Endocrine disrupting compounds in the middle and lower reaches of the Lhasa River Basin: Occurrence, distribution, and risk assessment

Spatial distribution, source identification, and potential risks of 14 bisphenol analogues in soil under different land uses in the megacity of Chengdu, China

This study explored the levels, distribution, potential sources, ecological risks and estrogenic activities of 14 bisphenol analogues (BPs) in soil under eight land-use types in the megacity of Chengdu, China. Eleven BPs were detected in the soil samples and the total concentrations ranged from 32.3 to 570 ng/g d.w. Levels of bisphenol BP (BPBP) in the soil (up to 208 ng/g d.w.) only second to the most dominant compound bisphenol A (BPA) were found. Relatively higher Σ14BP accumulation in the soil was observed in the commercial and residential areas (median: 136 ng/g d.w. and 131 ng/g d.w.) compared with agricultural area (median: 67.5 ng/g d.w.). Source identification indicated the role of atmospheric particulate deposition and consecutive anthropogenic activities in BP emission. The ecotoxicity assessment implied that BPA, bisphenol S (BPS), bisphenol F (BPF) and bisphenol PH (BPPH) might pose low to medium risk to the ecosystem due to their extensive use and biological effects. The calculated 17β-estradiol equivalents of BPs were in the range of 0.501-7.74 pg E2/g d.w, and the estrogenic activities were inferior to those contributed by natural estrogens in the soil.

Distribution, migration patterns, and food chain human health risks of endocrine-disrupting chemicals in water, sediments, and fish in the Xiangjiang River

Exposure to endocrine-disrupting chemicals (EDCs) in freshwater systems has garnered increasing attention. A comprehensive analysis of the migration patterns, bioaccumulation, and consumer health risk of EDCs along the Xiangjiang River due to fish consumption from the river ecosystem was provided. Twenty natural and synthetic target EDCs were detected and analyzed from the water, sediments, and fish samples collected along the Xiangjiang River. There were significant correlations between the EDC concentrations in fish and the sediments. This revealed that EDCs in sediments play a dominant role in the uptake of EDCs by fish. The bioaccumulation factor and biota-sediment accumulation factor were calculated, with the highest values observed for nonylphenol. Pearson's correlation analysis showed that bisphenol A is the most reliable biological indicator of EDC contamination in fish. Furthermore, based on the threshold of toxicological concerns and the health risk with dietary intake, crucian carp and catfish from the Xiangjiang River pose a certain risk for children and pregnant women compared to grass carp. The Monte Carlo simulation results indicated a certain risk of cumulative ∑EDC exposure for local residents due to fish consumption.

Invisible Hand behind Female Reproductive Disorders: Bisphenols, Recent Evidence and Future Perspectives

Reproductive disorders are considered a global health problem influenced by physiological, genetic, environmental, and lifestyle factors. The increased exposure to bisphenols, a chemical used in large quantities for the production of polycarbonate plastics, has raised concerns regarding health risks in humans, particularly their endocrine-disrupting effects on female reproductive health. To provide a basis for future research on environmental interference and reproductive health, we reviewed relevant studies on the exposure patterns and levels of bisphenols in environmental matrices and humans (including susceptible populations such as pregnant women and children). In addition, we focused on in vivo, in vitro, and epidemiological studies evaluating the effects of bisphenols on the female reproductive system (the uterus, ovaries, fallopian tubes, and vagina). The results indicate that bisphenols cause structural and functional damage to the female reproductive system by interfering with hormones; activating receptors; inducing oxidative stress, DNA damage, and carcinogenesis; and triggering epigenetic changes, with the damaging effects being intergenerational. Epidemiological studies support the association between bisphenols and diseases such as cancer of the female reproductive system, reproductive dysfunction, and miscarriage, which may negatively affect the establishment and maintenance of pregnancy. Altogether, this review provides a reference for assessing the adverse effects of bisphenols on female reproductive health.

Simple and cheap CRISPR/Cas12a biosensor based on plug-and-play of DNA aptamers for the detection of endocrine-disrupting compounds

Endocrine-disrupting compounds (EDCs) are widely distributed in the environment. Here, we present a CRISPR/Cas12a (CAS) biosensor based on DNA aptamers for point-of-care detection of EDCs. Two typical EDCs, 17β-estradiol (E2) and bisphenol A (BPA), were selected to be detected by the CAS biosensors via the plug-and-play of their DNA aptamers. The results indicated that the performance of the CAS biosensors can be well regulated by controlling the trans-cleavage activity of Cas12a on a single-stranded DNA reporter and optimizing the sequence and ratio of DNA aptamer and activator DNA. Ultimately, two reliable and specific biosensors were developed, with the linear range and limit of detection of 0.2-25 nM and 0.08 nM for E2 and of 0.1-250 nM and 0.06 nM for BPA, respectively. Compared to the existing detection methods, the CAS biosensors showed higher reliability and sensitivity with simple operation, short detection time, and no costly equipment.

Evaluating the spatial and temporal distribution of emerging contaminants in the Pearl River Basin for regulating purposes

Little information is available on how the types, concentrations, and distribution of chemicals have evolved over the years. The objective of the present study is therefore to review the spatial and temporal distribution profile of emerging contaminants with limited toxicology data in the pearl river basin over the years to build up the emerging contaminants database in this region for risk assessment and regulatory purposes. The result revealed that seven groups of emerging contaminants were abundant in this region, and many emerging contaminants had been detected at much higher concentrations before 2011. Specifically, antibiotics, phenolic compounds, and acidic pharmaceuticals were the most abundant emerging contaminants detected in the aquatic compartment, while phenolic compounds were of the most profound concern in soil. Flame retardants and plastics were the most frequently studied chemicals in organisms. The abundance of the field concentrations and frequencies varied considerably over the years, and currently available data can hardly be used for regulation purposes. It is suggested that watershed management should establish a regular monitoring scheme and comprehensive database to monitor the distribution of emerging contaminants considering the highly condensed population in this region. The priority monitoring list should be formed in consideration of historical abundance, potential toxic effects of emerging contaminants as well as the distribution of heavily polluting industries in the region.

Distribution and source apportionment of phenolic EDCs in rivers in the Pearl River Delta, South China

The sources and distribution characteristics of three phenolic endocrine-disrupting compounds (EDCs), e.g., alkylphenols (APs) (including nonylphenols (NPs) and 4-t-octylphenol (OP)) and Bisphenol A (BPA), were investigated in the rivers of the Pearl River Delta Region (PRDR) with complex land-use types. The mean concentrations of NPs, OP, and BPA in river water including wet and dry seasons were 87, 6, and 74 ng/L in the agricultural regions (n = 10), 135, 7, and 61 ng/L in the transitional regions (n = 8), and 249, 15, and 152 ng/L in the urban regions (n = 28). Contents of NPs and BPA were high in the river sediments (ranged from 7 to 3048 ng/g and 2 to 271 ng/g, respectively). Equilibrium analysis results suggested that sediment release was not the main source of the river EDCs. Principal component analysis (PCA) showed that sewage was the major source of EDCs in the dry season, while the leaching effect of rainfall on the agricultural soils, urban roads, and commercial products was an important source in the wet season. Furthermore, the ratio of APs and total concentration of phenolic EDCs (ΣEDCs) was used to characterize the agricultural regions and urban regions in the PRDR. The ratio was less than 0.6 in the agricultural regions while the ratio was large than 0.6 in the dry season and less than 0.6 in the wet season in urban regions. BPA and NPs in transitional region and urban region had small/medium potential risk to aquatic organisms.

Occurrence, spatial distribution, and potential risks of organic micropollutants in urban surface waters from qinghai, northwest China

Lack of knowledge on the destiny of organic micropollutants (OMPs) in the Tibetan Plateau region of China prevents the public from being aware of the need for protecting these unique aquatic ecosystems that are precious water resources and source areas of the Yellow River. To address this knowledge gap, this study systematically investigated the multi-residue analysis, distribution, and potential risks of six types of OMPs, namely, neonicotinoid pesticides (NEOs), fungicides, organophosphate esters (OPEs), organophosphorus pesticides (OPPs), psychoactive substances (PSs), and antidepressants (ADs), in surface waters of major cities in Qinghai. A total of 31 compounds, consisting of 8 NEOs, 1 fungicide, 12 OPEs, 2 OPPs, 5 PSs, and 3 ADs, were detected in >50% of the sites, showing their ubiquitous nature in the study area. Results showed that the total OMP concentration in surface water was 28.3-908 ng/L, and OPEs were the dominant composition (48.6%-97.4%). The risk quotient values of the detected diazinon and dursban regularly exceeded 1 for aquatic organisms at all sampling sites, indicating moderate-high chronic ecological risk. The joint probability curves showed that dursban and NEOs have higher risk levels than other OMPs. Although the results of the non-carcinogenic total hazard quotient of the OMPs in the surface water was less than 1 in all age groups and the carcinogenic risk was lower than the negligible risk level, the potential risks to children and infants were considerably greater and should not be underestimated. In addition to pollutant concentration and exposure duration, ingestion rate and body weight (BW) are also important factors affecting health risk, with BW having a negative effect. To the best of the authors' knowledge, this report is the first to describe OMP pollution in Qinghai, and the results provide new insight into the ecological security of the water resources of the Tibetan Plateau.

Bisphenol analogues in water and sediment from the Beibu Gulf, South China Sea: Occurrence, partitioning and risk assessment

Bisphenol analogues (BPs) have gained increasing attention in recent years due to their ubiquitousness in the environment, potential endocrine disrupting properties and ecological impacts. However, very little information is available on the occurrence, partitioning and ecological risks of BPs in marine environments. In the present study, six BPs were investigated in surface water and sediment samples from the Beibu Gulf, South China Sea. Results showed that bisphenol A (BPA) was the predominant BP in both water and sediment samples with levels ranging from 5.26 to 12.04 ng/L in water and 0.56 to 5.22 ng/g dw in sediment samples, followed by bisphenol AF (BPAF: 0.44-0.60 ng/L in water and 0.08-0.66 ng/g dw in sediment samples, respectively) and bisphenol S (BPS: 0.07-0.63 ng/L in water and not detected (ND) to 0.19 ng/g dw in sediment samples, respectively). There is no significant spatial difference of BPs levels between riverine sediment samples and coastal sediment samples. Compared with other studies, the concentrations of BPs from the Beibu Gulf were relatively low. The mean log-transformed sediment-seawater partitioning coefficients (log K_oc) ranged from 4.4 (DHBP) to 5.2 (BPAF) and the log K_oc values for all the target BPs were generally higher than those reported in freshwater environments. The present study firstly reported the field-based log K_oc values for BPB (mean: 4.5) and DHBP (mean: 4.4). The estimated risk quotient (RQ) and 17β-estradiol (E2) equivalent quotient (EEQ) values indicated that the ecological and human health impacts were negligible associated with target BPs. The present study provided reliable and detailed data for completely evaluating contamination level and environmental behaviors of BPs in the Beibu Gulf.

Exploration of the effect of simultaneous removal of EDCs in the treatment process of different types of wastewater

The SPE-HPLC-MS/MS method was used to investigate the concentration distribution of nine types of estrogens in 18 locations of pollution source along the Jiuzhou River belonging to river systems in Guangdong province and Guangxi Zhuang autonomous region in China, and the estrogenic activity and potential ecological risks were evaluated by calculating the estradiol equivalency (EEQ). The results showed that the calculated estradiol equivalents (cEEQs) of wastewater treatment plants from 17 locations were all higher than 1 ng/L. To further study the removal effect of the treatment process on the estrogens, the pig breeding wastewater from P4 and the municipal wastewater from P13, as well as the black-odorous water, were sampled and surveyed during the entire process. It turned out that estrogens were effectively removed after nitrification activated sludge treatment. Meanwhile, there was a positive correlation between the removal of NH₃-N, total nitrogen (TN) and total phosphorus (TP) and the removal of endocrine disrupting chemicals (EDCs). It is shown in the study the secondary treatment process has achieved a significant effect on the removal of estrogen in both the wet and dry periods and that there has been a positive correlation between the activities of total phosphorus compounds, nitrogen-based compounds and the removal of EDCs.

Nitrogen loadings affect trophic structure in stream food webs on the Tibetan Plateau, China

Anthropogenic activities, such as agricultural and industrial development, have increased nutrient inputs into waterways, which affect trophic interactions and the flow of energy through food webs in the aquatic ecosystems. However, the responses of food web structure and function to specific anthropogenic stressors in the alpine stream systems remain unclear. Here, we studied the stream food webs in the Lhasa River on the Tibetan Plateau, China. We measured the isotopic ratios (δ¹³C and δ¹⁵N) of macroinvertebrate and fish functional feeding groups (FFGs) and their basal resources in the streams. Dietary contributions of basal resources to consumers and food web metrics including trophic length, diversity, and redundancy were used to quantify changes in stream food webs in response to anthropogenic disturbance. Dietary analysis showed that allochthonous resources contributed more than autochthonous resources to macroinvertebrate primary consumers regardless of the disturbance intensity in the adjacent land areas. Anthropogenic activities increased the δ¹⁵N values in epilithic algae and isotopic variation in basal resources and fish but reduced the trophic length and redundancy (i.e., fewer species or taxon at each trophic level) in food webs. Additionally, the total nitrogen concentration in waters was the most important environmental variable affecting trophic diversity and redundancy. Therefore, the reduction of nitrogen inputs into streams is critical for sustainable river management and biodiversity conservation in the streams on the Tibetan Plateau.

The strategy for estrogen receptor mediated-risk assessment in environmental water: A combination of species sensitivity distributions and in silico approaches

Risk assessment for molecular toxicity endpoints of environmental matrices may be a pressing issue. Here, we combined chemical analysis with species sensitivity distributions (SSD) and in silico docking for multi-species estrogen receptor mediated-risk assessment in water from Dongjiang River, China. The water contains high levels of phenolic endocrine-disrupting chemicals (PEDCs) and phthalic acid esters (PAEs). The concentration of ∑₄PEDCs and ∑₆PAEs ranged from 2202 to 3404 ng/L and 834-4368 ng/L, with an average of 3241 and 2215 ng/L, respectively. The SSD approach showed that 4-NP, BPA, E2 of PEDCs, and DBP, DOP, and DEHP could severely threaten the aquatic ecosystems, while most other target compounds posed low-to-medium risks. Moreover, binding affinities from molecular docking among PEDCs, PAEs, and estrogen receptors (ERα, Erβ, and GPER) were applied as toxic equivalency factors. Estrogen receptor-mediated risk suggested that PEDCs were the main contributors, containing 53.37-69.79% of total risk. They potentially pose more severe estrogen-receptor toxicity to zebrafish, turtles, and frogs. ERβ was the major contributor, followed by ERα and GPER. This study is the first attempt to assess the estrogen receptor-mediated risk of river water in multiple aquatic organisms. The in silico simulation approach could complement toxic effect evaluations in molecular endpoints.

Occurrence, distribution, and ecological risk of psychoactive substances in typical lakes and rivers in Qinghai-Tibet Plateau

The occurrence, distribution, and ecological risks of psychoactive substances (PSs) in Qinghai-Tibet Plateau (QTP) was investigated in this study. The surface water samples were collected in July in 2020 from five major water bodies, and 9 PSs were determined by liquid chromatography-mass spectrometry. The mean concentrations of the total PSs were 2.19-96.86 ng/L in lakes and 4.56-34.47 ng/L in rivers. Amphetamine (AMP) was the predominant contaminant both in lakes and rivers with a mean concentration of 12.21 ± 22.76 ng/L and 9.83 ± 6.14 ng/L, respectively. The compositions of PSs in lakes and rivers were significantly different. AMP, methadone (MTD), 3,4-methylenedioxyamphetamine (MDA), and ketamine (KET) were the most detected contaminants in lakes, while in rivers AMP, MDA, heroin (HER), and methamphetamine (METH) were the most detected ones. Concentrations of AMP and MTD, the two predominant drugs, varied spatially, with the decreasing concentration of AMP in the order of Huangshui River > Yamzhog Yumco Lake > Qinghai Lake > Lhasa River > Namco Lake, and of MTD in the order of Qinghai Lake > Namco Lake > Huangshui River > Yamzhog Yumco Lake. The risk quotients (RQs) of PSs ranged from 4.44 × 10^-6 to 4.32 × 10^-2, indicating a low risk of PSs in the aquatic ecosystem in QTP. Compared with other research in the world, the contamination of psychoactive substances in the Qinghai-Tibet Plateau was at relatively low levels with low ecological risks.

Key role of suspended particulate matter in assessing fate and risk of endocrine disrupting compounds in a complex river-lake system

Endocrine-disrupting compounds (EDCs) enter lakes mainly through river inflow. However, the occurrence, transport and fate of EDCs in the overlying water, suspended particulate matter (SPM) and sediment of inflowing rivers remain unclear. This study investigated the load of seven EDCs in a complex river-lake system of the Taihu Lake Basin during different seasons, with the aims of revealing the transport routes of EDCs and identifying the contributions from different sources. The results indicated that the levels of the seven EDCs in the wet season with high temperature and dilution effects were generally lower than those in the other seasons. EDC enrichment in the sediment was largely affected by the transport and fate of SPM. Moreover, the estrogenic activity and risks of EDCs were the highest in SPM. The mass loadings of particulate EDCs carried by SPM were 2.6 times that of overlying water. SPM plays a vital role in the transport and fate of EDCs in complex river-lake systems and thereby deserves more attention. Nonpoint sources, particularly animal husbandry activities and untreated domestic sewage, were the main sources of EDCs, amounting to 61.5% of the total load.

Occurrence, spatial distribution, and main source identification of ten bisphenol analogues in the dry season of the Pearl River, South China

Bisphenol analogues (BPs) including bisphenol a (BPA) have been broadly utilized as industrial feedstocks and unavoidably discharged into water bodies. However, there is little published data on the occurrence, distribution, and environmental risks of other BPs in surface water. In this study, ten BPs besides BPA were analyzed in surface water from the Pearl River, South China. Among these detected BPs, BPA, bisphenol F (BPF), bisphenol AF (BPAF), and bisphenol S (BPS) were the most frequently detected compounds. The median concentrations of the measured BPs were ranked in the order of BPA (34.9 ng/L) > BPS (24.8 ng/L) > BPAF (10.1 ng/L) > bisphenol F (BPF) (9.0 ng/L) > bisphenol B (BPB) (7.6 ng/L) > bisphenol C (BPC) (1.2 ng/L). Among them, BPA and BPS were predominant BPs, contributing 68% of the total ten BPs in surface water of the Pearl River. These results demonstrated that BPA and BPS were the most extensively utilized and manufactured BPs in this region. The source analysis of BPs suggested that the BPs may be originated from domestic wastewater, wastewater treatment plant (WWTP) effluent, and the leaching of microplastic in surface water of the Pearl River. The calculated BP-derived estrogenic activity exhibited low to medium risks in surface water, but their combined estrogenic effects with other endocrine disrupting compounds should not be ignored.

Pollution Characteristics and Risk Prediction of Endocrine Disruptors in Lakes of Wuhan

As a new and ubiquitous trace organic pollutant, endocrine-disrupting compounds (EDCs) can cause endocrine-disrupting effects on organisms even at low levels. However, little information is available on the resource and assessment of EDC risks in the water environment. The study area was selected based on the paucity of information on the pollution status of inland lakes. Wuhan has numerous and diverse types of lakes which receive micropollutants from different pathways. In this study, the spatial distribution, occurrence, quantity and ecological risks of EDCs in 12 lakes were investigated. Five EDCs, including 17-alpha-ethinylestradiol (17α-EE₂), estrone (E₁), β-estradiol (β-E₂), estriol (E₃) and bisphenol A (BPA) were detected in surface waters. The distribution of EDC content in the lakes was ordered as follows: exurban zone < suburban area < urban areas. The pollution sources in remote lakes mainly included agricultural and aquaculture wastewater, while those in suburban and urban areas included domestic or industrial wastewater. Areas with higher EDC content were frequently related to agricultural activities, aquaculture water or dense populations. Water quality parameters, including dissolved oxygen, pH and water temperature, were significantly related to the occurrence and distribution of EDCs in the lakes. Risk assessment demonstrated that the occurrence of EDCs posed minimum to medium risk to aquatic organisms in the lakes. The results showed that the lakes faced a threat hormone pollution though it was at lower doses and, thus, the ecological risk of EDCs should be considered in future environmental policies and decisions in China.

Contamination and ecological risks of steroid metabolites require more attention in the environment: Evidence from the fishing ports

Due to strong endocrine disrupting effects, steroids in the environment have attracted substantial attention, with studies mostly focusing on the parent steroids. Here, we conducted the first investigation on the contamination profiles, possible sources, mass inventories, and ecological risks of 27 steroids and their metabolites in 15 typical fishing ports in Southeast China. Twelve steroids were detectable in the sediment samples with the total mean concentrations of 4.6-35 ng/g. High proportions of steroid metabolites were measured in the sediments and five metabolites were newly observed. Untreated municipal sewage and aquaculture wastes constitute the possible steroid sources in the studied fishing ports. The total inventories of steroids in fishing ports ranged from 2.1-16 mg/m², with their metabolites being important contributors. The ecological risk analysis indicated high risks across all sampling sites mainly due to the contributions of parent steroids. Furthermore, our results found that progesterone is an acceptable chemical indicator for various steroids in sediments. This study provides the first evidence of steroid metabolites in the marine environment, calling for more studies in environmental behavior and ecotoxicology of steroid metabolites.

Distribution and Estrogenic Risk of Alkylphenolic Compounds, Hormones and Drugs Contained in Water and Natural Surface Sediments, Morelos, Mexico

This study evaluated the distribution and potential estrogenic risk of the presence of bisphenol A (BPA), 4-nonylphenol (4NP), naproxen (NPX), ibuprofen (IBU), 17-β-estradiol (E2) and 17-α-ethinylestradiol (EE2) in water and sediments of the Apatlaco river micro-basin (Morelos, Mexico). The concentration of the determined compounds ranged between <LOD to 86.40 ng·L−1 and <LOD to 3.97 ng g−1 in water and sediments, respectively. The Log Kd distribution obtained (from 1.05 to 1.91 L Kg−1) indicates that the compounds tend to be adsorbed in sediments, which is probably due to the hydrophobic interactions confirmed by the significant correlations determined mainly between the concentrations and parameters of total organic carbon (TOC), total suspended solids (TSS), biological oxygen demand (BOD5) and chemical oxygen demand (COD). Of five sites analyzed, four presented estrogenic risk due to the analyzed endocrine-disrupting compounds (EEQE2 > 1 ng·L−1).

Occurrence, distribution, and risk assessment of bisphenol analogues in Luoma Lake and its inflow rivers in Jiangsu Province, China

Bisphenol analogs (BPs) are widely used in industrial and commercial products and have been detected in surface water, sediment, sewage, and sludge. The presence of BPs in the natural environment poses threats to the aquatic ecosystem and human health. The concentration, distribution, seasonal variation, and risk assessment of BPA and BPA structural analogs including BPB, BPF, BPS, BPZ, BPAF, and BPAP in surface water and sediment during dry season and flood season in Luoma Lake and its inflow rivers in Jiangsu Province, China, were investigated in this study. The detection frequency of BPA and BPF was 100%. Although the use of BPA is restricted, BPA is still the dominant BPs in surface water and sediment. The concentration of BPs in surface water during flood season was higher than that in dry season. The concentrations of BPs in Fangting River, Zhongyun River, and Bulao River were higher than those in Luoma Lake. The average concentrations of BPs in surface water were in the order of BPA > BPF> BPS> BPB > BPZ > BPAF> BPAP. Compared with other studies, the concentration of BPs in Luoma Lake was moderate. There is no significant spatial distribution and difference in seasonal variation of BPs concentration in sediment (p > 0.05). Compared with other studies, the contamination of BPs in sediment of Luoma Lake was relatively low. Risk quotient (RQ) was used to evaluate the ecological risk of BPs in water environment, and the 17β estradiol equivalent (EEQ) method was used to estimate the estrogenic activity of BPs. The risk assessment showed no high ecological risk (RQ < 1.0) and estrogenic risk (EEQ < 1.0 ng/L) in dry season and flood season. The estimated RQ and EEQ_t indicated that the ecological and human health impacts were negligible in the short term.

Anthropogenic disturbances on antibiotic resistome along the Yarlung Tsangpo River on the Tibetan Plateau: Ecological dissemination mechanisms of antibiotic resistance genes to bacterial pathogens

Human activities can accelerate the antibiotic resistome prevalence and pose threats to ecological safety and public health globally. However, antibiotic resistance gene (ARG) mobility and dissemination into bacterial pathogens under anthropogenic disturbances are still poorly understood. Here, we used a metagenomic approach to profile the biogeography of ARGs and pathogenic antibiotic resistant bacteria (PARB) under anthropogenic disturbances along the Yarlung Tsangpo River. Results showed the ARGs was dominated by bacA gene along the Yarlung Tsangpo River on the Tibetan Plateau. The ARG composition was differently impacted by rapid urbanization and dam construction, which urbanization could promote ARGs resistant to sulfonamide and tetracycline, whereas dam construction could elevate the resistance to chloramphenicol and aminoglycoside. Land use pattern was identified as a critical factor influencing ARG composition under anthropogenic disturbances, as it could directly reflect the land degradation level and indicate the inputs of ARG-selective chemicals of different human activities. Moreover, despite of the lack of variation in ARG relative abundance, PARB were highly promoted by anthropogenic activities, indicating increasing ARG dissemination to pathogen. We found that human-impacted environments harbored high proportion of mobile genetic elements (MGEs), and the MGE carrying ARGs also increased under anthropogenic disturbances in the pathogenic hosts, which confirmed that anthropogenic activities could promote ARG horizontal gene transfer. Furthermore, anthropogenic activities could influence PARB assembly processes. Basically, stochastic processes dominated PARB assembly along the river, and with increasing level of anthropogenic activities, these processes shifted from undominated stochastic processes to dispersal limitation. In summary, this study provides useful strategies in watershed resistome management and reduction of ARG dissemination to pathogens, which should consider the mode and intensity of human activity and its potential influence on horizontal gene transfer and assembly processes.

Secondary treatment phase of tertiary wastewater treatment works significantly reduces estrogenic load

Estrogenic compounds enter waterways via effluents from wastewater treatment works (WWTW), thereby indicating a potential risk to organisms inhabiting adjacent receiving waters. However, little is known about the loads or concentrations of estrogenic compounds that enter Australian WWTWs, the efficiency of removing estrogenic compounds throughout the various stages of tertiary WWTW processes (which are common in Australia), nor the concentrations released into estuarine or marine receiving waters, and the associated risk for aquatic taxa residing in these environments. Therefore, seven estrogenic compounds, comprising the natural estrogens estrone (E1), 17β-estradiol (E2) and estriol (E3), the synthetic estrogen (EE2), and the industrial chemicals bisphenol A (BPA), 4-t-octyl phenol (4-t-OP) and 4-nonyl phenol (4-NP), in wastewater samples were quantified via liquid chromatographic-mass spectrometry (LC-MS) after solid-phase extraction at different stages of wastewater treatment and associated receiving waters. The concentrations of the target compounds in wastewater ranged from < LOQ (limit of quantification) to 158 ng/L for Tanilba Bay WWTW and < LOQ to 162 ng/L for Belmont WWTW. Most target compounds significantly declined after the secondary treatment phase. Appreciable removal efficiency throughout the treatment process was observed with removal from 39.21 to 99.98% of influent values at both WWTWs. The reduction of the natural estrogens (E1, E2 and E3) and 4-t-OP were significantly greater than EE2, BPA, and 4-NP in both WWTWs. Risk quotients (RQs) were calculated to assess potential ecological risks from individual estrogenic compounds. In predicted diluted effluents, no targeted compounds showed any ecological risk (RQ ≤1.65 × 10^-2) at both WWTWs. Similarly, all RQs for shore samples at both WWTWs were below 1. Finally, the hazard index (HI), which represents combined estrogenic contaminants' ecological risk, indicated no mentionable risk for predicted diluted effluents (HI = 0.0097 to 0.0218) as well as shoreline samples (HI = 0.393 to 0.522) in the receiving estuarine or marine waters.

Fungal laccase-triggered 17β-estradiol humification kinetics and mechanisms in the presence of humic precursors

Naturally-occurring phenolic acids (PAs) act as humic precursors that participate in the conversion behaviors and coupling pathways of steroidal estrogens (SEs) during laccase-triggered humification processes (L-THPs). Herein, the influences and mechanisms of PAs on Trametes versicolor laccase-evoked 17β-estradiol (E2) conversion kinetics and humification routes were explored. Fungal laccase was fleet in converting > 99% of E2, and the calculated pseudo-first-order velocity constant and half-time values were respectively 0.039 min^-1 and 17.906 min. PAs containing an O-dihydroxy moiety such as gallic acid and caffeic acid evidently hampered E2 humification owning to the yielded highly reactive O-quinones reversed E2 radicals by hydrogen transfer mechanism, implying that the inhibition effect was enormously dependent upon the number and position of the phenolic -OH present in humic precursors. Oligomers and polymers with carbon-carbon/oxygen links were tentatively found as E2 main humified species resulting from laccase-evoked successive oxidative-coupling. Note that PAs participating in the humification also encountered oxydehydrogenation, self-polymerization, and cross-binding to E2. Interestingly, the -COOH and -OCH₃ groups of PAs could be deprived in radical-caused self/co-polymerization. The generation of humified products not only circumvented the environmental risks of parent compounds but accelerated global carbon sequestration. To our knowledge, this is the first in-depth revelation of the humification pathways and related mechanisms of SEs with humic precursors in aquatic ecosystems by L-THPs.