A novel mathematical template for developing fDOM probe fluorescence signal correction models for freshwaters.

The reliable application of field deployable fluorescent dissolved organic matter (fDOM) probes is hindered by several influencing factors which need to be compensated. This manuscript describes the corrections of temperature, pH, turbidity and inner filter effect on fluorescence signal of a commercial fDOM probe (fDOMs). For this, Australian waters with wide ranging qualities were selected, e.g. dissolved organic carbon (DOC) ranging from ∼1 to ∼30 mg/L, specific UV absorbance at 254 nm from ∼1 to ∼6 L/m/mg and turbidity from ∼1 to ∼ 350 FNU. Laboratory-based model calibration experiments (MCEs) were performed. A model template was developed and used for the development of the correction models. For each factor, data generated through MCEs were used to determine model coefficient (α) values by fitting the generated model to the experimental data. Four discrete factor models were generated by determination of a factor-specific α value. The α values derived for each water of the MCEs subset were consistent for each factor model. This indicated generic nature of the four α values across wide-ranging water qualities. High correlation between fDOMs and DOC were achieved after applying the four-factor compensation models to new data (r, 0.96, p < 0.05). Also, average biases (and %) between DOC predicted through fDOMs and actual DOC were decreased by applying the four-factor compensation model (from 3.54 (60.9%) to 1.28 (16.7%) mg/L DOC). These correction models were incorporated into a Microsoft EXCEL-based software termed EXOf-Correct for ready-to-use applications.

Occurrence and risks of pharmaceuticals, personal care products, and endocrine-disrupting compounds in Chinese surface waters.

The continuous and rapid increase of chemical pollution in surface waters has become a pressing and widely recognized global concern. As emerging contaminants (ECs) in surface waters, pharmaceutical and personal care products (PPCPs), and endocrine-disrupting compounds (EDCs) have attracted considerable attention due to their wide occurrence and potential threat to human health. Therefore, a comprehensive understanding of the occurrence and risks of ECs in Chinese surface waters is urgently required. This study summarizes and assesses the environmental occurrence concentrations and ecological risks of 42 pharmaceuticals, 15 personal care products (PCPs), and 20 EDCs frequently detected in Chinese surface waters. The ECs were primarily detected in China's densely populated and highly industrialized regions. Most detected PPCPs and EDCs had concentrations between ng/L to µg/L, whereas norfloxacin, caffeine, and erythromycin had relatively high contamination levels, even exceeding 2000 ng/L. Risk evaluation based on the risk quotient method revealed that 34 PPCPs and EDCs in Chinese surface waters did not pose a significant risk, whereas 4-nonylphenol, 4-tert-octylphenol, 17α-ethinyl estradiol, 17ß-estradiol, and triclocarban did. This review provides a comprehensive summary of the occurrence and associated hazards of typical PPCPs and EDCs in Chinese surface waters over the past decade, and will aid in the regulation and control of these ECs in Chinese surface waters.

A one health approach for monitoring antimicrobial resistance: developing a national freshwater pilot effort.

Antimicrobial resistance (AMR) is a world-wide public health threat that is projected to lead to 10 million annual deaths globally by 2050. The AMR public health issue has led to the development of action plans to combat AMR, including improved antimicrobial stewardship, development of new antimicrobials, and advanced monitoring. The National Antimicrobial Resistance Monitoring System (NARMS) led by the United States (U.S) Food and Drug Administration along with the U.S. Centers for Disease Control and U.S. Department of Agriculture has monitored antimicrobial resistant bacteria in retail meats, humans, and food animals since the mid 1990's. NARMS is currently exploring an integrated One Health monitoring model recognizing that human, animal, plant, and environmental systems are linked to public health. Since 2020, the U.S. Environmental Protection Agency has led an interagency NARMS environmental working group (EWG) to implement a surface water AMR monitoring program (SWAM) at watershed and national scales. The NARMS EWG divided the development of the environmental monitoring effort into five areas: (i) defining objectives and questions, (ii) designing study/sampling design, (iii) selecting AMR indicators, (iv) establishing analytical methods, and (v) developing data management/analytics/metadata plans. For each of these areas, the consensus among the scientific community and literature was reviewed and carefully considered prior to the development of this environmental monitoring program. The data produced from the SWAM effort will help develop robust surface water monitoring programs with the goal of assessing public health risks associated with AMR pathogens in surface water (e.g., recreational water exposures), provide a comprehensive picture of how resistant strains are related spatially and temporally within a watershed, and help assess how anthropogenic drivers and intervention strategies impact the transmission of AMR within human, animal, and environmental systems.

Pollutant Photodegradation Affected by Evaporative Water Concentration in a Climate Change Scenario.

Evaporative water concentration takes place in arid or semi-arid environments when stationary water bodies, such as lakes or ponds, prevalently lose water by evaporation, which prevails over outflow or seepage into aquifers. Absence or near-absence of precipitation and elevated temperatures are important prerequisites for the process, which has the potential to deeply affect the photochemical attenuation of pollutants, including contaminants of emerging concern (CECs). Here we show that water evaporation would enhance the phototransformation of many CECs, especially those undergoing degradation mainly through direct photolysis and triplet-sensitized reactions. In contrast, processes induced by hydroxyl and carbonate radicals would be inhibited. Our model results suggest that the photochemical impact of water evaporation might increase in the future in several regions of the world, with no continent likely being unaffected, due to the effects of local precipitation decrease combined with an increase in temperature that facilitates evaporation.

Toxicity threshold and ecological risk of nitrate in rivers based on endocrine-disrupting effects: A case study in the Luan River basin, China.

Nitrate, as a crucial nutrient, is consistently targeted for controlling water eutrophication globally. However, there is considerable evidence suggesting that nitrate has endocrine-disrupting potential on aquatic organisms. In this study, the sensitivity of various adverse effects to nitrate nitrogen (nitrate-N) was compared, and a toxicity threshold based on endocrine-disrupting effects was derived. The spatiotemporal variations of nitrate-N concentrations in the Luan River basin were investigated, and the associated aquatic ecological risks were evaluated using a comprehensive approach. The results showed that reproduction and development were the most sensitive endpoints to nitrate, and their distribution exhibited significant differences compared to behavior. The derived threshold based on endocrine-disrupting effects was 0.65 mgL-1, providing adequate protection for the aquatic ecosystem. In the Luan River basin, the mean nitrate-N concentrations during winter (4.4 mgL-1) were significantly higher than those observed in spring (0.7 mgL-1) and summer (1.2 mgL-1). Tributary inputs had an important influence on the spatial characteristics of nitrate-N in the mainstream, primarily due to agricultural and population-related contamination. The risk quotients (RQ) during winter, summer, and spring were evaluated as 6.7, 1.8, and 1.1, respectively, and the frequency of exposure concentrations exceeding the threshold was 100 %, 64.3 %, and 42.5 %, respectively. At the ecosystem level, nitrate posed intermediate risks to aquatic organisms during winter and summer in the Luan River basin and at the national scale in China. We suggest that nitrate pollution control should not solely focus on water eutrophication but also consider the endocrine disruptive effect on aquatic animals.

Toxicity of water-soluble polymers polyethylene glycol and polyvinyl alcohol for fish and frog embryos.

Personal Care Products (PCPs) have been one of the most studied chemicals in the last twenty years since they were identified as pseudo-persistent pollutants by the European Union in the early 2000s. The accumulation of PCPs in the aquatic environment and their effects on non-target species make it necessary to find new, less harmful, substances. Polyethylene glycol (PEGs) and polyvinyl alcohol (PVAs) are two polymers that have increased their presence in the composition of PCPs in recent years, but little is known about the effect of their accumulation in the environment on non-target species. Through embryotoxicity tests on two common models of aquatic organisms (Danio rerio and Xenopus laevis), this work aims to increase the knowledge of PEGs and PVAs' effects on non-target species. Animals were exposed to the pollutant for 96 h. The main embryotoxicity endpoint (mortality, hatching, malformations, heartbeat rate) was recorded every 24 h. The most significant results were hatching delay in Danio rerio exposed to both chemicals, in malformations (oedema, body malformations, changes in pigmentation and deformations of spine and tail) in D. rerio and X. laevis and significant change in the heartbeat rate (decrease or increase in the rate) in both animals for all chemicals tested.

Assessing glyphosate and AMPA pesticides in the Ofanto River waters and sediments.

In the present study, we determined glyphosate (GPS) and aminomethylphosphonic acid (AMPA) in the water and sediments of the Ofanto River (Italy), evaluating their transport from the mouth to the sea. Sediments were collected twice in 2021 during low and high tide; waters were sampled on a seasonal basis. The results showed the prevalence of GPS and AMPA in the water with concentrations equal to 190 and 3053 ng/l, respectively. We also found GPS and AMPA in the sediments with values of 0.95 and 11.34 ng/g. In water, pesticides were detected in all seasons with peaks in concentrations during summer and spring. A significant positive correlation between the pesticides in the sediments and the water pH and a negative correlation with salinity was observed. An estimation of the average loads revealed a discharge of 64.11 kg/yr. of GPS and 958.37 kg/yr. of AMPA from the river to the marine environment.

Ecotoxicological evaluation of surface waters in Northern Namibia.

The increasing pressure on freshwater systems due to intensive anthropogenic use is a big challenge in central-northern Namibia and its catchment areas, the Kunene and the Kavango Rivers, and the Cuvelai-Etosha Basin, that provide water for more than 1 million people. So far, there is no comprehensive knowledge about the ecological status and only few knowledge about the water quality. Therefore, it is crucial to learn about the state of the ecosystem and the ecological effects of pollutants to ensure the safe use of these resources. The surface waters of the three systems were sampled, and three bioassays were applied on three trophic levels: algae, daphnia, and zebrafish embryos. Additionally, in vitro assays were performed to analyze mutagenicity (Ames fluctuation), dioxin-like potential (micro-EROD), and estrogenicity (YES) by mechanism-specific effects. The results show that acute toxicity to fish embryos and daphnia has mainly been detected at all sites in the three catchment areas. The systems differ significantly from each other, with the sites in the Iishana system showing the highest acute toxicity. At the cellular level, only weak effects were identified, although these were stronger in the Iishana system than in the two perennial systems. Algae growth was not inhibited, and no cytotoxic effects could be detected in any of the samples. Mutagenic effects and an estrogenic potential were detected at three sites in the Iishana system. These findings are critical in water resource management as the effects can adversely impact the health of aquatic ecosystems and the organisms within them.

Occurrence, ecotoxicity and ecological risks of psychoactive substances in surface waters.

Psychoactive substances (PSs) represent a subset of emerging contaminants. Their widespread production and utilization contribute to a growing ecological burden and risk on a global scale. Conventional wastewater treatment methods have proven insufficient in adequately removing psychoactive substances, leading to their occurrence in surface water ecosystems worldwide. As of present, however, a thorough understanding of their geographical prevalence and distribution patterns remains elusive. Further, in the existing literature, there is a scarcity of comprehensive overviews that systematically summarize the toxicity of various psychoactive substances towards aquatic organisms. Through summarizing almost 140 articles, the present study provides an overview of the sources, pollution status, and biotoxicity of psychoactive substances in surface waters, as well as an assessment of their ecological risks. Concentrations of several psychoactive substances in surface waters were found to be as high as hundreds or even thousands of ng·L-1. In parallel, accumulation of psychoactive substances in the tissues or organs of aquatic organisms was found to potentially cause certain adverse effects, including behavioral disorders, organ damage, and DNA changes. Oxidative stress was found to be a significant factor in the toxic effects of psychoactive substances on organisms. The application of the risk quotient approach indicated that psychoactive substances posed a medium to high risk in certain surface water bodies, as well as the need for sustained long-term attention and management strategies.

Browning from headwaters to coastal areas in the boreal region: Trends and drivers.

Browning of freshwaters, mainly caused by increased terrestrial organic carbon loading, has been widely studied during the last decades. However, there are still uncertainties regarding both the extent of browning in different aquatic ecosystems and the actual importance of different driving forces and mechanisms. To refine understanding of the extent and causes of browning and its temporal variation, we gathered a comprehensive dataset including 746 Finnish water quality monitoring stations representing various waterbody types: streams, rivers, lakes, and coastal waters. Monotonic trend analyses revealed that TOC concentrations increased in all waterbody types during the study period from 1990 to 2020, whereas non-linear trends indicated that upward trends in TOC concentrations have substantially decreased since the mid-2000s. However, despite the upward trends levelling off, non-linear analyses also indicated decreases in TOC concentrations at only a few stations. As a result, the TOC contents of the majority of Finnish waterbody types in 2020 were at a higher level than in 1990. To examine the driving forces of increasing TOC concentrations, we selected 100 riverine catchments and linked the detected trends to 24 different drivers, including both hydrometeorological and catchment characteristics. The increased TOC concentrations in surface waters could be connected to diverse human impacts: hydrometeorological variables impacted by climate change, decreased acidic deposition, and land use in terms of peatland drainage. The importance of increased temperatures was emphasized, and its role as a driver of increased leaching of organic carbon in the forthcoming years is expected to grow with climate change.

Monthly variability of floating plastic contamination in Lake Maggiore (Northern Italy).

The monitoring of plastics in freshwater ecosystems has witnessed a significant increase in recent years, driven by the awareness that approximately 80 % of marine plastic litter originates from terrestrial sources transported to the seas through lakes and rivers. Consequently, it is imperative to develop monitoring plans that offer a comprehensive understanding of plastic contamination in these aquatic environments, given their seasonal variations in hydrochemical characteristics and anthropogenic sources. Historically, most global lake monitoring campaigns have been limited to one-time or, at most, seasonal sampling. In this context, the primary objective of the present study was to assess the quantitative and qualitative monthly variations of floating plastics in Lake Maggiore, a large European lake with high ecological and economic significance. Twelve transverse transects were conducted from January to December 2022 using a Manta-net with a 100 µm mesh. Characterization of each plastic particle was performed using a µ-Fourier Transform Infrared Spectroscope (µFT-IR). The results revealed relatively low levels of contamination in Lake Maggiore when compared with other lakes worldwide exclusively from a secondary origin. However, a considerable heterogeneity was observed, both quantitatively and qualitatively. Notably, we identified a 13-fold difference between the minimum (0.02 plastics/m3 in September) and maximum (0.29 plastics/m3 in December) concentrations of plastics, accompanied by significant variations in polymer composition. Our monitoring underscored the necessity of also considering the temporal variation as a potential factor influencing plastic contamination in a lake. Moreover, frequent sampling emerged as a crucial requirement to accurately gauge the extent of plastic pollution, yielding robust and valuable data essential for effective environmental management.

Ionic Liquid Modified Polymer Gel for Arsenic Speciation.

A new ionic liquid modified polymer gel containing methylimidazolium groups (poly(MIA)) is proposed as a sorbent for the separation and enrichment of trace inorganic and organic arsenic species in surface waters. The poly(MIA) was synthesized by chemical modification of polymeric precursor using post-polymerization modification of poly(glycidyl methacrylate-co-trimethylolpropane trimethacrylate). The composition, structure, morphology, and surface properties of the prepared particles were characterized using elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption-desorption measurements. Optimization experiments showed that at pH 8, monomethylarsonic acid (MMAs), dimethylarsinic acid (DMAs), and As(V) were completely retained on the poly(MIA), while the sorption of As(III) was insignificant. The desorption experiments revealed that due to the weaker binding of organic arsenic species, selective elution with 1 mol/L acetic acid for MMAs + DMAs, followed by elution with 2 mol/L hydrochloric acid for As(V), ensured their quantitative separation. The adsorption kinetic and mechanism were defined. The analytical procedure for As(III), As(V), MMAs, and DMAs determination in surface waters was developed and validated through the analysis of certified reference material.

Intelligent classification and pollution characteristics analysis of microplastics in urban surface waters using YNet.

Microplastics (MPs, ≤ 5 mm in size) are hazardous contaminants that pose threats to ecosystems and human health. YNet was developed to analyze MPs abundance and shape to gain insights into MPs pollution characteristics in urban surface waters. The study found that YNet achieved an accurate identification and intelligent classification performance, with a dice similarity coefficient (DSC) of 90.78%, precision of 94.17%, and recall of 89.14%. Analysis of initial MPs levels in wetlands and reservoirs revealed 127.3 items/L and 56.0 items/L. Additionally, the MPs in effluents were 27.0 items/L and 26.3 items/L, indicating the ability of wetlands and reservoirs to retain MPs. The concentration of MPs in the lower reaches of the river was higher (45.6 items/L) compared to the upper reaches (22.0 items/L). The majority of MPs detected in this study were fragments, accounting for 51.63%, 54.94%, and 74.74% in the river, wetland, and reservoir. Conversely, granules accounted for the smallest proportion of MPs in the river, wetland, and reservoir, representing only 11.43%, 10.38%, and 6.5%. The study proves that the trained YNet accurately identify and intelligently classify MPs. This tool is essential in comprehending the distribution of MPs in urban surface waters and researching their sources and fate.

Surface-Water Nitrate Exposure to World Populations Has Expanded and Intensified during 1970-2010.

Excessive nitrate in surface waters deteriorates the water quality and threatens human health. Human activities have caused increased nitrate concentrations in global surface waters over the past 50 years. An assessment of the long-term trajectory of surface-water nitrate exposure to world populations and the associated potential health risks is imperative but lacking. Here, we used global spatially explicit data on surface-water nitrate concentrations and population density, in combination with thresholds for health risks from epidemiological studies, to quantify the long-term changes in surface-water nitrate exposure to world populations at multiple spatial scales. During 1970-2010, global populations potentially affected by acute health risks associated with surface-water nitrate exposure increased from 6 to 60 million persons per year, while populations at potential chronic health risks increased from 169 to 1361 million persons per year. Potential acute risks have increasingly affected Asian countries. Populations potentially affected by chronic risks shifted from dominance by high-income countries (in Europe and North America) to middle-income countries (in Asia and Africa). To mitigate adverse health effects associated with surface-water nitrate exposure, anthropogenic nitrogen inputs to natural environments should be drastically reduced. International and national standards of maximum nitrate contamination may need to be lowered.

Case Study of Diesters of o-Phthalic Acid in Surface Waters with Background Levels of Pollution.

Lake Baikal was studied as a model for elucidating the general pattern of o-phthalic acid diester (PAE) distributions in surface waters with background pollution levels. The influence of factors including congeners, concentrations, sampling points, seasons, years, and potential sources was considered and the environmental risk for various hydrobionts was established. Priority PAEs in Baikal waters are represented by dimethyl phthalate (DMP), diethyl phthalates (DEP), di-n-butyl phthalate (DnBP) and di-(2-ethylhexyl)phthalate (DEHP). Statistically valuable average concentrations and ranges for DMP, DEP, DnBP, and DEHP were 0.02 (0.01-0.02), 0.07 (0.06-0.09), 0.55 (0.47-0.66), and 0.30 (0.26-0.34) µg/L, respectively. The main factors determining PAE concentrations were the year and season of sampling, whereas sampling points were not among the factors influencing PAE levels. The distribution of PAEs in the water body was characterized by (i) an even distribution of minor hydrophilic DMP and DEP congeners in the whole water body, (ii) a maximum concentration of hydrophobic DnBP and DEHP congeners in the upper and near-bottom layers of the water column, and (iii) a low concentration of hydrophobic congeners in the near-shore area. The main PAE source was found to be the atmospheric transfer of polluted air masses, while the supply of PAEs from coastal sources to the pelagic zone was low. The contribution of biogenic sources to the background level of PAEs in the surface waters of Lake Baikal was established. The ecological risk of the background concentration level of PAEs for Lake Baikal biota was estimated. It was found that (i) DMP and DEP congeners do not represent a risk, or represent a very low risk, (ii) the concentration levels of dominant DnBP and DEHP congeners represent a low risk for crustaceans and fishes but (iii) a rather high risk for algae at a DEHP concentration of 0.30 µg/L.

Dataset comprising pesticides, pharmaceuticals and personal care products, and industrial chemicals detected in streams and rivers of Central Chile.

Chemical pollution caused by synthetic organic chemicals at low concentrations in the environment poses a growing threat to the ecological status of aquatic ecosystems. These chemicals are regularly released into surface waters through both treated and untreated effluents from wastewater treatment plants (WWTPs), agricultural runoff, and industrial discharges. Consequently, they accumulate in surface waters, distribute amongst environmental compartments according to their physicochemical properties, and cause adverse effects on aquatic organisms. Unfortunately, there is a lack of data regarding the occurrence of synthetic organic chemicals, henceforth micropollutants, in South American freshwater ecosystems, especially in Chile. To address this research gap, we present a comprehensive dataset comprising concentrations of 153 emerging chemicals, including pesticides, pharmaceutical and personal care products (PPCPs), surfactants, and industrial chemicals. These chemicals were found to co-occur in surface waters within Central Chile, specifically in the River Aconcagua Basin. Our sampling strategy involved collecting surface water samples from streams and rivers with diverse land uses, such as agriculture, urban areas, and natural reserves. For sample extraction, we employed an on-site large-volume solid phase extraction (LVSPE) device. The resulting environmental extracts were then subjected to wide-scope chemical target screening using gas chromatography and liquid chromatography high-resolution mass spectrometry (GC- and LC-HRMS). The dataset we present holds significant value in assessing the chemical status of water bodies. It enables comparative analysis of pollution fingerprints associated with emerging chemicals across different freshwater systems. Moreover, the data can be reused for environmental risk assessment studies. Its utilisation will contribute to a better understanding of the impact and extent of chemical pollution in aquatic ecosystems, facilitating the development of effective mitigation strategies.

Polymorphism and mutational diversity of virulence (vcgCPI/vcgCPE) and resistance determinants (aac(3)-IIa, (aacC2, strA, Sul 1, and 11) among human pathogenic Vibrio species recovered from surface waters in South-Western districts of Uganda.

BACKGROUND: Vibrio species are among the autochthonous bacterial  populations found in surface waters and associated with various life-threatening extraintestinal diseases, especially in human populations with underlying illnesses and wound infections. Presently, very diminutive information exists regarding these species' mutational diversity of virulence and resistance genes. This study evaluated variations in endonucleases and mutational diversity of the virulence and resistance genes of Vibrio isolates, harboring virulence-correlated gene (vcgCPI), dihydropteroate synthase type 1 and type II genes (Sul 1 and 11), (aadA) aminoglycoside (3'') (9) adenylyltransferase gene, (aac(3)-IIa, (aacC2)a, aminoglycoside N(3)-acetyltransferase III, and (strA) aminoglycoside 3'-phosphotransferase resistance genes. METHODS: Using combinations of molecular biology techniques, bioinformatics tools, and sequence analysis. RESULTS: Our result revealed various nucleotide variations in virulence determinants of V. vulnificus (vcgCPI) at nucleotide positions (codon) 73-75 (A → G) and 300-302 (N → S). The aminoglycosides resistance gene (aadA) of Vibrio species depicts a nucleotide difference at position 482 (A → G), while the aminoglycosides resistance gene (sul 1 and 11) showed two variable regions of nucleotide polymorphism (102 and 140). The amino acid differences exist with the nucleotide polymorphism at position 140 (A → E). The banding patterns produced by the restriction enzymes HinP1I, MwoI, and StyD4I showed significant variations. Also, the restriction enzyme digestion of protein dihydropteroate synthase type 1 and type II genes (Sul 1 and 11) differed significantly, while enzymes DpnI and Hinf1 indicate no significant differences. The restriction enzyme NlaIV showed no band compared to reference isolates from the GenBank. However, the resistant determinants show significant point nucleotide mutation, which does not produce any amino acid change with diverse polymorphic regions, as revealed in the restriction digest profile. CONCLUSION: The described virulence and resistance determinants possess specific polymorphic locus relevant to pathogenomics studies, pharmacogenomic, and control of such water-associated strains.

Deep mining of reported emerging contaminants in China's surface water in the past decade: Exposure, ecological effects and risk assessment.

The identification and management of high-risk contaminants have raised great concern from governments. Facing the growing amount of data on the occurrence of emerging contaminants (ECs) in surface water, a deep mining and quality control strategy was developed to integrate data on all reported ECs in Chinese surface water over the past decade, and an exposure and effect database was further built. In addition, multilevel risk characterization was carried out to prioritize high-risk areas, contaminants and endpoints. A total of 1038 ECs, mainly pharmaceutical and personal care products (PPCPs) and industrial chemicals, were curated, with concentrations ranging from 0.02 pg/L to 533 µg/L. For individual risk, all the provinces had acceptable risks except for Henan, which was characterized with a medium chronic risk. Nine ECs, including 4-nonylphenol and estrone, dominated individual risks. Conversely, for multisubstance risk, 76.20% and 73.87% of aquatic organisms were affected acutely and chronically at the national level, with acute and chronic risks exceeding the safety threshold of 5% in 11 and 19 provinces, respectively. Nineteen ECs, including sitosterol and chyfluthrin, dominated the multisubstance risk. In addition, 9 MoAs mainly inducing electron transfer inhibition, neurotoxicity and narcosis toxicity are high-risk endpoints. The study revealed the ecological risk status and key risk entities of Chinese surface waters, which provided the latest data to support the control of ECs in China.

Global modeling of lake-water indirect photochemistry based on the equivalent monochromatic wavelength approximation: The case of the triplet states of chromophoric dissolved organic matter.

Chromophoric dissolved organic matter (CDOM) plays key role as photosensitizer in sunlit surface-water environments, and it is deeply involved in the photodegradation of contaminants. It has recently been shown that sunlight absorption by CDOM can be conveniently approximated based on its monochromatic absorption at 560 nm. Here we show that such an approximation allows for the assessment of CDOM photoreactions on a wide global scale and, particularly, in the latitude belt between 60°S and 60°N. Global lake databases are currently incomplete as far as water chemistry is concerned, but estimates of the content of organic matter are available. With such data it is possible to assess global steady-state concentrations of CDOM triplet states (3CDOM*), which are predicted to reach particularly high values at Nordic latitudes during summer, due to a combination of high sunlight irradiance and elevated content of organic matter. For the first time to our knowledge, we are able to model an indirect photochemistry process in inland waters around the globe. Implications are discussed for the phototransformation of a contaminant that is mainly degraded by reaction with 3CDOM* (clofibric acid, lipid regulator metabolite), and for the formation of known products on a wide geographic scale.

Chemical Survey and Risk Assessment of 56 Pesticides in the Sado River Estuary (Iberian Peninsula, Portugal).

The Sado basin (~8000 km2) is an area where intensive agriculture occurs. However, this region still has few data about the water levels of priority pesticides such as fungicides, herbicides, and insecticides. Therefore, water samples were collected every two months at nine sites along the Sado River Estuary and analyzed by GC-MS/MS to determine the influx of pesticides in that ecosystem. More than 87% of the pesticides were quantified, and 42% and 72% were above the maximum totals established by the European Directives 98/83/EC and 2013/39/EU, respectively. Fungicides (91%), herbicides (87%), and insecticides (85%) attained average annual amounts of ≈3.2 µg/L, ≈1.0 µg/L, and ≈12.8 µg/L, respectively. A mathematical approach was used to evaluate the hazard of the pesticide mixture at the maximum concentrations found in this area. The assessment identified invertebrates as the most at-risk trophic level and identified two chemicals (chlorpyriphos and cyfluthrin) as the primary culprits. This assumption was supported by acute in vivo assays using Daphnia magna. These observations, and the high concentrations of phosphates, indicate that the status of the Sado waters poses environmental and potential human health risks.