson V. R.
Published: March 2010

In recent years much emphasis has been given to the development of easily calculated molecular descriptors that can adequately predict the pharmacological and toxic action of bioactive molecules. In this article a quantitative structure-activity relationship (QSAR) study of industrially important esters was carried out using hydrophobicity (log P, octanol-water), molecular connectivity indices (lX, lXv), Wiener number (W) and information-theoretic topological indices defined on the total molecular graph. Information-theoretic topological indices studied include information content (IC), structural information content (SIC) and complementary information content (CIC), as well as information indices derived from the distance matrix of the hydrogen-suppressed chemical graph (IWD, I  WD). The topological index lXv, an electronic parameter, was found to be the single best descriptor for predicting the LC50 values of esters in Pimephales promelas. However, a multiparametric relationship including a lipophilic (log P), an electronic (lXv) and a steric (CIC) parameter resulted in the most significant correlation, suggesting multiconditionality in the mode of toxic action of these esters.