Pesticides are widely used to alleviate pest pressure in agricultural systems, and atrazine is a typical diffuse pollutant and serves a sensitivity index for environmental characteristics. Based on the physicochemical properties of parent substances, degradation products of pesticides may pose a greater threat to aquatic ecosystems than pesticides. Atrazine and three primary degradation products (deethylatrazine (DEA), deisopropylatrazine (DIA) and didealkylatrazine (DDA)) were investigated in a semienclosed bay of the western Pacific Ocean. Seasonal surface water and suspended particulate sediment (SPS) samples were collected from the estuary and bay in January, April, and August 2019. The level of pesticide contamination was lower in the bay than in the estuary, and the pesticide concentration in the dissolved phase was higher than that in the adsorbed phase. The average concentrations of atrazine and the three degradation products in the three seasons ranged from 2.42 to 328.46 ng/L in water and from 0.07 to 12.75 ng/L in SPS. The proportion of atrazine among the four detected pollutants decreased from 0.7 to 0.1 in surface water and from 0.3 to 0.1 in SPS over the seasons. As the main degradation products, the concentration proportions of DDA and DEA reached as high as 0.6 in August. The ratio of DEA to atrazine (DEA/ATR) increased from January to August, which indicated the progressive degradation process in the bay. Single-factor analysis of variance and principal component analysis indicated that atrazine degradation was sensitive to temperature, dissolved oxygen, and salinity. These three factors accounted for almost 70% of the seasonal variance in atrazine without a quantification assessment of photolysis or bacteria. The spatial distributions of DEA in the three seasons demonstrated that wind and currents also played important roles in pollutant redistribution. The seasonal temporal and spatial correlations between water and SPS demonstrated the degradation patterns of atrazine in marine conditions, supporting the need for future detailed toxicity studies.

Previous studies have detected numerous organic contaminants and in vitro bioactivities in surface water from the South Platte River near Denver, Colorado, USA. To evaluate the temporal and spatial distribution of selected contaminants of emerging concern, water samples were collected throughout 2018 and 2019 at 11 sites within the S. Platte River and surrounding tributaries with varying proximities to a major wastewater treatment plant (WWTP). Water samples were analyzed for pharmaceuticals, pesticides, steroid hormones, and wastewater indicators and screened for in vitro biological activities. Multiplexed, in vitro assays that simultaneously screen for agonistic activity against 24 human nuclear receptors detected estrogen receptor (ER), peroxisome proliferator activated receptor-gamma (PPARγ), and glucocorticoid receptor (GR) bioactivities in water samples near the WWTP outflow. Targeted in vitro bioassays assessing ER, GR, and PPARγ agonism corroborated bioactivities for ER (up to 55 ± 9.7 ng/L 17β-estradiol equivalents) and GR (up to 156 ± 28 ng/L dexamethasone equivalents), while PPARγ activity was not confirmed. To evaluate the potential in vivo significance of the bioactive contaminants, sexually-mature fathead minnows were caged at six locations upstream and downstream of the WWTP for 5 days after which targeted gene expression analyses were performed. Significant up-regulation of male hepatic vitellogenin was observed at sites with corresponding in vitro ER activity. No site-related differences in GR-related transcript abundance were detected in female adipose or male livers, suggesting observed environmental concentrations of GR-active contaminants do not induce a detectable in vivo response. In line with the lack of detectable targeted in vitro PPARɣ activity, there were no significant effects on PPARɣ-related gene expression. Although the chemicals responsible for GR and PPAR-mediated bioactivities are unknown, results from the present study provide insights into the significance (or lack thereof) of these bioactivities relative to short-term in situ fish exposures.

Two different methodologies were combined to evaluate the risks that antibiotics can pose in the environment; i) an effect-based methodology based on microbial growth inhibition and ii) an analytical method based on liquid-chromatography coupled to mass spectrometry (LC-MS). The first approach was adapted and validated for the screening of four antibiotic families, specifically macrolides/β-lactams, quinolones, sulfonamides and tetracyclines. The LC-MS method was applied for the identification and quantification of target antibiotics; then, the obtained results were combined with ecotoxicological data from literature to determine the environmental risk. The two methodologies were used for the analysis of antibiotics in water samples (wastewater, river water and seawater) and biofluids (fish plasma and mollusk hemolymph) in two monitoring campaigns undertaken in the Ebro Delta and Mar Menor Lagoon (both in the Mediterranean coast of Spain). Both approaches highlighted macrolides (azithromycin) and quinolones (ciprofloxacin and ofloxacin) as the main antibiotics in wastewater treatment plant (WWTP) effluents with potential risk for the environment. However, no risk for the aquatic life was identified in the river, lagoon and seawater as antibiotic levels were much lower than those in WWTP effluents. Fish from Ebro River were the organisms presenting the highest antibiotic concentration when compared with bivalves (mussels) from the Mediterranean Sea and gastropods (marine snails) from the Mar Menor Lagoon. The effect-based methodology successfully determined antibiotic risk in wastewater, but its applicability was less clear in environmental waters such as seawater, due to its high detection limits. Improving sample preconcentration could increase the method sensibility. Overall, combination of both methodologies provides comprehensive insights in antibiotic occurrence and risk associated in areas under study.

The distribution of freshwater and marine microplastics (MPs) varies due to the difference in fresh and seawater densities and MP sources. This study aims to investigate the abundance of MPs and their possible sources in surface waters of different ecosystems, such as sea, lagoon, and lake. We classified MPs in terms of their color and type and established the relationship between the MPs in surface waters with different characteristics. The mean MP abundance (33 particles L⁻¹) detected herein was higher than that in the previously conducted studies. Fragment particles (37.95%) were determined to be the dominant MP type, and the predominant MP color was blue (75.28%). As for the seasonal MP distribution, its highest content (48.03 particles L⁻¹) was observed in autumn, unlike that reported by other studies. The findings of this study reveal the effects of wastewater treatment plant (WWTP) discharge and current flow on the MP distribution in the study area. This study aims to provide representative data on the MP abundance and distribution, as well as MP-affecting parameters for similar aquatic areas in other parts of the world.

Water pollution by veterinary antibiotics (VAs) resulting from livestock production is associated with severe environmental and human health risks. While upward trends in global animal product consumption signal that these risks might exacerbate toward the future, VA related water pollution is currently insufficiently understood. To increase this understanding, the present research assesses processes influencing VA pollution from VA administration to their discharge into freshwater bodies, using an integrated modelling approach (IMA). For the VAs amoxicillin, doxycycline, oxytetracycline, sulfamethazine, and tetracycline we estimate loads administered to livestock, excretion, degradation during manure storage, fate in soil and transport to surface water. Fate and transport are modelled using the VA transport model (VANTOM), which is fed with estimates from the Pan-European Soil Erosion Risk Assessment (PESERA). The grey water footprint (GWF) is used to indicate the severity of water pollution in volumetric terms by combining VA loads and predicted no effect concentrations. We apply our approach to the German-Dutch Vecht river catchment, which is characterized by high livestock densities. Results show a VA mass load decrease larger than 99% for all substances under investigation, from their administration to surface water emission. Due to metabolization in the body, degradation during manure storage and degradation in soil, VA loads are reduced by 45%, 80% and 90% on average, respectively. While amoxicillin and sulfamethazine dissipate quickly after field application, significant fractions of doxycycline, oxytetracycline and tetracycline accumulate in the soil. The overall Vecht catchment's GWF is estimated at 250,000 m³ yr⁻¹, resulting from doxycycline (81% and 19% contribution from the German and Dutch catchment part respectively). Uncertainty ranges of several orders of magnitude, as well as several remaining limitations to the presented IMA, underscore the importance to further develop and refine the approach.

In recent years, with the expansion of the Weining county in the northeast of Caohai wetland, the construction of a new port in the north, and the large-scale development of cultivated land in the east, land use patterns in lakeshore areas have changed. These changes have affected the state of lake shores water bodies in complex ways, resulting in varying degrees of local water pollution. To explore the distribution and transformation characteristics of water chemistry and heavy metals in different areas of a water body under the influence of different land uses, especially the interactions between water chemical factors and heavy metals in different areas of a water body, this study used Circos diagrams, originally used in biological genetic analysis, to visualize these interactions. This is the first time that the Circos diagram has been applied to the analysis of environmental interactions. The results showed that there are significant differences in the distribution of water chemical factors and heavy metals in different areas of the Caohai wetland. In particular, Cd is affected by anthropogenic sources. The Cd content is higher in the NCL and UL areas, which are at greater risk from pollution. The factors controlling heavy metal levels in water bodies were different in the different regions. The NCL region was mainly affected by construction excavation ore, UL was mainly affected by man-made industrial inputs, CL was mainly affected by pesticide and fertilizer inputs, and ML and FL were mainly affected by Eh and DO. The PCA results showed that the sources of heavy metals in different types of water bodies in the lakeshore zone were both natural and anthropogenic. Therefore, controlling pollutants, reducing environmental pollution inputs to the lakeshore zone, and strengthening supervision and management near wetlands may be of great significance for handling heavy metal pollution.

To accurately visualize the spatial distribution of heavy metal pollution and provide basic information on soil remediation in dairy farm, Geographic Information System (GIS) is used for optimization of sample collection and data analysis. Based on GIS technology, dairy manure, 10 cm-depth surface soil, 50 cm-depth sub soil, and surface water samples were collected from dairy farm in Dulbert Mongolian Autonomous County, Daqing City, Heilongjiang Province in China. The spatial distribution and assessment of heavy metals were performed by using GIS inverse distance weighted interpolation and pollution index method. The single factor pollution index value of As element in the soil was found to indicate the class of extreme contamination, whereas Ni in both surface water inside and outside the farm, and Sb in the cow drinking water were assigned to the level of moderate contamination. The comprehensive pollution index implied serious contamination for soil samples, slight contamination for water samples and safety for manure samples, respectively. Comprehensive score for heavy metal elements followed the orders of As>Zn>Cr>Ni>Cu>Pb>Cd>Hg. The horizontal pollution that mainly occurred in the middle and east regions was increased from north to south, and west to east district. Historically, the dairy farm belonged to heavily polluted saline-alkali soil, where the heavy metals might enter the food chain through transportation from soil to water, the cows, and eventually to the milk and human body. Visualizing spatial distribution of heavy metal contamination by using GIS technology will be of significance to provide useful information for soil remediation of dairy farm.

Eutrophic freshwater lake ecosystems are receiving increasing public attention due to a global increase in large-scale harmful cyanobacterial blooms in surface waters. However, the contribution of phytodetritus accumulation in benthic sediments post-bloom remains unclear. In this study, field investigations were performed using microsensors to evaluate benthic phytodetritus mats by measuring TOC/TN ratios, pigments, biodegradable compounds and odorants as descriptive parameters. Results show that the massive amount of phytodetritus trapped by aquatic plants gradually evolved into benthic cyanobacterial detritus mats, which were characterized as anoxic, reductive and low pH. It was confirmed that the occurrence of odorants is more serious in the detritus mats due to decay and decomposition of the accumulated phytodetritus. The mean odorant content in the vegetated zones was 3–52 times higher than that in the unvegetated zones. The dominant odorants were dimethyl trisulfide (DMTS), β-ionone and β-cyclocitral, with mean contents of 52.38 ng·(g·dw)-1, 162.20 ng·(g·dw)-1 and 307.51 ng·(g·dw)-1, respectively, in the sediment. In addition, odorant production appears to be associated with the distribution of biodegradable compounds in the sediment. This is supported by the marked correlation observed between biodegradable compounds and odorants. Multiple regression analysis showed that biodegradable compounds can be used as indicators to predict odorant content in the sediment. It is noteworthy that the odorant trend in the water column and sediment is symmetrical, indicating a risk of diffusion from the sediment to the water column. This study helps to clarifying the contributions of benthic cyanobacterial detritus mats to odorant production in shallow eutrophic lakes. The information provided herein may also be useful for future management of aquatic ecosystems.

Cryptosporidium and Giardia are important parasites due to their zoonotic potential and impact on human health, often causing waterborne outbreaks of disease. Detection of (oo)cysts in water matrices is challenging and few countries have legislated water monitoring for their presence. The aim of this study was to investigate the presence and origin of these parasites in different water sources in Northern Greece and identify interactions between biotic/abiotic factors in order to develop risk-assessment models. During a 2-year period, using a longitudinal, repeated sampling approach, 12 locations in 4 rivers, irrigation canals, and a water production company, were monitored for Cryptosporidium and Giardia, using standard methods. Furthermore, 254 faecal samples from animals were collected from 15 cattle and 12 sheep farms located near the water sampling points and screened for both parasites, in order to estimate their potential contribution to water contamination. River water samples were frequently contaminated with Cryptosporidium (47.1%) and Giardia (66.2%), with higher contamination rates during winter and spring. During a 5-month period, (oo)cysts were detected in drinking-water (<1/litre). Animals on all farms were infected by both parasites, with 16.7% of calves and 17.2% of lambs excreting Cryptosporidium oocysts and 41.3% of calves and 43.1% of lambs excreting Giardia cysts. The most prevalent species identified in both water and animal samples were C. parvum and G. duodenalis assemblage AII. The presence of G. duodenalis assemblage AII in drinking water and C. parvum IIaA15G2R1 in surface water highlights the potential risk of waterborne infection. No correlation was found between (oo)cyst counts and faecal-indicator bacteria. Machine-learning models that can predict contamination intensity with Cryptosporidium (75% accuracy) and Giardia (69% accuracy), combining biological, physicochemical and meteorological factors, were developed. Although these prediction accuracies may be insufficient for public health purposes, they could be useful for augmenting and informing risk-based sampling plans.

Antibiotic resistance is a major public health concern. Triclosan is an antimicrobial compound with direct links to antibiotic resistance that was widely used in soaps in the U.S. until its ban by the U.S. Food and Drug Administration. Benzalkonium chloride (BAC), a quaternary ammonium compound, has widely replaced triclosan in soaps marketed as an antibacterial. BAC has been detected in surface waters and its presence will likely increase following increased use in soap products. The objective of this study was to determine the effect of BAC on relative abundance of antibiotic resistance in a bacterial community from a surface water used as a source for drinking water treatment. Bench-scale microcosm experiments were conducted with microbial communities amended with BAC at concentrations ranging from 0.1 μg L⁻¹ to 500 μg L⁻¹. Phenotypic antibiotic resistance was quantified by culturing bacteria in the presence of different antibiotics, and genotypic resistance was determined using qPCR to quantify antibiotic resistance genes (ARGs). BAC at concentrations ranging from 0.1 μg L⁻¹ to 500 μg L⁻¹ was found to positively select for bacteria resistant to ciprofloxacin and sulfamethoxazole, and negatively select against bacteria with resistance to six other antibiotics. Exposure to BAC for 14 days increased the relative abundance of sul1 and blaTEM. This study re-highlights the importance of employing both culture and non-culture-based techniques to identify selection for antibiotic resistance. The widespread use of BAC will likely impact antibiotic resistance profiles of bacteria in the environment, including in source waters used for drinking water, wastewater treatment plants, and natural waterways.