pinecone/core-2020-05-10-deduplication huggingface dataset:
A laboratory and in situ postexposure feeding assay with a freshwater snail

Contaminant-driven feeding inhibition has direct and immediate consequences at higher levels of biological organization, by
depressing the population consumption and thus hampering ecosystem functioning (e.g., grazing, organic matter decomposition). The
present study aimed at developing a short-term laboratory and in situ assay based on the postexposure feeding of the freshwater snail
Theodoxus fluviatilis. A method to precisely quantify feeding rates was first developed, consisting of a 3-h feeding period, in darkness, on
150 defrosted nauplii of the brine shrimp Artemia franciscana. Postexposure feeding after a 48-h exposure to cadmium was approximately
as sensitive as survival, with the median effective concentration (EC50) and median lethal concentration (LC50) being 85 mg/L and
102 mg/L, respectively, and the 20% effective concentration (EC20) and 20% lethal concentration (LC20) being 41 mg/L and 77 mg/L,
respectively. Together, both effects at the LC20 reduced population consumption by 56%. In situ experiments at reference sites covering
broad ranges of current velocity, hardness, conductivity, sediment organic matter content, and sediment particle size distribution revealed
the influence of these abiotic conditions on postexposure feeding, in the absence of contamination, to be negligible. The effectiveness of
the in situ assay was evaluated at 5 sites contaminated with acid mine drainage. Surviving organisms at the single partially lethal site (37%
mortality) presented a 54% feeding inhibition relative to the reference, whereas the population consumption would be inhibited by 71%,
confirming the integration of survival and feeding to be pertinent for estimating contaminant effects at higher levels of biological
organization.The present study was funded by the Fundação para a
Ciência e a Tecnologia (Portugal) through the FRAMEFFECTIVE and
ECOTOXTOOLS projects (contracts PTDC/AAC-AMB/105411/2008 and
PTDC/AAC-AMB/103547/2008, respectively) and through Ciência 2007—
Human Potential Operational Program and Quadro de Referência Estrat egico
Nacional through European Social Fund and Ministry of Education and
Science funds
Predicting concentrations of the cytostatic drugs cyclophosphamide, carboplatin, 5-fluorouracil, and capecitabine throughout the sewage effluents and surface waters of Europe

The present study evaluated the potential environmental concentrations of 4 cytostatic (also known as cytotoxic) drugs in rivers. The antimetabolite 5-fluorouracil (5FU) and its pro-drug capecitabine were examined based on their very high use rates, cyclophosphamide (CP) for its persistence, and carboplatin for its association with the metal element platinum. The study combined drug consumption information across European countries, excretion, national water use, and sewage removal rates to derive sewage effluent values across the continent. Results showed considerable variation in the popularity of individual cytostatic drugs across Europe, including a 28-fold difference in 5FU use and 15-fold difference in CP use. Such variations could have a major effect on the detection of these compounds in effluent or river water. Overall, capecitabine and CP had higher predicted levels in effluent than 5FU or carboplatin. Predicted effluent values were compared with measurements in the literature, and many non-detects could be explained by insufficient limits of detection. Linking the geographic based water resources model GWAVA with this information allowed water concentrations throughout 1.2 million km of European rivers to be predicted. The 90th percentile (worst case) prediction indicated that, with the exception of capecitabine, more than 99% of Europe's rivers (by length) would have concentrations below 1 ng/L for these cytostatic drugs. For capecitabine, 2.2% of river length could exceed 1 ng/L
Application of mercury isotopes for tracing trophic transfer and internal distribution of mercury in marine fish feeding experiments

Feeding experiments were performed to investigate mercury (Hg) isotope fractionation during trophic transfer and internal distribution of total Hg (THg) in marine fish on exposure to natural seafood. Young‐of‐the‐year amberjack ( Seriola dumerili ) were fed with either blackfin tuna ( Thunnus atlanticus ; 2647 ng/g THg) or brown shrimp ( Farfantepenaeus aztecus ; 25.1 ng/g THg) for 80 d or 50 d, respectively, and dissected for muscle, liver, kidney, brain, and blood. After 30 d of tuna consumption, Hg isotopes (δ 202 Hg and Δ 199 Hg) of the amberjack organs shifted to the tuna value (δ 202 Hg = 0.55‰, Δ 199 Hg = 1.54‰,), demonstrating the absence of Hg isotope fractionation. When amberjack were fed a shrimp diet, there was an initial mixing of the amberjack organs toward the shrimp value (δ 202 Hg = −0.48‰, Δ 199 Hg = 0.32‰), followed by a cessation of further shifts in Δ 199 Hg and a small shift in δ 202 Hg. The failure of Δ 199 Hg to reach the shrimp value can be attributed to a reduction in Hg bioaccumulation from shrimp resulting from feeding inhibition and the δ 202 Hg shift can be attributed to a small internal fractionation during excretion. Given that the feeding rate and Hg concentration of the diet can influence internal Hg isotope distribution, these parameters must be considered in biosentinel fish studies.  Environ Toxicol Chem  2013;32:2322–2330. © 2013 SETA
Influence of soil pH on the toxicity of zinc oxide nanoparticles to the terrestrial isopod Porcellionides pruinosus

The effects of soil pH on the toxicity of ZnO nanoparticles (NPs) to the terrestrial isopod Porcellionides pruinosus were evaluated. Isopods were exposed to a natural soil amended with CaCO3 to reach 3 different pHCaCl2 levels (4.5, 6.2, and 7.3) and to standard LUFA 2.2 soil (pH 5.5) spiked with ZnO NPs (30 nm), non-nano ZnO (200 nm), and ionic Zn as ZnCl2. Toxicity was expressed based on total Zn concentration in soil, as well as total Zn and free Zn2+ ion concentrations in porewater. Compared with ZnO-spiked soils, the ZnCl2-spiked soils had lower pH and higher porewater Ca2+ and Zn levels. Isopod survival did not differ between Zn forms and soils, but survival was higher for isopods exposed to ZnO NPs at pH 4.5. Median effect concentrations (EC50s) for biomass change showed similar trends for all Zn forms in all soils, with higher values at intermediate pH. Median lethal concentration (LC50) and EC50 values based on porewater Zn or free Zn ion concentrations were much lower for ZnO than for ionic zinc. Zn body concentrations increased in a dose-related manner, but no effect of soil pH was found. It is suggested not only that dissolved or free Zn in porewater contributed to uptake and toxicity, but also that oral uptake (i.e., ingestion of soil particles) could be an important additional route of exposure
Global change and mercury cycling: Challenges for implementing a global mercury treaty

The Minamata Convention aims to protect human health and the environment from anthropogenic emissions and releases of mercury. In the present study, the provisions of the Minamata Convention are examined to assess their influence on global biogeochemical cycling of Hg. Although the convention's scope covers all major categories of atmospheric emissions, the degree to which it will affect future emissions trajectories remains unclear. A box model analysis shows that future global biogeochemical cycling under projected technological provisions would result mainly in avoided increases and that estimated differences in atmospheric concentrations resulting from policies would be on the order of 1% to 2% per year. Present experience suggests that scientific knowledge is not currently sufficient to attribute causes to changes of this magnitude. Enhancements to capacity to measure the effectiveness of the Minamata Convention are suggested, including both measurement and modeling.National Science Foundation (U.S.) (Atmospheric Chemistry Program Award 1053648
Cadmium toxicity on the freshwater microalga Chlamydomonas moewusii Gerloff: Biosynthesis of thiol compounds

Cadmium (Cd) toxicity and production of different thiols (phytochelatins, glutathione, γ-Glu-Cys and cysteine) were studied in the microalga Chlamydomonas moewusii exposed to different concentrations of this metal (1, 2, 4, 6, 8, and 10 mg/L) for 96 h. The inhibitory effect of Cd on growth was demonstrated. The value of EC50 (metal concentration which reduces the population growth to 50% of the control) obtained for this microalga was estimated at 4.1 ± 0.8 mg/L of Cd after 96 h of exposure. The amount of thiol compounds synthesized by C. moewusii changed with Cd concentration. Cysteine concentrations were significantly higher compared to those of γ-Glu-Cys and glutathione in all the Cd concentrations assayed. The amino acid cysteine reached its higher levels in those cultures in which a decrease in the concentration of phytochelatins (PCs) was observed. Both cysteine and glutathione concentrations showed significant differences along the Cd concentrations assayed, while the amount of γ-Glu-Cys detected remained stable. The PCs detected were of two, three, and four subunits. The level of PC2 was higher than that of PC3 and PC4. PC4 was detected only in the cultures exposed to the Cd concentrations of 1 and 2 mg/L, in which the synthesis of phytochelatins was higher. A rapid increase in the production of PC2 and PC3 was observed up to a Cd concentration of 2 mg/L, after which their levels began to decrease. Phytochelatins were not detected in cultures without Cd (controls) and in those exposed to the maximum Cd concentration (10 mg/L), in which cell growth was completely inhibite
The rhizotoxicity of metal cations is related to their strength of binding to hard ligands

Mechanisms whereby metal cations are toxic to plant roots remain largely unknown. Aluminum, for example, has been recognized as rhizotoxic for approximately 100 yr, but there is no consensus on its mode of action. The authors contend that the primary mechanism of rhizotoxicity of many metal cations is nonspecific and that the magnitude of toxic effects is positively related to the strength with which they bind to hard ligands, especially carboxylate ligands of the cell-wall pectic matrix. Specifically, the authors propose that metal cations have a common toxic mechanism through inhibiting the controlled relaxation of the cell wall as required for elongation. Metal cations such as Al3+ and Hg2+, which bind strongly to hard ligands, are toxic at relatively low concentrations because they bind strongly to the walls of cells in the rhizodermis and outer cortex of the root elongation zone with little movement into the inner tissues. In contrast, metal cations such as Ca2+, Na+, Mn2+, and Zn2+, which bind weakly to hard ligands, bind only weakly to the cell wall and move farther into the root cylinder. Only at high concentrations is their weak binding sufficient to inhibit the relaxation of the cell wall. Finally, different mechanisms would explain why certain metal cations (for example, Tl+, Ag+, Cs+, and Cu2+) are sometimes more toxic than expected through binding to hard ligands. The data presented in the present study demonstrate the importance of strength of binding to hard ligands in influencing a range of important physiological processes within roots through nonspecific mechanisms
Worldwide estimation of river concentrations of any chemical originating from sewage-treatment plants using dilution factors\ud

Dilution factors are a critical component in estimating concentrations of so-called “down-the-drain” chemicals (e.g., pharmaceuticals) in rivers. The present study estimated the temporal and spatial variability of dilution factors around the world using geographically referenced data sets at 0.5° × 0.5° resolution. Domestic wastewater effluents were derived from national per capita domestic water use estimates and gridded population. Monthly and annual river flows were estimated by accumulating runoff estimates using topographically derived flow directions. National statistics, including the median and interquartile range, were generated to quantify dilution factors. Spatial variability of the dilution factor was found to be considerable; for example, there are 4 orders of magnitude in annual median dilution factor between Canada and Morocco. Temporal variability within a country can also be substantial; in India, there are up to 9 orders of magnitude between median monthly dilution factors. These national statistics provide a global picture of the temporal and spatial variability of dilution factors and, hence, of the potential exposure to down-the-drain chemicals. The present methodology has potential for a wide international community (including decision makers and pharmaceutical companies) to assess relative exposure to down-the-drain chemicals released by human pollution in rivers and, thus, target areas of potentially high risk. Environ Toxicol Chem 2014;33:447–452. © 2013 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial, and no modifications or adaptations are made.\u
Effects of silver nanoparticles (NM-300K) on Lumbricus rubellus earthworms and particle characterization in relevant test matrices including soil.

The impact of silver nanoparticles (AgNP; at 0 mg Ag/kg, 1.5 mg Ag/kg, 15.4 mg Ag/kg, and 154 mg Ag/kg soil) and silver nitrate (AgNO3 ; 15.4 mg Ag/kg soil) on earthworms, Lumbricus rubellus, was assessed. A 4-wk exposure to the highest AgNP treatment reduced growth and reproduction compared with the control. Silver nitrate (AgNO3 ) exposure also impaired reproduction, but not as much as the highest AgNP treatment. Long-term exposure to the highest AgNP treatment caused complete juvenile mortality. All AgNP treatments induced tissue pathology. Population modeling demonstrated reduced population growth rates for the AgNP and AgNO3 treatments, and no population growth at the highest AgNP treatment because of juvenile mortality. Analysis of AgNP treated soil samples revealed that single AgNP and AgNP clusters were present in the soil, and that the total Ag in soil porewater remained high throughout the long-term experiment. In addition, immune cells (coelomocytes) of earthworms showed sensitivity to both AgNP and AgNO3 in vitro. Overall, the present study indicates that AgNP exposure may affect earthworm populations and that the exposure may be prolonged because of the release of a dissolved Ag fraction to soil porewater
The importance of experimental time when assessing the effect of temperature on toxicity in poikilotherms

Temperature is an important factor affecting toxicity, determining chemical toxicokinetics and toxicodynamics in poikilothermic organisms. As also metabolic rates are affected by temperature, interactions between the emergence of toxic effects and time are very likely. The aim of this study was to investigate how temperature affected the toxicity of copper towards the nematode Caenorhabditis elegans when measured during short fixed timeframes compared to during full life-cycles. Copper toxicity was tested in two experiments at four or six temperatures in the range of 11 to 24°C, with copper concentrations spanning from one to 40 mg Cu/L agar, respectively. Reproduction and mortality were determined across the entire life-cycle, and the time to production of first egg and the population growth rate were calculated. The results showed that the 50% effect concentrations (EC50) of copper increased 1.5 to 2.5-fold with increasing temperature within the tested range, depending on endpoint. When calculating EC50 on reproduction after 24 or 96 hours, as is the typical setup for temperature/chemical interaction studies, results ranged from no temperature effect to effects much larger than for the full life cycle. Studies of temperature effects on toxicity must therefore be carefully designed in relation to the research question investigated
Hydraulic “Fracking”: Are surface water impacts an ecological concern?

Use of high‐volume hydraulic fracturing (HVHF) in unconventional reservoirs to recover previously inaccessible oil and natural gas is rapidly expanding in North America and elsewhere. Although hydraulic fracturing has been practiced for decades, the advent of more technologically advanced horizontal drilling coupled with improved slickwater chemical formulations has allowed extensive natural gas and oil deposits to be recovered from shale formations. Millions of liters of local groundwaters are utilized to generate extensive fracture networks within these low‐permeability reservoirs, allowing extraction of the trapped hydrocarbons. Although the technology is relatively standardized, the geographies and related policies and regulations guiding these operations vary markedly. Some ecosystems are more at risk from these operations than others because of either their sensitivities or the manner in which the HVHF operations are conducted. Generally, the closer geographical proximity of the susceptible ecosystem to a drilling site or a location of related industrial processes, the higher the risk of that ecosystem being impacted by the operation. The associated construction of roads, power grids, pipelines, well pads, and water‐extraction systems along with increased truck traffic are common to virtually all HVHF operations. These operations may result in increased erosion and sedimentation, increased risk to aquatic ecosystems from chemical spills or runoff, habitat fragmentation, loss of stream riparian zones, altered biogeochemical cycling, and reduction of available surface and hyporheic water volumes because of withdrawal‐induced lowering of local groundwater levels. The potential risks to surface waters from HVHF operations are similar in many ways to those resulting from agriculture, silviculture, mining, and urban development. Indeed, groundwater extraction associated with agriculture is perhaps a larger concern in the long term in some regions. Understanding the ecological impacts of these anthropogenic activities provides useful information for evaluations of potential HVHF hazards. Geographic information system–based modeling combined with strategic site monitoring has provided insights into the relative importance of these and other ecoregion and land‐use factors in discerning potential HVHF impacts. Recent findings suggest that proper siting and operational controls along with strategic monitoring can reduce the potential for risks to aquatic ecosystems. Nevertheless, inadequate data exist to predict ecological risk at this time. The authors suggest considering the plausibility of surface water hazards associated with the various HVHF operations in terms of the ecological context and in the context of relevant anthropogenic activities.  Environ Toxicol Chem 2014;33:1679–1689 . © 2014 SETA
PAHs, nitro‐PAHs, hopanes, and steranes in lake trout from Lake Michigan

The present study examines concentrations and risks of polycyclic aromatic hydrocarbons (PAHs), nitro‐PAHs (NPAHs), steranes, and hopanes in lake trout collected in Lake Michigan. A total of 74 fish were collected in 2 seasons at 3 offshore sites. The total PAH concentration (Σ 9 PAH) in whole fish ranged from 223 pg/g to 1704 pg/g wet weight, and PAH concentrations and profiles were similar across season, site, and sex. The total NPAH (Σ 9 NPAH) concentrations ranged from 0.2 pg/g to 31 pg/g wet weight, and carcinogenic compounds, including 1‐nitropyrene and 6‐nitrochrysene, were detected. In the fall, NPAH concentrations were low at the Illinois site (0.2–0.5 pg/g wet wt), and site profiles differed considerably; in the spring, concentrations and profiles were similar across sites, possibly reflecting changes in fish behavior. In the fall, the total sterane (Σ 5 Sterane) and total hopane (Σ 2 Hopane) levels reached 808 pg/g and 141 pg/g wet weight, respectively, but concentrations in the spring were 10 times lower. Concentrations in eggs (fall only) were on the same order of magnitude as those in whole fish. These results demonstrate the presence of target semivolatile organic compounds in a top predator fish, and are consistent with PAH biodilution observed previously. Using the available toxicity information for PAHs and NPAHs, the expected cancer risk from consumption of lake trout sampled are low. However, NPAHs contributed a significant portion of the toxic equivalencies in some samples. The present study provides the first measurements of NPAHs in freshwater fish, and results suggest that additional assessment is warranted.  Environ Toxicol Chem 2014;33:1792–1801 . © 2014 SETA
The use of assemblage models to describe trace element partitioning, speciation, and fate: a review

The fate of trace elements in soils, sediments and surface waters is largely determined by their binding to reactive components of which organic matter, metal oxides and clays are considered most important. Assemblage models, combining separate mechanistic complexation models for each of the reactive components, can be used to predict the solid-solution partitioning and speciation of trace elements in natural environments. In this review we provide a short overview of advanced ion binding models for organic matter and oxides and their application to artificial and natural assemblages. Modeling of artificial assemblages of mineral components and organic matter indicate that the interactions between organic and mineral components are important for trace element binding, particularly for oxyanions. The modelling of solid-solution partitioning in natural systems is generally adequate for metal cations, but less so for oxyanions, probably due to the neglect of organic matteroxide interactions in most assemblage models. The characterization of natural assemblages in terms of their components (active organic matter, reactive oxide surface) is key to successful model applications. Improved methods for characterization of reactive components in situ will enhance the applicability of assemblage models. Collection of compositional data for soil and water archetypes, or the development of relationships to estimate compositions from geospatially-available data, will further facilitate assemblage model use for predictive purposes
Testing WHAM-FTOX with laboratory toxicity data for mixtures of metals (Cu, Zn, Cd, Ag, Pb)

The WHAM-FTOX model describes cation toxicity to aquatic organisms in terms of (a) accumulation by the organism of metabolically-active protons and metals at reversible binding sites, and (b) differing toxic potencies of the bound cations. Cation accumulation (νi in mol g-1) is estimated through calculations with the WHAM chemical speciation model by assuming that organism binding sites can be represented by those of humic acid. Toxicity coefficients (αi) are combined with νi to obtain the variable FTOX ( = ∑ αiνi) which, between lower and upper thresholds (FTOX,LT, FTOX,UT), is linearly related to toxic effect. Values of αi, FTOX,LT and FTOX,LT are obtained by fitting toxicity data. Reasonable fits (72% of variance in toxic effect explained overall) were obtained for four large metal mixture acute toxicity experiments involving daphnids (Cu, Zn, Cd), lettuce (Cu, Zn, Ag) and trout (Zn, Cd, Pb). Strong non-additive effects, most apparent in results for tests involving Cd, could be explained approximately by purely chemical competition for metal accumulation. Tentative interpretation of parameter values obtained from these and other experimental data suggests the following order of bound cation toxicity: H < Al < (Cu Zn Pb UO2) < (Cd Ag). Another trend is a strong increase in Cd toxicity relative to that of Zn, as organism complexity increases (from bacteria to fish)