Concentrations Of Chemicals In Water Research Articles

Experimental investigation and comparative environmental impact analysis of conventional and naturally occurring kinetic hydrate inhibitors in offshore environments using toxicity and bioconcentration tools

In this present study, an in vivo experiment was carried out to determine the tendencies of a naturally occurring high-phenolic compound red-onion skin extract (HPC-ROSE) and conventional N-Vinylcaprolactam (N-VCAP) kinetic hydrate inhibitors (KHIs) to bio-accumulate in offshore environment through the analysis of their uptake and depuration kinetics by a Fish-Chemical Model using Cyprinus carpio marine invertebrate. This test was performed in the laboratory in a flow through experimental set up according to the guidelines by [49] (Fish-chemical exposure test). The uptake duration was 10 days with a depuration period of twenty days. The inhibitor toxicity test was evaluated by determining the 50 % lethal concentration (LC50) as highlighted by OSPAR Commission protocols. The solubility of the inhibitors was determined by a column elution technique. Similarly, a proton-enabled nuclear magnetic resonance (1HNMR) technique was used to measure the partitioning characteristics of the inhibitors in an immiscible mixture of octanol and water (Kow) by 1HNMR spectroscopy using a benchtop low-field NMR spectrometer. OSPAR Commission and ASTM standard protocols were used for the laboratory investigation of the static sediment toxicity tests. A reference chemical substance of known BCF and solubility (Ethyl Acetate, EtOAc) was used as control to check the experimental progression. The stock solution was prepared by solid phase desorption mechanisms. The HPC-ROSE does not constitute environmentally significant risk to aquatic life owing to its lower BCF values between 215 L/kg - 251.5L/Kg, Log-Kow of 1.2 and higher lethal concentration of 25140 mg/L. Unlike the NVCAP which is very toxic with lower lethal concentration of 1280 mg/L and higher BCF values in the range of 442.5L/Kg to 485 L/kg with Log-Kow of 1.5. Furthermore, Nuclear magnetic resonance (1HNMR) is a simple and reliable method of estimating partition coefficient characteristics (Kow) because the obtained Log-Kow values showed good agreements with that of shake flask and high-performance liquid chromatography techniques. Also, the chemical concentration in water has an inverse relationship with uptake rate constant (K1) and steady-state bioconcentration factor (BCFss). Finally, the theoretically estimated BCFs were higher than the steady-state (BCFss) values that were obtained from laboratory experiments for the different inhibitor samples and at all concentrations. This is due to the route by which Log-Kow was estimated since most of the empirical models are usually one-factor model consisting of partition coefficient and BCF.

The Influence Of Rock Mineralogy On Groundwater In The Kampungbaru Formation,Coal Mining Area, Anggana And Surrounding Area, District. Kutai Kartanegara

Coal mining activities using the open pit mining system method will have impacts, both positive and negative impacts, positive impacts will cause changes in improving socio-economic life, while negative impacts will affect changes in hydrogeological conditions and environmental changes such as increasing soil/rock acidity so that it will cause water contaminated. This condition has an impact on decreasing the quality and quantity of groundwater as a source of clean water. The purpose of this study was to determine the hydrogeological conditions around the study site, and the influence of rock mineralogy as a potential source of groundwater contamination, especially in the Kampungbaru Formation. The methods used to obtain data such as; pumping test, rock mineralogy analysis (knowing the characteristics) by conducting studies; petrography, microscopic analysis of ore, XRD analysis, XRF analysis and analysis of the potential of acid mine water, while knowing the chemical characterization of water by analyzing the concentration of anion cations, and classifying water classes. Knowing the characterization of rock mineralogy and water chemistry, the level/value of potential groundwater contamination in the study area will be known. The hope of this research is to know and understand the characteristics of mineralogy of rocks and groundwater chemistry, as well as hydrogeological conditions in Kampungbaru Formation, so that groundwater contamination can be known. Specific benefits of the research, which is to explore more detail hydrogeology of the mine and surrounding areas, to understand the characteristics of rock mineralogy and the characteristics of groundwater chemistry, and to know the source of groundwater contamination of the research area. Practical benefits can provide information to the public and government about the potential of good quality groundwater around the research area and know the groundwater location of good quality. The results of hydrogeological studies, study of mineralogy characterization and groundwater chemistry will be obtained conclusion such as: 1) Characteristics of aquifer in Kampungbaru Formation included in the category of productive aquifers. 2) Mineralogy of rocks affect the chemical concentration .. 3) Kampungbaru Formation has the content of metal mineral elements and water chemical concentrations that contain many sulphide compounds as acid mine formers. Stratigraphy of the study area is included in the Kampungbaru Formation and is part of the Kutai Basin (Kutai Basin). Lithology The Kampungbaru Formation consists of a rocky outcrop with sandstone with coal insertions and sandstone units.
 
 Keywords: Hydrogeology, characteristics of mineralogy and groundwater chemistry, contamination

Characterizing surface water concentrations of hundreds of organic chemicals in United States for environmental risk prioritization.

Thousands of chemicals are observed in freshwater, typically at trace levels. Measurements are collected for different purposes, so sample characteristics vary. Due to inconsistent data availability for exposure and hazard, it is complex to prioritize which chemicals may pose risks. We evaluated the influence of data curation and statistical practices aggregating surface water measurements of organic chemicals into exposure distributions intended for prioritizing based on nation-scale potential risk. The Water Quality Portal includes millions of observations describing over 1700 chemicals in 93% of hydrologic subbasins across the United States. After filtering to maintain quality and applicability while including all possible samples, we compared concentrations across sample types. We evaluated statistical methods to estimate per-chemical distributions for chosen samples. Overlaps between resulting exposure ranges and distributions representing no-effect concentrations for multiple freshwater species were used to rank estimated chemical risks for further assessment. When we apply explicit data quality and statistical assumptions, we find that there are 186 organic chemicals for which we can make screening-level estimates of surface water chemical concentration. Of the original 1700 observed chemicals, this number decreased primarily due to a predominance of censored values (that is, observations indicating concentrations too low to be measured). We further identify 423 chemicals where all measurements were censored but, through consideration of detection limits, risk might still be prioritized based on the detection limits themselves. In the final set of 1.5 million samples, the median environmental concentration of one chemical (acetic acid) exceeded the 5th percentile of no-effect concentrations for the most delicate freshwater species (the highest priority risk condition identified here), and a further 29 chemicals were identified for possible further evaluation based on a small margin between occurrence and toxicity values. This method shows the broad range of chemical concentrations seen for organic chemicals across the country and identifies methods of determining their central tendency, allowing for researchers to characterize higher-than-normal or lower-than-normal surface water conditions as well as providing an overall indication of the presence of organic chemicals in the United States. The highest chemical concentrations did not always indicate the highest-risk conditions. Even when accounting for the high level of uncertainty in these data due to differences in data collection and reporting across the set, some chemicals may still be categorized as higher environmental risk than others using this method, providing value to chemical safety decision makers and researchers by suggesting avenues for more focused investigation.

ENVIRONMENTAL IMPACTS OF HUMANITY’S CARELESSNESS PART II: INDUSTRIAL WASTES AND AQUATIC HAZARDS

It is a well-known fact that human beings are in the process of rapidly modernizing the world by utilizing various natural resources at an unprecedented speed. The accomplishment can initially be mistaken as human’s great achievement, but during the course of this swift development, we have been adding extra pressure on the envi-ronment, especially by disposing the harmful chemicals of industry. Secondly, we humans are also overly using the limited sources of nature, which is resulting in its depletion, eventually interrupting the natural cycle. Metals are the indispensable raw material for constructing infrastructures and for producing electronic products. However, extracting these metals from their corresponding ores can inflict serious consequences if no precautions are taken. Similarly, the everchanging fashion industry has exponentially raised the demand for cotton, which has eventually encouraged people to exploit the natural resources like water even more, resulting in climate change and even drying up of the whole sea in some cases. These activities also impose a formidable threat to the environment we live in and even can lead to the end of human existence. Due to human’s carelessness, the concentration of harmful chemicals in water, soil, and the air is already far higher than the permissible upper limit in many regions. These unacceptable higher levels of these harmful chemicals directly affect the health of not only human beings but all the living organisms living on the Earth. If the process is not curbed on time, we humans, with other wildlife and innocent organisms are bound to pay a hefty price.

Logistic Model of Population Toxicodynamics

The effect of pollutant in water on a population of aquatic organisms as a function of exposure time is studied. Natural assumptions are formulated regarding the character of this process, primarily, the linear relationship between the rate of decrease in the population, on the one hand, and the population size and the number of organisms killed by intoxication, on the other hand. The formulated assumptions are used to construct a model of population toxicodynamics, which describes the kinetics of suppression of the population by a logistic function. The results of model calculations are shown to agree with the available experimental data, thus justifying the formulated assumptions regarding the character of the intoxication process. An extension of the model is proposed through the incorporation of the dependence of the result of intoxication on pollutant concentration by the well-known Haber’s formula. The developed model was used to propose an equation of regulated toxicodynamics for organization of water use without violation of the regime of natural functioning of ecosystems. The obtained specification of the notions of the mechanisms of intoxication process is necessary for the substantiation of hygienic standards on the concentration of chemicals in water, forecasts of biodiversity, and the choice of measures for supporting weak components of trophic chains in aquatic ecosystems.

Optical Spectral Tools for Diagnosing Water Media Quality: A Case Study on the Angara/Yenisey River System in the Siberian Region

This paper presents the results of spectral optical measurements of hydrochemical characteristics in the Angara/Yenisei river system (AYRS) extending from Lake Baikal to the estuary of the Yenisei River. For the first time, such large-scale observations were made as part of a joint American-Russian expedition in July and August of 1995, when concentrations of radionuclides, heavy metals, and oil hydrocarbons were assessed. The results of this study were obtained as part of the Russian hydrochemical expedition in July and August, 2019. For in situ measurements and sampling at 14 sampling sites, three optical spectral instruments and appropriate software were used, including big data processing algorithms and an AYRS simulation model. The results show that the water quality in AYRS has improved slightly due to the reasonably reduced anthropogenic industrial impact. Chemical concentrations in water have been found to vary along the Angara River depending on the location of the dams. The results of in situ measurements and modeling evaluations are given. To overcome the uncertainties in the data caused by the large monitoring area, it is recommended to use the combined AYRS simulation model and the universal 8-channel spectrophotometer installed on a fixed platform for continuous monitoring.

Consequences of a Severe Drought on Dissolved Carbon Forms of a Tropical Mesoscale River Under High Human Influence

Extreme climatic events may be translated into a higher frequency of both dry and wet years. Frequent droughts pose a challenge to water supply in terms of both quantity and quality. In order to cope with this, there has to be a documentation on the concentration of chemicals in water during such events. The southeast region of Brazil experienced a major drought event in 2014 leading to number of social, economic, and environmental impacts. The objective of the present paper is to understand the effect of an extreme drought on dissolved organic and inorganic carbon concentrations of the Piracicabal river, which is under high human pressure. Concentrations of both dissolved organic (DOC) and inorganic carbon (DIC) were monitored daily, for 30 days, during a dry month in 2014. DOC values found here were at least twice those observed in the river in non-extreme conditions. Rain events within this drought led to significant differences in discharge, DOC, and DIC. We built a dilution-concentration model which described an exponential relationship between discharge and both carbon forms. This indicated that drastic changes in concentrations of DOC and DIC are expected during such events. Our results may also apply to a number of regions in the world especially those of the developing countries where rivers are highly subjected to sewage impact.

Long‐Term Trends in Acid Precipitation and Watershed Elemental Export From an Alpine Catchment of the Colorado Rocky Mountains, USA

AbstractAcid deposition associated with precipitation is an ecological problem that has affected watersheds in industrialized parts of North America and Europe, but remote landscapes, such as the Colorado Rocky Mountains, have also been impacted. The deposition of strong acids, including nitric and sulfuric acids, has decreased substantially over the past 30 years at Niwot Ridge, a high‐alpine watershed of Colorado. The pH of precipitation has followed these declines and has increased to ~5.5. Meanwhile, NH4+, another important constituent of acid/base balance, and a fertilizing nutrient, has more than doubled in precipitation between 1984 and 2017. A statistical model of long‐term water chemistry concentrations and loads revealed a variety of trends in watershed export of acids and bases, some of which were unexpected, and remain unexplained. For example, despite declining sulfate deposition, sulfate export has increased. On the other hand, watershed nitrate export has remained constant despite decreases in atmospheric deposition, while watershed NH4+ export has increased, albeit minimally, relative to total nitrogen export. Watershed pH and alkalinity appear to have stabilized in response to decreased acid precipitation, which may be explained by geochemical processes, such as carbonate weathering. Overall, in this high‐alpine watershed, atmospheric deposition is trending toward preindustrial conditions, and there is a need to conduct targeted, process‐based studies to determine the mechanisms underlying these trends. The unexpected watershed responses that we identify here require a new framework for understanding acid precipitation recovery.

Groundwater discharges as a source of phytoestrogens and other agriculturally derived contaminants to streams

Groundwater discharge zones in streams are important habitats for aquatic organisms. The use of discharge zones for thermal refuge and spawning by fish and other biota renders them susceptible to potential focused discharge of groundwater contamination. Currently, there is a paucity of information about discharge zones as a potential exposure pathway of chemicals to stream ecosystems. Using thermal mapping technologies to locate groundwater discharges, shallow groundwater and surface water from three rivers in the Chesapeake Bay Watershed, USA were analyzed for phytoestrogens, pesticides and their degradates, steroid hormones, sterols and bisphenol A. A Bayesian censored regression model was used to compare groundwater and surface water chemical concentrations. The most frequently detected chemicals in both ground and surface water were the phytoestrogens genistein (79%) and formononetin (55%), the herbicides metolachlor (50%) and atrazine (74%), and the sterol cholesterol (88%). There was evidence suggesting groundwater discharge zones could be a unique exposure pathway of chemicals to surface water systems, in our case, metolachlor sulfonic acid (posterior mean concentration = 150 ng/L in groundwater and 4.6 ng/L in surface water). Our study also demonstrated heterogeneity of chemical concentration in groundwater discharge zones within a stream for the phytoestrogen formononetin, the herbicides metolachlor and atrazine, and cholesterol. Results support the hypothesis that discharge zones are an important source of exposure of phytoestrogens and herbicides to aquatic organisms. To manage critical resources within the Chesapeake Bay Watershed, more work is needed to characterize exposure in discharge zones more broadly across time and space.

Graphene-filter-mounted tin-oxide-nanowire-transistor for chemical sensor

When attempting to measure the chemical concentration in water using a semiconductor sensor, an abnormal current change occurs when the semiconductor channel is directly exposed to the water containing the chemical substance. To accurately measure the concentration of the chemical substances in the water, it is necessary to cover the semiconductor channel region with a selective filter that allows the chemical vapor to pass through but not the chemical solution and water. In this study, we investigated a method for detecting chemical substances present in water, using a tin oxide (SnO2) nanowire transistor incorporated with a three-dimensional (3D)-graphene-based selective filter with (heptadecafluoro-1,1,2,2-tetrahydrodecyl)trichlorosilane (HDF-S), which selectively allowed the chemical vapor to pass through, but blocked the liquid chemical and water. When the chemical vapors, such as nitric acid, toluene, and benzene, in water penetrated the 3D-graphene-based selective filter with HDF-S and contacted the SnO2 nanowire channel, the conductivity of the SnO2 nanowire transistor changed according to the chemical concentration. Thus, the SnO2 nanowire transistor used as a chemical sensor was immersed in water containing chemical substances, to determine the chemical concentration accurately.

THE PROBLEM OF HYGIENIC REGULATION OF ARSENIC IN DRINKING WATER IN CONTEXT OF HARMONIZATION WITH INTERNATIONAL REQUIREMENTS

The article presents the analysis of modern data and the history of the development of normative documents regulating the content of arsenic in drinking water in Russia and other countries. The comparative characteristic of arsenic rationing in drinking water on a global scale and in the context of individual countries is given. The absence of uniform requirements for arsenic content in drinking water in the current regulatory documents of Russia is noted. In terms of harmonization of the regulatory framework with international requirements, it is recommended to bring SanPin 2.1.4.1074-01 «Drinking water. Hygienic requirements for the quality of water of centralized systems of drinking water supply. Quality control.» to GN 2.1.5.1315-03 «Maximum permissible concentration of chemicals in water of water facilities used for commercial, household, and recreational purposes».

Mexican poppy (Argemone mexicana) control in cornfield using deep learning neural networks: a perspective

ABSTRACTMexican poppy (Argemone mexicana) is a widespread noxious annual weed associated with crops such as corn (Zea mays L.), and this weed is persistent because it produces a seed bank. This invasive weed species must be controlled even in the dry season because Mexican poppy has a deep-reaching root system, which taps water from deep soil layers. Cases of a human death caused by Mexican poppy seeds in South Africa, India, and other Eastern countries were reported from the early years of the twentieth century. However, when weeds are controlled uniformly instead of site-specific or precision farming method across the spatially variable fields, there are environmental pollution challenges. Site-specific weed control techniques have gained interest in the precision farming community over the last years mainly because of Global Positioning System (GPS) applications, and a controlled measure of herbicides are applied where there are weeds in the field, and areas with more clusters of weeds receive the correct amount of herbicide application. Mexican poppy has prickles and is a nuisance to farmers, and herbicides represent a severe health hazard to humans due to chemical concentrations in water. For that reason, we propose the design of a site-specific weed control plan to use a row-guided robot to detect and identify weeds with accuracy, control speed timeously, and spray herbicides with a high level of precision and automation. These robotics methods are reported to be environmentally conscious, and economically efficient with less labour and management. The proposed method of deep learning neural networks, which use row-guided robots, a machine is trained on multiple images to identify weeds automatically from the main crop, and release a controlled measure of herbicides based on weed location and density, and spray weeds on-the-go upon emergence.

Time-Integrative Passive sampling combined with TOxicity Profiling (TIPTOP): an effect-based strategy for cost-effective chemical water quality assessment

This study aimed at demonstrating that effect-based monitoring with passive sampling followed by toxicity profiling is more protective and cost-effective than the current chemical water quality assessment strategy consisting of compound-by-compound chemical analysis of selected substances in grab samples. Passive samplers were deployed in the Dutch river delta and in WWTP effluents. Their extracts were tested in a battery of bioassays and chemically analyzed to obtain toxicity and chemical profiles, respectively. Chemical concentrations in water were retrieved from publicly available databases. Seven different strategies were used to interpret the chemical and toxicity profiles in terms of ecological risk. They all indicated that the river sampling locations were relatively clean. Chemical-based monitoring resulted for many substances in measurements below detection limit and could only explain <20% of the observed in vitro toxicity. Effect-based monitoring yielded more informative conclusions as it allowed for ranking the sampling sites and for estimating a margin-of-exposure towards chronic effect ranges. Effect-based monitoring was also cheaper and more cost-effective (i.e. yielding more information per euro spent). Based on its identified strengths, weaknesses, opportunities, and threats (SWOT), a future strategy for effect-based monitoring has been proposed.

Otolith chemistry does not just reflect environmental conditions: A meta‐analytic evaluation

AbstractFish otoliths are widely used to answer biological and ecological questions related to movements and habitat use based on their chemical composition. Two fundamental assumptions underlie otoliths as environmental tracers and proxies for reconstructing exposure histories: (i) otolith chemistry reflects water chemistry, and (ii) ambient environmental conditions affect otolith element incorporation. Here, we test these assumptions for Sr and Ba through meta‐analyses. Our first meta‐analysis confirmed a correlation between concentrations of Sr:Ca and Ba:Ca in otoliths and the surrounding water, both elements displaying positive otolith–water correlations. The second meta‐analysis examined the relative influences of salinity and temperature on otolith Sr and Ba partition coefficients (an index of otolith element regulation). Our environmental effects meta‐analysis confirmed that otolith Sr and Ba are affected by temperature and salinity; however, study‐level covariates (e.g., water chemical concentrations and species ecological niche) influenced otolith element incorporation, and this varied by element. These findings confirm that even though otolith chemistry and elemental incorporation are differentially affected by environmental conditions, other factors play a decisive role. While we focused on studies that directly linked water and otolith chemistry, systematic reviews are key to further demonstrate the link between otolith chemistry and extrinsic and intrinsic factors. Ultimately, disentangling the relative effects of multiple factors on otolith chemistry and a detailed understanding of biomineralization is critical to the continued use of otoliths as natural tags for tracing fish movements and habitat use.

Tracking pesticide fate in conventional banana cultivation in Costa Rica: A disconnect between protecting ecosystems and consumer health

Conventional banana cultivation in Costa Rica relies on heavy pesticide use. While pesticide residues in exported bananas do not generally represent a safety concern for consumers abroad, ecosystem and human health in producing regions are not likewise protected. In Costa Rica, most studies on pesticide residues in the environment are snapshots, limiting our ability to identify temporal dynamics that can inform risk mitigation strategies. To help bridge this gap, we created a dynamic multimedia model for the Caño Azul River drainage area, which is heavily influenced by banana and pineapple plantations. This model estimates chemical concentrations in water, air, soil, sediments, and banana plants through time, based on pesticide properties and emission patterns and on variable environmental conditions. Case studies for three representative chemicals—the herbicide diuron, the nematicide ethoprofos, and the fungicide epoxiconazole—show that concentrations in fruit remain below EU and US maximum residue limits set to ensure consumer health, while those in the environment are highly variable, reaching peak concentrations in water that can exceed thresholds for ecosystem health. Critical research needs, including incorporating sediment dynamics and the effects of adjuvants on the properties and transport of active ingredients into multimedia models, were identified.

First report of a novel multiplexer pumping system coupled to a water quality probe to collect high temporal frequency in situ water chemistry measurements at multiple sites

The increasing availability and use of high-frequency water quality sensors has enabled unprecedented observations of temporal variability in water chemistry in aquatic ecosystems. However, we remain limited by the prohibitive costs of these probes to explore spatial variability in natural systems. To overcome this challenge, we have developed a novel auto-sampler system that sequentially pumps water from up to 12 different sites located within a 12 m radius to a single water quality probe. This system is able to generate high temporal frequency in situ water chemistry data from multiple replicated units during experiments as well as multiple sites and depths within natural aquatic ecosystems. Thus, with one water quality probe, we are able to observe rapid changes in water chemistry concentrations over time and space. Here, we describe the coupled multiplexer-probe system and its performance in two case studies: a mesocosm experiment examining the effects of water current velocity on nitrogen dynamics in constructed wetland sediment cores and a whole-ecosystem manipulation of redox conditions in a reservoir. In both lotic and lentic case studies, we observed minute-scale changes in nutrient concentrations, which provide new insight on the variability of biogeochemical processes. Moreover, in the reservoir, we were able to measure rapid changes in metal concentrations, in addition to those of nutrients, in response to changes in redox. Consequently, we believe that this coupled system holds great promise for measuring biogeochemical fluxes in a diverse suite of aquatic ecosystems and experiments.

Assessment of water quality in urban streams based on larvae of Hydropsyche angustipennis (Insecta, Trichoptera)

Hydropsyche angustipennis (Insecta, Trichoptera) larvae were used as indicators of stream contamination in the city of Łódź, Poland. The larvae of H. angustipennis were present at 9 sampling sites established for this study. Significant differences between the sampling sites were noted for environmental parameters as well as concentration of chemicals in water and biodiversity of aquatic invertebrates. Statistical analyses showed significant correlations between quantity and quality of water pollutants and density of H. angustipennis larvae, concentration of metals in larval bodies, and the appearance of morphological anomalies in tracheal gills and anal papillae. In comparison to literature data, the level of contaminants in water, including heavy metals, for each of the studied streams of Łódź was surprisingly low while concentration of these metals in the whole bodies of H. angustipennis larvae was very high. Some of the heavy metals present in the water might be identified only after conducting analyses of their concentration in the larval bodies. Therefore, long life cycle of H. angustipennis and heavy metal tolerance with a possibility of their accumulation in the larval bodies may constitute a support to traditional chemical assessment of water quality or traditional biomonitoring.

Reproductive health indicators of fishes from Pennsylvania watersheds: association with chemicals of emerging concern.

Fishes were collected at 16 sites within the three major river drainages (Delaware, Susquehanna, and Ohio) of Pennsylvania. Three species were evaluated for biomarkers of estrogenic/antiandrogenic exposure, including plasma vitellogenin and testicular oocytes in male fishes. Smallmouth bass Micropterus dolomieu, white sucker Catostomus commersonii, and redhorse sucker Moxostoma species were collected in the summer, a period of low flow and low reproductive activity. Smallmouth bass were the only species in which testicular oocytes were observed; however, measurable concentrations of plasma vitellogenin were found in male bass and white sucker. The percentage of male bass with testicular oocytes ranged from 10 to 100 %, with the highest prevalence and severity in bass collected in the Susquehanna drainage. The percentage of males with plasma vitellogenin ranged from 0 to 100 % in both bass and sucker. Biological findings were compared with chemical analyses of discrete water samples collected at the time of fish collections. Estrone concentrations correlated with testicular oocytes prevalence and severity and with the percentage of male bass with vitellogenin. No correlations were noted with the percentage of male sucker with vitellogenin and water chemical concentrations. The prevalence and severity of testicular oocytes in bass also correlated with the percent of agricultural land use in the watershed above a site. Two sites within the Susquehanna drainage and one in the Delaware were immediately downstream of wastewater treatment plants to compare results with upstream fish. The percentage of male bass with testicular oocytes was not consistently higher downstream; however, severity did tend to increase downstream.Electronic supplementary materialThe online version of this article (doi:10.1007/s10661-014-3868-5) contains supplementary material, which is available to authorized users.

An updated Quantitative Water Air Sediment Interaction (QWASI) model for evaluating chemical fate and input parameter sensitivities in aquatic systems: Application to D5 (decamethylcyclopentasiloxane) and PCB-180 in two lakes

The QWASI fugacity mass balance model has been widely used since 1983 for both scientific and regulatory purposes to estimate the concentrations of organic chemicals in water and sediment, given an assumed rate of chemical emission, advective inflow in water or deposition from the atmosphere. It has become apparent that an updated version is required, especially to incorporate improved methods of obtaining input parameters such as partition coefficients. Accordingly, the model has been revised and it is now available in spreadsheet format. Changes to the model are described and the new version is applied to two chemicals, D5 (decamethylcyclopentasiloxane) and PCB-180, in two lakes, Lake Pepin (MN, USA) and Lake Ontario, showing the model’s capability of illustrating both the chemical to chemical differences and lake to lake differences. Since there are now increased regulatory demands for rigorous sensitivity and uncertainty analyses, these aspects are discussed and two approaches are illustrated. It is concluded that the new QWASI water quality model can be of value for both evaluative and simulation purposes, thus providing a tool for obtaining an improved understanding of chemical mass balances in lakes, as a contribution to the assessment of fate and exposure and as a step towards the assessment of risk.

A Microfluidic Device for Continuous Sensing of Systemic Acute Toxicants in Drinking Water

A bioluminescent-cell-based microfluidic device for sensing toxicants in drinking water was designed and fabricated. The system employed Vibrio fischeri cells as broad-spectrum sensors to monitor potential systemic cell toxicants in water, such as heavy metal ions and phenol. Specifically, the chip was designed for continuous detection. The chip design included two counter-flow micromixers, a T-junction droplet generator and six spiral microchannels. The cell suspension and water sample were introduced into the micromixers and dispersed into droplets in the air flow. This guaranteed sufficient oxygen supply for the cell sensors. Copper (Cu2+), zinc (Zn2+), potassium dichromate and 3,5-dichlorophenol were selected as typical toxicants to validate the sensing system. Preliminary tests verified that the system was an effective screening tool for acute toxicants although it could not recognize or quantify specific toxicants. A distinct non-linear relationship was observed between the zinc ion concentration and the Relative Luminescence Units (RLU) obtained during testing. Thus, the concentration of simple toxic chemicals in water can be roughly estimated by this system. The proposed device shows great promise for an early warning system for water safety.