Environmental DNA reveals the spatiotemporal distribution and migration characteristics of the Yangtze finless porpoise, the sole aquatic mammal in the Yangtze River.

The Yangtze Finless Porpoise (YFP) is one of the 13 global flagship species identified by the World Wildlife Fund and is classified as "Critically Endangered." It is also the only extant aquatic mammal in the Yangtze River. In this study, 44 sampling points were deployed across the middle and lower reaches of the Yangtze River, with vertical sampling sections established in four key areas. Using environmental DNA (eDNA) and species distribution model(SDM), we explored the spatiotemporal distribution of YFPs and predicted their potential suitable habitats. The results indicate that the YFP has a relatively wide distribution during the flood season but exhibits clustering behavior during the dry season, showing a patchy distribution and a migratory trend from the midstream to downstream of the main channel. Predictions using the MAXENT model reveal varying trends in suitable habitat under different scenarios. Overall, YFP's potential habitat is expected to expand by 2050, but due to rising temperatures, it will contract by 2070. Elevation (dem, 65.4%), human footprint index (hfp, 8.8%), and isothermality (bio3, 8%) are key factors influencing habitat suitability. These findings demonstrate that eDNA is an effective tool for monitoring large aquatic organisms and provide scientific evidence for the conservation of the YFP.

Salinity influence correction for zinc ion seawater quality criteria and ecological risk assessment in Chinese seas.

The increasing prevalence of zinc pollution in marine ecosystems, primarily from industrial sources, has become a global environmental concern. This study addresses zinc toxicity in Chinese coastal waters, emphasizing the importance of considering environmental factors like salinity and temperature in establishing water quality criteria (WQC). Data collected from various marine regions underwent meticulous analysis, incorporating salinity corrections to derive more precise criteria values. The short-term criteria for the Bohai Sea, Yellow Sea, East China Sea, and South China Sea were 94.0, 77.6, 84.2, and 118 µg/L under the salinity correction, respectively, and the long-term criteria was 4.10 µg/L. Ecological risk assessments employing diverse methodologies revealed varying levels of risk across sea areas, underscoring the nuanced nature of zinc pollution's impact on marine ecosystems. Greater acute and chronic risk of zinc ions observed in the Yellow Sea region. These findings underscore the imperative need for tailored management strategies to protect local marine life from the environmental threats posed by zinc.

Effects of Environmental Organic Pollutants on Environment and Human Health: The Latest Updates.

This editorial introduces the Special Issue "Effects of Environmental Organic Pollutants on Environment and Human Health: The Latest Updates" [...].

The application of human-derived cell lines in neurotoxicity studies of environmental pollutants.

As industrial and societal advancements progress, an increasing number of environmental pollutants linked to human existence have been substantiated to elicit neurotoxicity and developmental neural toxicity. For research in this field, human-derived neural cell lines have become excellent in vitro models. This study examines the utilization of immortalized cell lines, specifically the SH-SY5Y human neuroblastoma cell line, and neural cells derived from human pluripotent stem cells, in the investigation of neurotoxicity and developmental neural toxicity caused by environmental pollutants. The study also explores the culturing techniques employed for these cell lines and provides an overview of the standardized assays used to assess various biological endpoints. The environmental pollutants involved include a variety of organic compounds, heavy metals, and microplastics. The utilization of cell lines derived from human sources holds significant significance in elucidating the neurotoxic effects of environmental pollutants and the underlying mechanisms. Finally, we propose the possibility of improving the in vitro model of the human nervous system and the toxicity detection methods.

Environmental DNA unveiling the fish community structure and diversity features in the Yangtze River basin.

Fish, as top predators in aquatic ecosystems, play an important role in maintaining the structure and functioning of these ecosystems, making their diversity a topic of great interest. This study focused on the Yangtze River Basin to investigate the fish community structure and diversity using environmental DNA (eDNA) technology. The results showed that a total of 71616 fish operational taxonomic units (OTUs) and 90 fish belonging to 23 families were detected, with the Cyprinidae family being the dominant group, followed by the Cobitidae, Amblycipitidae, etc. Compared to historical traditional morphological fish surveys, the quantity of fish detected using eDNA was relatively low, but the overall distribution pattern of fish communities was generally consistent. The highest fish Shannon-Wiener diversity index in the Yangtze River Basin sites reaches 2.60 with an average value of 1.25. The fish diversity index was higher in the downstream compared to the middle and upstream regions, and there were significant differences among different sampling sites. Significant environmental factors influencing α-diversity included chlorophyll-a, chemical oxygen demand, dissolved oxygen, total nitrogen, and elevation. Non-metric multidimensional scaling (NMDS) analysis revealed significant differences in fish community composition between the upstream and middle/lower reaches of the Yangtze River, while the composition of fish communities in the middle and lower reaches was more similar. Redundancy analysis (RDA) indicated that total organic carbon (TOC) was positively correlated with fish community distribution in the upstream, while water temperature and NO3-N were negatively correlated with fish distribution in the upstream. NH3-N and CODMn were negatively correlated with fish distribution in the middle and downstream regions, indicating a relatively severe water pollution in these areas. Additionally, fish communities in the Yangtze River displayed a typical distance decay pattern.

BDE-209-induced genotoxicity, intestinal damage and intestinal microbiota dysbiosis in zebrafish (Danio Rerio).

The environmental presence of polybrominated diphenyl ethers (PBDEs) is ubiquitous due to their wide use as brominated flame retardants in industrial products. As a common congener of PBDEs, decabromodiphenyl ether (BDE-209) can pose a health risk to animals as well as humans. However, to date, few studies have explored BDE-209's toxic effects on the intestinal tract, and its relevant mechanism of toxicity has not been elucidated. In this study, adult male zebrafish were exposed to BDE-209 at 6 µg/L, 60 µg/L and 600 µg/L for 28 days, and intestinal tissue and microbial samples were collected for analysis to reveal the underlying toxic mechanisms. Transcriptome sequencing results demonstrated a dose-dependent pattern of substantial gene differential expression in the group exposed to BDE-209, and the differentially expressed genes were mainly concentrated in pathways related to protein synthesis and processing, redox reaction, and steroid and lipid metabolism. In addition, BDE-209 exposure caused damage to intestinal structure and barrier function, and promoted intestinal oxidative stress, inflammatory response, apoptosis and steroid and lipid metabolism disorders. Mechanistically, BDE-209 induced intestinal inflammation by increasing the levels of TNF-α and IL-1ß and activating the NFκB signaling pathway, and might induce apoptosis through the p53-Bax/Bcl2-Caspase3 pathway. BDE-209 also significantly inhibited the gene expression of rate-limiting enzymes such as Sqle and 3ßhsd (p < 0.05) to inhibit cholesterol synthesis. In addition, BDE-209 induced lipid metabolism disorders through the mTOR/PPARγ/RXRα pathway. 16S rRNA sequencing results showed that BDE-209 stress reduced the richness and diversity of intestinal microbiota, and reduced the abundance of probiotics (e.g., Bifidobacterium and Faecalibacterium). Overall, the results of this study help to clarify the intestinal response mechanism of BDE-209 exposure, and provide a basis for evaluating the health risks of BDE-209 in animals.

A review of the toxic effects of ammonia on invertebrates in aquatic environments.

Aquatic invertebrates are the organisms most susceptible to ammonia toxicity. However, the toxic effects of ammonia on invertebrates are still poorly understood. This study reviews the research progress in ammonia toxicology for the period from 1986 to 2023, focusing on the effects on invertebrates. Through examining the toxic effects of ammonia at different levels of organization (community, individual, tissue and physiology, and molecular) as well as the results from omics studies, we determined that the most significant effects were on the reproductive capacity of invertebrates and the growth of offspring, although different populations show variation in their tolerance to ammonia, and tissues have varied potential to respond to ammonia stress. A multicomponent analysis is an in-depth technique employed in toxicological studies, as it can be used to explore the enrichment pathways and functional genes expressed under ammonia stress. This study comprehensively discusses ammonia toxicity from multiple aspects in order to provide new insights into the toxic effects of ammonia on aquatic invertebrates.

QSAR-QSIIR-based prediction of bioconcentration factor using machine learning and preliminary application.

Bioconcentration factor (BCF) is one of the important parameters for developing human health ambient water quality criteria (HHAWQC) for chemical pollutants. Traditional experimental method to obtain BCF is time-consuming and costly. Therefore, prediction of BCF by modeling has attracted much attention. QSAR (Quantitative Structure-Activity Relationship) model based on molecular descriptor is often used to predict BCF, however, in order to improve the accuracy of prediction, previous models are only applicable for prediction for a single category of substance and a single species, and cannot meet the needs of BCF prediction of pollutants lacing toxicity data. In this study, optimized 17 traditional molecular descriptor and five kinds of bioactivity descriptor were selected from more than 200 molecular descriptor and 25 kinds of biological activity descriptors. A QSAR-QSIIR (Quantitative Structure In vitro-In vivo Relationship) model suitable for multiple chemical substances and whole species is constructed by using optimized 4-MLP machine learning algorithm with selected molecular and bioactivity descriptors. The constructed model significantly improves the prediction accuracy of BCF. The R2 of verification set and test set are 0.8575 and 0.7924, respectively, and the difference between predicted BCF and measured BCF is mostly less than 1.5 times. Then, BCF of BTEX in Chinese common aquatic products is predicted using the constructed QSAR-QSIIR model, and the HHAWQC of BTEX in China are derived using the predicted BCF, which provides a valuable reference for establishment of China's BTEX water quality standards.

The Application of Reference Dose Prediction Model to Human Health Water Quality Criteria and Risk Assessment.

Oral reference dose (RfD) is a key parameter for deriving the human health ambient water quality criteria (AWQC) for non-carcinogenic substances. In this study, a non-experimental approach was used to calculate the RfD values, which explore the potential correlation between toxicity and physicochemical characteristics and the chemical structure of pesticides. The molecular descriptors of contaminants were calculated using T.E.S.T software from EPA, and a prediction model was developed using a stepwise multiple linear regression (MLR) approaches. Approximately 95% and 85% of the data points differ by less than 10-fold and 5-fold between predicted values and true values, respectively, which improves the efficiency of RfD calculation. The model prediction values have certain reference values in the absence of experimental data, which is beneficial to the advancement of contaminant health risk assessment. In addition, using the prediction model constructed in this manuscript, the RfD values of two pesticide substances in the list of priority pollutants are calculated to derive human health water quality criteria. Furthermore, an initial assessment of the health risk was performed by the quotient value method based on the human health water quality criteria calculated by the prediction model.

Environmental DNA sequencing reveals the regional difference in diversity and community assembly mechanisms of eukaryotic plankton in coastal waters.

The diversity and community assembly mechanisms of eukaryotic plankton in coastal waters is so far not clear. In this study, we selected the coastal waters of Guangdong-Hong Kong-Macao Greater Bay Area, which is a highly developed region in China, as the research area. By use of high-throughput sequencing technologies, the diversity and community assembly mechanisms of eukaryotic marine plankton were studied in which a total of 7,295 OTUs were obtained, and 2,307 species were annotated by doing environmental DNA survey of 17 sites consist of surface and bottom layer. Ultimately, the analysis reveals that the species abundance of bottom layer is, by and large, higher than that in the surface layer. In the bottom, Arthropoda is the first largest group, accounting for more than 20% while Arthropoda and Bacillariophyta are dominant groups in surface waters accounting for more than 40%. It is significant of the variance in alpha-diversity between sampling sites, and the difference of alpha-diversity between bottom sites is greater than that of surface sites. The result suggests that the environmental factors that have significant influence on alpha-diversity are total alkalinity and offshore distance for surface sites, and water depth and turbidity for bottom sites. Likewise, the plankton communities obey the typical distance-decay pattern. Analysis about community assembly mechanisms reveals that, overall, dispersal limitation is the major pattern of community formation, which accounts for more than 83% of the community formation processes, suggesting that stochastic processes are the crucial assembly mechanism of the eukaryotic plankton community in the study area.

Chinese Technical Guideline for Deriving Water Quality Criteria for Protection of Freshwater Organisms.

In recent years, China has determined the national goal of "developing national environmental criteria", thereby promoting the rapid development of environmental quality criteria research in China. In 2017, the Ministry of Ecology and Environment of China (MEEC, formerly the Ministry of Environmental Protection of China) issued the technical guideline for deriving water quality criteria (WQC) for protection of freshwater organisms (HJ 831-2017), and in 2022, they organized the guideline revision and issued an updated version (HJ 831-2022). The primary contents of the revision included the following. The minimum toxicity data requirements were upgraded from 6 to 10, and the species mean toxicity value was replaced by the same effect toxicity value for the criteria calculation. It is now required that the tested organisms must be distributed in China's natural fresh waters, and the toxicity data of non-native model species will no longer be used. The list of freshwater invasive species in China that cannot be used as test species was added into the guideline. The acute/chronic ratio (ACR) method for the criteria derivation and the extreme value model were deleted, and the provisions for testing the toxicity data distribution were also deleted. The exposure time of the toxicity test of various tested organisms was refined, and the priority of the toxicity data was clearly specified. This paper introduces the framework and specific technical requirements of HJ 831-2022 in detail, including data collection, pre-processing of toxicity data, criteria derivation, fitting models, and quality control. This introduction is helpful for international peers to understand the latest research progress of China's WQC.

Reference dose prediction by using CDK molecular descriptors: A non-experimental method.

Reference dose (RfD) is an estimate of a daily dose that individual can be exposed chronically without obvious deleterious effects during a lifetime. In the area of toxicology, researchers always use the traditional approach by employing NOAEL/LOAEL or the benchmark dose (BMD) and other dose-response approaches to estimate RfD. These methods have, despite their typicalness, certain limitations. In this study, we present a novel method of the estimation of reference dose without experiments. The information of the organic chemicals is available from the Integrated Risk Information System (IRIS) of USEPA. Molecular descriptors for each molecular structure were calculated by an integrated platform, and the chemicals were classified into four categories based on molecular similarity: 128 contained benzene rings, 47 were heteroaromatics, 104 contained halogen substituents and 44 were halogenated aliphatic hydrocarbons. The predictive model of RfD was constructed by the multiple linear stepwise regression (MLR) method. Approximately 95% and 82% of the data points differ by less than 10-fold and 5-fold between the predicted values and the true values respectively. The non-experimental method improves the estimation efficiency and has a certain reference value to predict.

[Characteristics of Carbon and Nitrogen in the Downstream Columnar Sediment of Maozhou River, Shenzhen].

Based on the determinations of total nitrogen (TN), organic matter (OM), carbon-nitrogen ratio (C/N), δ15 N, and δ13 C on 12 sediment cores, the distribution characteristics and the sources of nitrogen and organic matter were analyzed in sediments from the lower reaches and main tributaries of the Maozhou River. The results showed that the average concentrations of total nitrogen (TN) and organic matter (OM) were 1815.37 mg·kg-1 and 22 401.68 mg·kg-1, respectively, in the Maozhou River sediments, which were higher than in TaihuLake and ChaohuLake. The levels of TN and OM in the study area were high and varied greatly with the increase of depth. The δ15 N content in the sediments of the MaozhouRiver downstream ranged from 2.20 ‰ to 32.78 ‰, while the δ13 C content ranged from -27.53 ‰ to -21.95 ‰. The average concentrations of δ15 N and δ13 C were 6.78 ‰ and -25.41 ‰. Moreover, the C/N ratio ranged from 0.49 to -18.23. The δ13 C varied slightly with the increase of depth, while δ15 N and C/N varied greatly. A source analysis in the study area indicated that C3 plants and chemical fertilizer were the main sources in the surface sediments (0-40 cm) downstream of the Maozhou River. Furthermore, algae were the main sources of organic matter in the deep sediments downstream of the Maozhou River and in tributary sediments of the Shajing River. Nitrogen in the surface sediments (0-40 cm) downstream of the Maozhou River mainly comes from inorganic fertilizer and soil organic nitrogen, while nitrogen in the Maozhou River deep sediments and Shajing River sediments mainly come from soil erosion and soil organic nitrogen.

[Difference of Species Sensitivities for Aquatic Life Criteria in China and the USA].

Recently, China has commenced water quality criteria (WQC) research using the species sensitivity distribution (SSD) method. However, it is difficult to obtain sufficient toxicity data on native species for thousands of contaminants. In this study, the feasibility of deriving aquatic life criteria using toxicity data from non-native species was analyzed (taking the USA as an example). Firstly, 10 pollutants [As(Ⅲ), Cr(Ⅵ), Hg, Cu, Pb, Zn, nitrobenzene, parathion, chlorpyrifos, tributyltin] with plenty of toxicity data (at least 3 Phyla and 8 Families) both in China and the USA were selected based on the recommended aquatic life criteria of 58 pollutants by the US EPA. Secondly, the two-sample Kolmogorov-Smirnov (K-S) test and comparison method of important points of HC5 and HC50 (hazardous concentrations for 5% of the species and 50% of the species) were used to determine the difference of species sensitivity between China and the USA. The result of two-sample K-S test showed that the difference of species sensitivity to Cu, chlorpyrifos and tributyltin between the two countries was significant (P<0.05). Additionally, there were significant differences for HC5 values [Cr(Ⅵ), chlorpyrifos] between the two countries, as well as the HC50 (chlorpyrifos). As a result, there were significant differences for the species sensitivity to some pollutants [Cr(Ⅵ), chlorpyrifos, etc.] between China and the USA. Therefore, in this situation, "over-protection" or "non-protection" may happen when using the criteria values or the toxicity data of American species directly to protect the Chinese native species.

[Measured and Predicted Aquatic Life Criteria and Risk Assessment of Chromium (VI) in Liaohe River].

In this study, toxicity data of aquatic species in Liaohe River for heavy metal chromium (VI) was collected and selected. The aquatic life criteria for chromium (VI) in Liaohe River was derived based on these toxicity data. Moreover, water samples of 25 sites in Liaohe River were collected, and the concentrations of chromium (VI) in these samples were analyzed. Finally, ecological risk assessment of chromium (VI) in Liaohe River was performed. Moreover, interspecies correlation estimation method (ICE) established by US EPA was used to predict the acute toxicity of species in Liaohe River, and aquatic life criteria based on predicted toxicity data was derived. The results showed that: the measured CMC (criteria maximum concentration), measured CCC (criteria continuous concentration) and the predicted CMC were 17. 73, 12. 15 and 13. 97 µg . L -1, respectively. Therefore, the ICE method could be used to predict the aquatic life criteria, because the predicted criteria value was very similar to the measured criteria value. Analysis of chromium (V) showed that the chromium (VI) concentrations of the 25 sites in Liaohe River were all below Class I or Class II water quality standards (GB 3838-2002), and the water quality was in good condition. However, for the potential risk of chromium (VI) exposure to the aquatic life of Liaohe River, the result of ecological risk assessment showed that chromium (V) concentrations in 7 sites exceeded the CCC in July, and chromium (VI) concentrations in 6 sites exceeded the CCC in December. Therefore, unacceptable effect on aquatic species caused by chromium (VI) exposure might have occurred in some sites of Liaohe River.

Development of water quality criteria for phenanthrene and comparison of the sensitivity between native and non-native species.

Phenanthrene (PHE) is a priority polycyclic aromatic hydrocarbon (PAH) which is toxic to aquatic organisms.However, there has been no paper dealing with water quality criteria (WQC) of PHE due to the shortage of toxicity data of different taxonomic levels. In the present study, toxicity data were obtained from 8 acute toxicity tests and 3 chronic toxicity tests using 8 Chinese native aquatic species from different taxonomic levels, and the water quality criteria was derived using 3 methods. Furthermore, differences of species sensitivity distributions (SSDs) between native and non-native species were compared. A criterion maximum concentration of 0.0514 mg/L and a criterion continuous concentration of 0.0186 mg/L were developed according to the US EPA guidelines. Finally, by using risk quotient (RQ) to assess the site-specific ecological risk in Liao River, the results indicated that the PHE might pose no risk to local aquatic species.

[Application of biotic ligand model for the acute toxicity of copper to Daphnia magna in water of Liaohe River and Taihu Lake].

The acute toxicity (48 h-LC50 ) of copper to Daphnia magna predicted by the biotic ligand model (BLM) was compared with the 48 h-LC50 measured in water samples from Liaohe River and Taihu Lake at four specific sites in wet and dry seasons. The results showed that 48 h-LC50 values predicted by BLM were 232.75-411.49 microgL-1 and 48 h-LC50 values measured in the water samples were 134. 55-350. 00 microg L-1 in three sites of Hongmiaozi of Liaohe River, Pingtaishan and Tuoshan of Taihu Lake, which had a better consistency. While for Tongjiangkou of Liaohe River, there was a difference between the BLM predictions and the measured values in wet and dry seasons. According to the predictions and the experimental results, water effect ratios (WERs) were in the range of 2. 18-5.79 and 1.88-11.15 which all were higher than 1. The acute toxicity of Cu of all sites in dry season was greater than those in wet season, which might be that Cu complexation with dissolved organic matter (DOC) reduced the toxicity of Cu.

[Species sensitivity evaluation of Pseudorasbora parva].

Acute toxic effects of cadmium and copper to Pseudorasbora parva and copper to Daphnia magna were tested in this study. Then comparative analysis of species sensitivity of P. parva to six typical pollutants was performed with toxicity data from our experiments and published literatures. The result showed that: (1) P. parva was generally sensitive to various pollutants, especially to organic pollutants, and it was relatively most sensitive to pesticides. P. parva might be an indicator organism in organic pollution monitoring and a representative testing organism in the development of water quality criteria. (2) Cyprinidae was sensitive to various pollutants in fish sensitivity distribution, therefore the toxicity data of Cyprinidae should be given more attention in the study of water quality criteria and environmental monitoring. (3) P. parva was sensitive to various pollutants, and it had a stable position in fish sensitivity rank. This study indicated that P. parva might be an ideal indicator organism in environmental monitoring and a potential model organism in water quality criteria considering that it has a small size and is easy to obtain.

Development of aquatic life criteria for triclosan and comparison of the sensitivity between native and non-native species.

Triclosan (TCS) is an antimicrobial agent which is used as a broad-spectrum bacteriostatic and found in personal care products, and due to this it is widely spread in the aquatic environment. However, there is no paper dealing with the aquatic life criteria of TCS, mainly result from the shortage of toxicity data of different taxonomic levels. In the present study, toxicity data were obtained from 9 acute toxicity tests and 3 chronic toxicity tests using 9 Chinese native aquatic species from different taxonomic levels, and the aquatic life criteria was derived using 3 methods. Furthermore, differences of species sensitivity distributions (SSD) between native and non-native species were compared. Among the tested species, demersal fish Misgurnus anguillicaudatus was the most sensitive species, and the fishes were more sensitive than the aquatic invertebrates of Annelid and insect, and the insect was the least sensitive species. The comparison showed that there was no significant difference between SSDs constructed from native and non-native taxa. Finally, a criterion maximum concentration of 0.009 mg/L and a criterion continuous concentration of 0.002 mg/L were developed based on different taxa, according to the U.S. Environmental Protection Agency guidelines.

[Tissue distribution and bioconcentration factors of tetrabromobisphenol A in five fishes in Lake Chaohu].

Tissue distribution and bioconcentration factors of tetrabromobisphenol A (TBBPA) in five economic fishes in Chaohu Lake were measured with SPE-HPLC. The results showed that, the average concentration of TBBPA was 4.70-11.20 ng x g(-1) (dry weight) in these fishes, in an order as White fish > Silver Carp > Bighead Carp > Common Carp > Longsnout Catfish. The highest concentration of TBBPA was found in the kidney, followed by liver and gill. The concentrations in fat and muscle were very low. Silver carp was really different from the other four fishes with the highest measured level in liver, followed by kidney and gills. In addition, the TBBPA concentration in tissues of the white fish showed positive correlation with the fish weight, especially in liver and kidney, but the trend is not significant in the back and belly tissues. The bioaccumulation factors of TBBPA for the 5 fishes were 9.56-22.64 based on the average concentration of TBBPA in water (0.52 microg x L(-1)) detected in this study, indicating insignificant bioconcentration effects of TBBPA on five fishes in Chaohu Lake.