Implications on freshwater lake-river ecosystem protection suggested by organic micropollutant (OMP) priority list

Spatiotemporal distribution and priority assessment of steroids in the estuarine environment: Implications for environmental risk management

Steroids, known for their endocrine-disrupting capabilities, have become a subject of considerable concern in the scientific community. This research offers a thorough evaluation of steroid contaminants within the Jiulong River Estuary (JRE), examining their spatiotemporal distribution, multimedia distribution, and mass inventory. Seven steroids were detected in water samples, while ten steroids were identified in sediments, with concentrations ranging from 0.2 to 51 ng/L in water and no-detectable (ND) to 12 ng g-1 in sediments. In both water and sediments, natural steroids were the most prevalent throughout both the dry and wet seasons. The distribution of these compounds within the aquatic-sediment system was governed by their hydrophobicity and a suite of environmental factors, such as temperature, salinity, pH, chlorophyll-a, and total organic carbon content. Mass inventory analysis revealed that over 90 % of the total steroid mass inventory was stored in the sediments, underscoring their pivotal role as a repository for these substances within the JRE. Furthermore, this research represents the first comprehensive screening to identify priority contaminants in this region. Utilizing a multi-metric evaluation approach, progesterone and testosterone were identified as high-priority pollutants during the dry season, with progesterone alone ranking as a high-priority pollutant in the wet season. This study provides crucial insights for the management of steroid-related pollution and the assessment of environmental risks in estuarine ecosystems.

A comprehensive reconnaissance and risk assessment of rubber additives and their transformation products (RATPs) in groundwater: 1,3-Diphenylguanidine (DPG) as a pressing ecological concern

The widespread detection of rubber additives and their transformation products (RATPs) in surface water environments is well-documented, but their pollution characteristics in groundwater remain unclear. This study comprehensively revealed the occurrence and distribution of 27 RATPs in groundwater across southern China (n = 212). RATPs were detected in groundwater at total levels of 1.21-2,345 ng/L. The primary compounds detected were 1,3-Diphenylguanidine (DPG), 1,3-diphenylurea (DPU), and 2-hydroxybenzothiazole (2-OH-BTH), each with a detection frequency of 99.5 % and mean concentrations of 125, 58.4, and 51.2 ng/L, respectively. The spatial distribution of RATPs in groundwater shows significant lateral variations but lacks vertical differences. Correlation analysis indicates a strong relationship between the RATPs pollution levels and both the type of groundwater and the level of urban economic development, with karst water exhibiting particularly high pollution levels. Five RATPs exhibited medium to high ecological risks in groundwater. The daily intake of RATPs via groundwater in South China is 3.61 × 10-8-7.00 × 10-5 mg/(kg·d). According to the multicriteria evaluation approach and persistence, mobility, and toxicity (PMT) assessment, six RATPs, including DPG, have been identified as high-priority pollutants that require significant attention in groundwater management. This study highlights the contamination characteristics and ecological risks associated with RATPs in groundwater, emphasizing the need for increased focus on these widely used yet inadequately evaluated chemicals in future research.

Pesticide dynamics and risk assessment in a plateau lake: Multiphase partitioning, drivers, and distribution in Southwestern China

Erhai Lake, a vital drinking water source for Dali, a highland agricultural city, faces potential contamination from pesticide residues, yet limited studies have assessed their distribution and impacts. This study investigates the occurrence, transport, partitioning, and ecological risks of pesticides in the lake's dissolved phase (DP), suspended particulate matter (SPM), and sediment (SD) samples collected from 22 sites across different seasons. The results showed significant temporal variations across different media, with spatial variations driven by crop-related patterns. Atrazine, etridiazole, and cis-permethrin were identified as the most abundant pesticides in DP, SPM, and SD, respectively. Notably, the source-sink dynamics were not only driven by deposition and resuspension but influenced by multiple sources and hydrodynamic processes such as precipitation, phytoplankton biomass, organic carbon, and winds. Ecotoxicological assessments indicated that permethrin, endrin, and endosulfan sulfate posed significant ecological risks to aquatic organisms. Although human health risks from pesticides were low, ongoing monitoring of atrazine is recommended due to its extensive use around Dali City.

Polycyclic aromatic hydrocarbons (PAHs) occurrences in water bodies, extraction techniques, detection methods, and standardized guidelines for PAHs in aqueous solutions

Polycyclic aromatic hydrocarbons (PAHs) are a carcinogenic compound comprised of benzene ring(s). They occur naturally. However, the occurrence of anthropogenic PAHs (originates from human activities and man-made structures) may contribute to water pollution, risking the public health and aquatic life. This review describes occurrences of PAHs in water bodies, extraction techniques, detection methods, and standardized guidelines for PAHs in aqueous solutions. Previous research identifies PAH contamination across freshwater bodies due to proximity to pollution sources and hydrological factors. Despite analytical advancements, accurately quantifying and characterizing PAHs in complex environmental matrices remains challenging. Overall, this review supports the Sustainable Development Goals (SDGs) no. 6 (clean water and sanitation public) and no. 14 life below water.

Rejection of an emerging small neutral organic micropollutant by in-situ nanofiltration membrane modification for water treatment

Nanofiltration (NF) membranes are recognized for their potential in removing organic micropollutants (OMPs). However, the limited efficiency of commercial NF membranes in removing small and neutral emerging OMPs has impeded its wide use. This study explores the effectiveness of in-situ modification of commercial NF270 membranes using two monomers for the removal of 1H-benzotriazole (BTA). For the first time, this work investigates the physicochemical properties of commercial NF270 membranes grafted with these two monomers, 3-(trimethoxysilyl)propyl methacrylate and 2-(diethylamino)ethyl methacrylate, using different surface characterization techniques. The study also evaluates the performance of both unmodified and modified membranes in the rejection of BTA and compares the results with state-of-the-art monomers. The 2-(diethylamino)ethyl methacrylate-grafted membranes show a modest enhancement of 12 % in BTA rejection. In contrast, the 3-(trimethoxysilyl)propyl methacrylate-modified membranes exhibit a remarkable 107 % improvement in BTA rejection compared to the virgin NF270 membrane, achieving the highest increase in OMP removal among current state-of-the-art monomer-modified membranes reported in previous research. This approach effectively removes BTA primarily through the mechanisms of size exclusion and hydrophobic interactions. This research presents a comprehensive strategy for surface modification of NF membranes, offering potential improvements in the rejection of small and neutral OMPs for water treatment.

Sequential carbonization of pig manure biogas residue into engineered biochar for diethyl phthalate removal toward environmental sustainability

Manure biogas residue has attracted increasing attention in waste recycling but faces substantial challenges because of its low carbon content, high ash content, and high heavy metal content. A novel sequential carbonization approach was proposed for recycling biogas residue; this approach consisted of pre-pyrolysis, activation with Ca(OH)2, and then activation with KOH. Pig manure-derived biogas residue was upcycled into engineered biochar (EB) with a high yield (26 %) and showed excellent performance in removing a typical plasticizer, diethyl phthalate (DEP). The proportion of carbon content greatly increased from 18 % (biogas residue) to 67 % (EB); however, the ash content decreased from 50 % (biogas residue) to 24 % (EB). The concentration of heavy metals decreased, and Zn had the largest decrease from 713 mg kg-1 to 61 mg kg-1 (p < 0.001). The sorption of DEP onto EB was rapid and reached equilibrium within 20 h. The developed specific surface area of EB was 1247 m2/g and provided abundant sorption sites for DEP; additionally, the sorption quantity reached 309 mg/g. The sorption capacity was dominated by surface adsorption. The oxygen-containing functional groups, graphene structure, porous structure, and hydrophobicity of EB contributed to the pore filling, hydrogen bonding, π-π stacking, and partitioning processes. Furthermore, the EB showed excellent practical application potential and great cycling stability. A sequential carbonization strategy was proposed to upcycle manure biogas residue into the EB for DEP removal; moreover, this strategy can aid in the attainment of environmental sustainability, including sustainable waste management and environmental pollution mitigation.

Unveiling spatiotemporal distribution, partitioning, and transport mechanisms of tire additives and their transformation products in a highly urbanized estuarine region

Numerous tire additives are high-production volume chemicals that are used extensively worldwide. However, their presence and partitioning behavior remain largely unknown, particularly in marine environments. This study is the first to reveal the spatiotemporal distribution, multimedia partitioning, and transport processing of 22 tire additives and their transformation products (TATPs) in a highly urbanized estuary (n = 166). Nineteen, 18, and 20 TATPs were detectable in water, suspended particulate matter (SPM), and sediments, respectively, with total levels of 59.7-2021 ng/L, 164-6935 ng/g, and 4.66-58.4 ng/g, respectively. The multimedia partitioning mechanisms of TATPs are governed by their molecular weight, hydrophobicity, and biodegradation rate. Mass inventories coupled with model simulations have revealed that substantial quantities of TATPs accumulate within estuarine environments, and these compounds can be continuously transported into the ocean, particularly during the wet season. According to the multi-criteria evaluation approach, four and three TATPs were identified as high-priority pollutants during the dry and wet seasons, respectively. Unexpectedly, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone was only listed as a medium-priority pollutant. This study underscores the importance of marine surveillance and advocates for particular attention to these ubiquitous but underexplored TATPs in future studies.

First Report on the Trophic Transfer and Priority List of Liquid Crystal Monomers in the Pearl River Estuary

Liquid crystal monomers (LCMs) are emerging organic pollutants due to their potential persistence, toxicity, and bioaccumulation. This study first characterized the levels and compositions of 19 LCMs in organisms in the Pearl River Estuary (PRE), estimated their bioaccumulation and trophic transfer potential, and identified priority contaminants. LCMs were generally accumulated in organisms from sediment, and the LCM concentrations in all organisms ranged from 32.35 to 1367 ng/g lipid weight. The main LCMs in organisms were biphenyls and analogues (BAs) (76.6%), followed by cyanobiphenyls and analogues (CBAs) (15.1%), and the least were fluorinated biphenyls and analogues (FBAs) (11.2%). The most abundant LCM monomers of BAs, FBAs, and CBAs in LCMs in organisms were 1-(4-propylcyclohexyl)-4-vinylcyclohexane (15.1%), 1-ethoxy-2,3-difluoro-4-(4-(4-propylcyclohexyl) cyclohexyl) benzene (EDPBB, 10.1%), and 4'-propoxy-4-biphenylcarbonitrile (5.1%), respectively. The niche studies indicated that the PRE food web was composed of terrestrial-based diet and marine food chains. Most LCMs exhibited biodilution in the terrestrial-based diet and marine food chains, except for EDPBB and 4,4'-bis(4-propylcyclohexyl) biphenyl (BPCHB). The hydrophobicity, position of fluorine substitution of LCMs, and biological habits may be important factors affecting the bioaccumulation and trophic transfer of LCMs. BPCHB, 1-(prop-1-enyl)-4-(4-propylcyclohexyl) cyclohexane, and EDPBB were characterized as priority contaminants. This study first reports the trophic transfer processes and mechanisms of LCMs and the biomonitoring in PRE.

Season and side-chain length affect the occurrences and behaviors of phthalic acid esters in wastewater treatment plants

Emerging pollutants (EPs) are prevalent in aquatic environments globally. Researchers strive to understand their occurrence and behavior prior to their release into the environment. In this study, we examined five wastewater treatment plants (WWTPs), collected 50 wastewater samples and 10 sludge samples. We explored the sources and destinations of phthalic acid esters (PAEs) within these WWTPs using mass balance equations. Wastewater treatment diminished the frequency and concentration of PAEs, and decreased the fraction of short-chain PAEs. We confirmed the increased concentration of PAEs post-primary treatment and modified the mass balance equation. Calculations suggest that weaker "the mix" in winter than in summer and stronger sedimentation in winter than in summer resulted in high efficiency of PAEs removal by winter wastewater treatment. The mass flux of biodegradation was influenced by the combination of biodegradation efficiency and the strength of the particular type of PAEs collected, with no seasonal differences. Mass fluxes for sludge sedimentation were mainly influenced by season and were higher in winter than in summer. This study enhances our understanding of emerging pollutants in manual treatment facilities and offers insights for optimizing wastewater treatment methods for water professionals.

Risk assessment of China's Eastern Route of the South-to-north Water Diversion Project from the perspective of Phthalate Esters occurrence in the impounded lakes

Phthalate esters (PAEs) are widely utilized and can accumulate in lacustrine ecosystems, posing significant ecological and human health hazards. Most studies on PAEs focus on individual lakes, lacking a comprehensive and systematic perspective. In response, we have focused our investigation on characteristic lakes situated along the Eastern Route of the South-to-north Water Diversion Project (SNWDP-ER) in China. We have detected 16 PAE compounds in the impounded lakes of the SNWDP-ER by collecting surface water samples using solid-phase extraction followed by gas chromatography analysis. The concentration of PAEs were found to between 0.80 to 12.92 μg L-1. Among them, Bis (2-ethylhexyl) phthalate (DEHP) was the most prevalent, with mean concentration of 1.56 ± 0.62 μg L-1 (48.44%), followed by Diisobutyl phthalate (DIBP), 0.64 ± 1.40 μg L-1 (19.87%). Spatial distribution showed an increasing trend in the direction of water flow. Retention of DEHP and DIBP has led to increased environmental risks. DEHP, Dimethyl phthalate (DMP) etc. determined by agriculture and human activities. Additionally, Dibutyl phthalate (DBP) and DIBP mainly related to the use of agricultural products. To mitigate the PAEs risk, focusing on integrated management of the lakes, along with the implementation of stringent regulations to control the use of plasticizes in products.

Distribution, seasonal variation and ecological risk assessment of phthalates in the Yitong River, a typical urban watercourse located in Northeast China

Phthalates (PAEs) are a typical class of endocrine disruptors (EEDs). As one of the most commonly used plasticizers, they have received widespread attention due to their wide application in various countries and high detection rates in various environmental media. To be able to clarify the contamination status of PAEs pollutants in a typical northern cold-temperate urban river, 30 water samples from Yitong River in Changchun City, northern China were collected, during the 2023 dry season (March), normal season (May) and wet season (July). Using these samples, a total of 16 target PAEs are investigated. The resulting total PAEs concentrations are: dry season 408 to 1494 ng/L, wet season 491 to 1299 ng/L, and normal season 341 to 780 ng/L. The average concentration of the 16 PAEs over the three seasons is 773 ng/L. Di-2-ethylhexyl phthalate (DEHP) and Dibutyl phthalate (DBP) have the highest concentrations, ranging from 12 to 403 ng/L and 28-680 ng/L respectively. The ecological risks within the Yitong River Basin are evaluated based on the degree of PAEs contamination. DBP and DEHP pose higher risk assessment levels for algae, crustaceans and fish than the other target PAEs. The accurate determination of PAEs provided baseline data on PAEs for the management of the Yitong River, which is of great significance for the prediction of ecological risk assessment and the development of corresponding control measures, supported further research on PAEs in the cold-temperate zone aquatic environments, and shed light on the seasonal variations of PAEs in the Northeast region in the future. Moreover, considering the bioaccumulation and persistence of PAEs, it is necessary to continue to pay attention to the pollution status of cold-temperate zones rivers and the changes in ecological risks in the future.

First Evidence of the Bioaccumulation and Trophic Transfer of Tire Additives and Their Transformation Products in an Estuarine Food Web

The discovery of the significant lethal impacts of the tire additive transformation product N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-Q) on coho salmon has garnered global attention. However, the bioaccumulation and trophic transfer of tire additives and their transformation products (TATPs) within food webs remain obscure. This study first characterized the levels and compositions of 15 TATPs in the Pearl River Estuary, estimated their bioaccumulation and trophic transfer potential in 21 estuarine species, and identified priority contaminants. Our observations indicated that TATPs were prevalent in the estuarine environment. Eight, six, seven, and 10 TATPs were first quantified in the shrimp, sea cucumber, snail, and fish samples, with total mean levels of 45, 56, 64, and 67 ng/g (wet weight), respectively. N,N'-Diphenyl-p-phenylenediamine (DPPD) and N,N'-bis(2-methylphenyl)-1,4-benzenediamine (DTPD) exhibited high bioaccumulation. Significant biodilution was only identified for benzothiazole, while DPPD and DTPD displayed biomagnification trends based on Monte Carlo simulations. The mechanisms of bioaccumulation and trophodynamics of TATPs could be explained by their chemical hydrophobicity, molecular mass, and metabolic rates. Based on a multicriteria scoring technique, DPPD, DTPD, and 6PPD-Q were characterized as priority contaminants. This work emphasizes the importance of biomonitoring, particularly for specific hydrophobic tire additives.