The study was conducted to assess surface water quality in Ca Mau peninsula using multivariate statistical analysis. Fifty-one water samples with the parameters of pH, dissolved oxygen (DO), total suspended solids (TSS), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), ammonium (N-NH4+), orthophosphate (P-PO43-) and total coliform were used in the evaluation. Water quality is assessed using national standard and water quality index (WQI). The methods of cluster (CA), discriminant (DA), principal component analysis (PCA) were used to analyze the variation patterns of water quality. The surface water was contaminated with organic matters, suspended solids, nutrients, and microorganisms. DA revealed that DO, TSS, BOD5 and pH contributed 76.91% to the seasonal variation of water quality. Water quality is classified from bad to heavily polluted. CA grouped water quality into 7 clusters and DO, TSS, BOD5, COD and coliform of the clusters 1-3 were significantly higher than those of the clusters 4-7. PCA presented that PC1-PC3 was the main sources affecting water quality, explaining 85.45% of the variation in water quality. The sources of pollution can be human (domestic wastewater, waste from agriculture, fisheries, industry, landfills), natural (hydrological regime, rainwater overflow, river bank erosion). pH, DO, BOD5, COD, TSS, N-NH4+, P-PO43- and coliform have an impact on water quality and need to be continuously monitored. However, for the multivariate statistical method to be more effective, an initial data set with several water quality parameters sampling locations is needed. The current results provide scientific information and support local water quality monitoring activities.

The fetus is prenatally exposed to a mixture of organochlorine pesticides (OCPs), mercury (Hg), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and selenium (Se) through maternal seafood consumption in real-life scenario. Prenatal exposure to these contaminants and nutrients has been suggested to affect thyroid hormone (TH) status in newborns, but the potential relationships between them are unclear and the joint effects of the mixture are seldom analyzed. The aim of the study is to investigate the associations of prenatal exposure to a mixture of OCPs, Hg, DHA, EPA and Se with TH parameters in newborns. 228 mother-infant pairs in Shanghai, China were included. We measured 20 OCPs, total Hg, DHA, EPA and Se in cord blood samples as exposure variables. The total thyroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3), free triiodothyronine (FT3), and thyroid-stimulating hormone (TSH) levels and the FT3/FT4 ratio in cord serum were determined as outcomes. Using linear regression models, generalized additive models and Bayesian kernel machine regression, we found dose-response relationships of the mixture component with outcomes: among the contaminants, p,p'-DDE was the most important positive predictor of TT3, while HCB was predominantly positively associated with FT3 and the FT3/FT4 ratio, indicating different mechanisms underlying these relationships; among the nutrients, EPA was first found to be positively related to the FT3/FT4 ratio. Additionally, we found suggestive evidence of interactions between p,p'-DDE and HCB on both TT3 and FT3, and EPA by HCB interactions for TT3, FT3 and FT3/FT4 ratio. However, the overall effects of the mixture on thyroid hormone parameters were not significant. Our result suggests that prenatal exposure to p,p’-DDE, HCB and EPA as part of a mixture might affect thyroid function of newborns in independent and interactive ways. The potential biological mechanisms merit further investigation.

Micro and nanoplastics are new generation contaminants of global concern. It is important to evaluate the effects on edible products due to the presence of micro- and nano-sized plastics in the treated wastewater. A hydroponic experiment was carried out to explore the effect of polsytrene nanoplastics (PS-NPs; 20 nm) at different concentrations (0, 12.5, 25, and 50 mg L⁻¹) on Glycine max L. (soybean) seedlings for 7-days. In the current study, firstly the uptake of PS-NPs by Glycine max L. (soybean) roots were confirmed by laser confocal scanning microscope. Exposure to PS-NPs, negatively affected growth parameters and increased Fe, Zn and Mn contents in roots and leaves of soybean seedlings. PS-NPs treatments caused oxidative stress in soybean seedlings. The hydrogen peroxide and malondialdehyde contents, showed similar increase pattern in seedlings exposed to PS-NPs. Response to PS-NPs, the level of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and guaiacol peroxidase) and proline content were generally enhanced in roots and leaves of soybean. The expression level of stress-related genes examined in the study included CSD5, FSD3, APX1, and POD up-regulated in PS-NPs treated-soybean seedlings in a tissue specific manner. The results of the present study showed the adverse effects of PS-NPs on soybean seedlings, which may have important implications for the risk assessment of NPs on crop production and environmental safety.

Water shortages are an issue of growing worldwide concern. Irrigated agriculture accounts for about 70% of total freshwater withdrawals globally, therefore alternatives to use of conventional sources need to be investigated. This paper critically reviews the application of treated wastewater for agricultural fertigation (i.e., water and nutrient recovery) considering different perspectives: legislation, agronomic characteristics, social acceptability, sustainability of treatment technologies. Critical issues that still need further investigation for a wider application of fertigation practices include accumulation of emerging contaminants in soils, microbiological and public health implications, and stakeholders' acceptance. A techno-economic methodological approach for assessing the sustainability of treated wastewater reuse in agriculture is subsequently proposed herein, which considers different possible local conditions (cultivated crops and effluent characteristics). The results showed that tailoring effluent characteristics to the desired nutrient composition could enhance the process economic sustainability; however, water savings have a major economic impact than fertilizers’ savings, partly due to limited P reuse efficiency. The developed methodology is based on a practical approach and may be generalized to most agricultural conditions, to evaluate and encourage safe and efficient agricultural wastewater reuse practices.

Headwater streams are a hotspot of freshwater biodiversity, carrying indispensable resource pools of aquatic species. However, up to now, there remain many challenges to accurately and efficiently characterize the responses of this vulnerable ecosystem to human-induced changes. Here, we collected macroinvertebrate data from 12 different headwater streams in the Liao River of northeast China by DNA metabarcoding approach, to reveal biodiversity changes and ecological thresholds affected by human beings. Our data showed that the community composition and structure of headwater streams had unique and significant differences under human impacts, and 5-day biological oxygen demand (BOD₅) and ammonia nitrogen (NH₃–N) were the key variables explaining the variation in community structure. Although α diversity had a unimodal relationship with nutrients and organic loads, β diversity and its turnover component (species replacement) increased significantly. In addition, 22 and 33 indicative taxa were identified to have significant negative responses to BOD₅ and NH₃–N, respectively, and the change points derived from Threshold Indicator Taxa Analysis (TITAN) for the negative response of their frequency and abundance were BOD₅ >3.42 mg/L and NH₃–N >0.14 mg/L. Overall, this study reveals the biodiversity changes in headwater streams from the aspects of α and β diversity, and also determines the thresholds of BOD₅ and NH₃–N pollutants for one reach at one date from 12 headwater streams, suggesting the potential of DNA metabarcoding approach for threshold analyses in headwater streams.

Land application of sewage sludge is increasingly used as an alternative to landfilling and incineration owing to a considerable content of carbon and essential plant nutrients in sewage sludge. However, the presence of chemical and biological contaminants in sewage sludge poses potential dangers; therefore, sewage sludge must be suitably treated before being applied to soils. The most common methods include anaerobic digestion, aerobic composting, lime stabilization, incineration, and pyrolysis. These methods aim at stabilizing sewage sludge, to eliminate its potential environmental pollution and restore its agronomic value. To achieve best results on land, a comprehensive understanding of the transformation of organic matter, nutrients, and contaminants during these sewage-sludge treatments is essential; however, this information is still lacking. This review aims to fill this knowledge gap by presenting various approaches to treat sewage sludge, transformation processes of some major nutrients and pollutants during treatment, and potential impacts on soils. Despite these treatments, overtime there are still some potential risks of land application of treated sewage sludge. Potentially toxic substances remain the main concern regarding the reuse of treated sewage sludge on land. Therefore, further treatment may be applied, and long-term field studies are warranted, to prevent possible adverse effects of treated sewage sludge on the ecosystem and human health and enable its land application.

This study assessed the potential of the New Zealand mud snail Amphibola crenata to act as a bioindicator of contaminated estuarine sediment. Seventeen sites with varying contaminant burdens were identified within six New Zealand regions. Attributes (population density, individual length distribution and individual dry weight condition index) were measured for field-collected A. crenata, and related to measurements of sediment trace metals and nutrients. Population density of the mud snail was relatively high in sites with elevated nutrients and organic matter. The length distribution of A. crenata showed significant regional and site-specific variations. Minimum, mean, and median shell length of A. crenata were positively correlated with sediment cadmium and zinc concentration. Overall, the sites were able to be distinguished by A. crenata population attributes and the sediment metal and nutrient content. These results suggest that A. crenata population information has potential value for assessing estuarine sediment metal and nutrient contamination.

Ecosystem based water quality models are important tools for prognostic site assessment and evaluation of ecosystem-performance of marine fish farms. We present the development and application of a comprehensive Fish Culture Zone Water Quality Model using continuous bi-weekly field data over a six-year period (2012–2017). The model simulates five interacting subsystems: phytoplankton, phosphorus and nitrogen cycles, and the dissolved oxygen (DO) and particulate organic carbon balance. The application of the model to two fish culture zones in Hong Kong shows the model captures the trends of nutrient and DO variation and the performance in quantitative prediction of algal biomass is challenging. The effect of errors in the specification of primary model inputs are evaluated using dimensionless sensitivity coefficients based on First Order Variance Analysis reveals the relative importance of fish stock (loading), physical size (volume), tidal flushing rate and boundary conditions in the prediction of key water quality variables.

Phytoplankton assemblage and chlorophyll a along the salinity gradient and oxygen zonation were studied in Ulhas Estuary. Oxic condition exist in euhaline region of the estuary that receives oxygenated coastal waters, while, poly-meso-oligohaline region is hypoxic due to the accumulation of voluminous amount of pollutants from industrial effluents, domestic/sewage and agricultural discharges. Additionally, anthropogenically generated nutrients enhanced phytoplankton biomass (chlorophyll a) and their senescence also led to hypoxia. The dominance of diatoms (>70%) was observed in the euhaline-oxic region, while a tremendous decrease in their contribution (18%) was observed in the oligohaline region. Meso to oligohaline region of the estuary is governed by cyanophytes and chlorophytes due to their affinity towards low salinity and high dissolved inorganic nutrients. Carlson's Trophic State Index (TSI) further substantiated the estuary as eutrophic. Additionally, the study could identify the adaptation of cyanophytes and chlorophytes in oxygen deficient water.

We investigated the composition, source, and reactivity of sedimentary organic matter (OM) present in aquaculture systems along the Korean coast. A multi-isotopic approach was applied to 216 surface sediments from five sections: western (W)-1, W-2, southern (S)-1, S-2, and eastern (E)-1 sections. The ¹⁵N-enriched total nitrogen signatures in the surface sediments of the W-1 section may indicate that a substantial fraction of sedimentary OM has anthropogenic origins exported through the Han River. Simultaneously, the deposition of allochthonous OM is predominant in the S sections (Jinhae and Masan Bays). The ³⁴S-depleted patterns at the S-2 section may indicate that sulfate reduction occurring at the sedimentary boundary contributes to active OM decomposition, depending on the increased sedimentation of the aquaculture-derived OM. Our results highlight that isotopic-based source tracking near aquaculture systems provide important information for identifying anthropogenic contamination in coastal marine sediments and for improving environmental management.