Environmental implications from the priority pollutants screening in impoundment reservoir along the eastern route of China's South-to-North Water Diversion Project

Occurrence, removal, and prioritization of organic micropollutants in four full-scale wastewater treatment plants in Korea

This study investigated the occurrence, removal rate, and potential risks of 43 organic micropollutants (OMPs) in four municipal wastewater treatment plants (WWTPs) in Korea. Results from two-year intensive monitoring confirmed the presence of various OMPs in the influents, including pharmaceuticals such as acetaminophen (pain relief), caffeine (stimulants), cimetidine (H2-blockers), ibuprofen (non-steroidal anti-inflammatory drugs- NSAIDs), metformin (antidiabetics), and naproxen (NSAIDs) with median concentrations of >1 μg/L. Some pharmaceuticals (carbamazepine-anticonvulsants, diclofenac-NSAIDs, propranolol-β-blockers), corrosion inhibitors (1H-benzotriazole-BTR, 4-methyl-1H-benzotriazole-4-TTR), and perfluorinated compounds (PFCs) were negligibly removed during WWTP treatment. The OMP concentrations in the influents and effluents were mostly lower in August than those of other months (p-value <0.05) possibly due to wastewater dilution by high precipitation or enhanced biodegradation under high-temperature conditions. The anaerobic-anoxic-oxic process (A2O) with a membrane bioreactor exhibited higher OMP removal than other processes, such as A2O with sedimentation or the conventional activated sludge process (p-value <0.05). Pesticides (DEET and atrazine), corrosion inhibitors (4-TTR and BTR), and metformin were selected as priority OMPs in toxicity-driven prioritization, whereas PFCs were determined as priority OMPs given their persistence and bioaccumulation properties. Overall, our results contribute to an important database on the occurrence, removal, and potential risks of OMPs in Korean WWTPs.

Prioritization of organic contaminants in China's groundwater based on national-scale monitoring data and their persistence, bioaccumulation, and toxicity

There has been increasing concern regarding the adverse environmental and health effects of organic pollutants. A list of priority control organic pollutants (PCOPs) can provide regulatory frameworks for the use and monitoring of organic compounds in the environment. In this study, 20,010 groundwater samples were collected from 15 "first level" groundwater resource zones in China. Fifty (50) organic compounds were analyzed based on their prevalence, occurrence, and physicochemical properties (persistence, bioaccumulation, and toxicity). Results showed that 16 PCOPs, including 12 pesticides, 3 aromatic hydrocarbons (AHs), and 1 phthalate ester, were recognized. Pesticides and AHs accounted for 75 % and 18.75 % of the high-priority pollutants, respectively. There were significant differences in PCOPs between confined and phreatic groundwater. Higher concentrations of pesticides were mainly detected in phreatic groundwater. PCOPs detected in samples from the 15 groundwater resource zones were mainly pesticides and AHs. The groundwater data indicate that the organic compounds detected in the Yellow River Basin (YRB), Yangtze River Basin (YZB), Liaohe River Basin (LRB), and Songhua River Basin (SRB) are mainly categorized as Q1 (high priority) and Q2 (medium priority) pollutants based on the contaminants ranking system in China. The findings from this study offer a snapshot of the wide distribution of PCOPs in the surveyed regions, and are expected to establishing treatment and prevention measures at both the regional and national levels in China.

The dynamic changes in phytoplankton and environmental factors within Dongping Lake (China) before and after the South-to-North Water Diversion Project

Dongping Lake is one of the most important regulation and storage lakes along the eastern route of the South-to-North Water Diversion Project in China, the water quality condition of which directly influences the safety of water diverting, because it serves as a Yangtze River water redistribution control point. However, the changes in algae, and in environmental factors affecting their community structures, before and after the water diversion project are rarely reported. In this study, the temporal variations of phytoplankton abundance were examined based on monthly samples collected at three stations from May 2010 to April 2022. The total abundance of algae greatly decreased after the water diversion project was implemented, with a relatively stable biodiversity and evenness before and after the water translocation. Multiple statistical methods were used together with the water quality indices (WQIs) and the nutrient status index (TSIM) to evaluate overall water condition and analyse relationships among environmental factors. The WQIs demonstrated a general "Good" water quality with a seasonal differentiation, and that water conditions during water transfer periods were better than during non-water transfer periods, which may be ascribed to the improved hydraulic conditions and purified water environment during water transfer periods. Redundancy analysis showed that water temperature, ammonia nitrogen, water transparency, and total phosphorus were the most important environmental factors, with relatively decreased contribution rates towards phytoplankton communities after the water translocation. Importantly, some dominant phytoplankton genera of Chlorophyta, Bacillariophyceae, and Cyanophyceae were similarly affected by water transparency, and nitrogen and phosphorus nutrients in summer after the water translocation. These research findings helped us gain a comprehensive understanding of the changing patterns of water quality and microalgae and their relationships before and after the water diversion project, providing a guidance for future lake management in regulating hydraulic conditions and improving water quality of Dongping Lake.

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

Lake-river complex systems represent interconnected ecosystems wherein inflow rivers significantly influence the migration of terrigenous contaminants, particularly organic micropollutants (OMPs), into lakes. Given the extensive array of OMPs, screening for those with the highest potential hazard is crucial for safeguarding freshwater lake-river ecosystems. In this study, an optimized multi-criteria scoring method was applied to prioritize OMPs. Flux estimation was then performed to identify the contamination load contributed by the Le'an River to Poyang Lake. Higher concentrations of phthalate esters (PAEs) were detected in the lake-river system, ranging from 1154.5 to 22,732.8 ng/L, followed by antibiotics and polycyclic aromatic hydrocarbons (PAHs), while historical pollutant residues were comparably lower. Based on the prioritization methodology, 27 compounds, encompassing eight PAEs, six organochlorine pesticides (OCPs), six polychlorinated biphenyls (PCBs), five PAHs and two antibiotics, emerged as priority pollutants. Multiple risk assessments revealed that priority PAEs posed relatively high ecological and human health risks; concurrently, the annual fluxes of individual priority PAEs into the lake all exceeded 1000 kg, with DBP, DEHP and BBP fluxes reaching 18,352, 10,429, and 7825 kg, respectively. This research offers valuable insights stemming from OMP prioritization to aid in the conservation of freshwater lake ecosystems, particularly concerning lake-river system integrity.

Microbial community composition and degradation potential of petroleum-contaminated sites under heavy metal stress

Total petroleum hydrocarbons (n-alkanes), semi-volatile organic compounds, and heavy metals pose major ecological risks at petrochemical-contaminated sites. The efficiency of natural remediation in situ is often unsatisfactory, particularly under heavy metal pollution stress. This study aimed to verify the hypothesis that after long-term contamination and restoration, microbial communities in situ exhibit significantly different biodegradation efficiencies under different concentrations of heavy metals. Moreover, they determine the appropriate microbial community to restore the contaminated soil. Therefore, we investigated the heavy metals in petroleum-contaminated soils and observed that heavy metals effects on distinct ecological clusters varied significantly. Finally, alterations in the native microbial community degradation ability were demonstrated through the occurrence of petroleum pollutant degradation function genes in different communities at the tested sites. Furthermore, structural equation modeling (SEM) was used to explain the influence of all factors on the degradation function of petroleum pollution. These results suggest that heavy metal contamination from petroleum-contaminated sites reduces the efficiency of natural remediation. In addition, it infers that MOD1 microorganisms have greater degradation potential under heavy metal stress. Utilizing appropriate microorganisms in situ may effectively help resist the stress of heavy metals and continuously degrade petroleum pollutants.

Seasonal occurrence of multiple classes of antibiotics in East China rivers and their association with suspended particulate matter

Understanding the occurrence and fate of antibiotics from different categories is vital to predict their environmental exposure and risks. This study presents the spatiotemporal occurrence of 45 multi-class antibiotics and their associations with suspended particulate matter (SPM) in Xiaoqing River (XRB) and Yellow River (YRB) via 10-month monitoring in East China. Thirty-five and 31 antibiotics were detected in XRB and YRB, respectively. Among them, fluoroquinolones (FQs) had the highest total mean concentration (up to 24.8 μg/L in XRB and 15.4 μg/L in YRB), followed by sulfonamides (SAs) (14.0 μg/L and 15.4 μg/L) and macrolides (MLs) (1.1 μg/L and 1.6 μg/L). Significant spatial-temporal variations were found in both rivers where higher concentrations of antibiotics were observed in urban and densely populated areas during winter and spring. Hydrological factors such as river flow and water volume, instream attenuation and antibiotic usage may cause the observed variabilities in the seasonal patterns of antibiotic pollution. Using linear regression analysis, for the first time, this study confirmed that the total concentrations of MLs (p < 0.05), FQs (p < 0.001) and SAs (p < 0.001) were strongly correlated with the turbidity/total suspended solids in the studied rivers (except MLs in YRB). It is thus suggested that partitioning processes onto SPM might affect the distribution of detected antibiotics in rivers, which are largely dependent on SPM composition and characteristics. The risk quotient (RQ) determined for up to 87 % of individual compound was below 0.1 in both rivers; however, the high joint toxicity reflected by the mixed RQs of detected antibiotics may rise risk alarm for aquatic species. Further aspects regarding active mechanisms of SPM-antibiotic interactions and ecological risks of coexistence of multiple antibiotics need to be investigated.

Environmental Risk Analysis Based on Characterization of Ground Oily Sludge

Oily sludge is recognized as hazardous waste. To reduce the potential danger and harmful factors of oily sludge, it is very important to analyze its environmental risk. In this paper, the characterization of oily sludge from Shengli Oilfield in China was tested experimentally, including the composition content, particle size, microscopic morphology, heavy metal content, organic composition, inorganic composition, and thermogravimetric analysis, which were used to analyze environmental risks. The results show that the oil content of oily sludge is as high as 10.3%, which will cause serious pollution. It is calculated that China can recover 772.5 million liters of oil and reduce 553.9 million kg of carbon emissions compared with incineration in one year, if the oily sludge can be managed effectively. The content of heavy metals such as Ba, Zn, Cr, As, Ni, Se, Be, and Hg in oily sludge exceeds the standard. It will restrain the self-healing ability of soil, pollute groundwater, and endanger animals and plants. The organic matter of oily sludge is concentrated in C₁₁ to C₂₉. It contains a large amount of benzene series and polycyclic benzene hydrocarbons, which can lead to cancer in the human body. Inorganic substances in oily sludge are mixed with some additives, which can not only reduce the toxicity of heavy metals, but also be used as building materials. The median particle size D₅₀ of oily sludge is 0.91 μm, and it spreads all over the narrow pores. Generally, it needs to be treated under high temperature conditions, which will cause secondary pollution to the environment. The research content of this paper provides a theoretical reference for the management of oily sludge.

Regional-scale investigation of the molecular weight distribution and metal-binding behavior of dissolved organic matter from a shallow macrophytic lake using multispectral techniques

In this work, based on excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-FARAFAC) and two-dimensional correlation analysis of synchronous fluorescence spectroscopy, Fourier transform infrared spectroscopy, and combination of two spectra (2D-SF-COS, 2D-FTIR-COS, and Hetero-2D-COS), the characteristics and metal-binding behaviors of DOM in Dongping Lake were explored for molecular weight (MW), fluorescence components, and functional groups. The results showed that the entire lake was governed by protein-like materials with low MW(< 1 kDa). The complexation occurred preferentially in protein-like materials for bulk DOM after adding copper (Cu²⁺) and lead (Pb²⁺), which were changed by fractionation for MW. The active points were aliphatic C－OH for DOM-Cu and phenol －OH or polysaccharide for DOM-Pb from 2D-FTIR-COS. The protein-like components possessed higher LogK than humic-like component during binding to Cu²⁺ or Pb²⁺. Moreover, the complexing affinities of DOM-Cu (LogK_Cu: 3.26 ± 0.87-4.04 ± 0.49) were higher than those of DOM-Pb (LogK_Pb: 2.66 ± 0.52-3.78 ± 0.36). On a spatial scale, high LogK_Cu and LogK_Pb were found in the center and entrance of the lake, respectively. Humic-like component C2 in the LMW fraction possessed a stronger binding capacity with Cu²⁺. This study affords new insights into the migration and conversion of HMs in lakes.

A comprehensive evaluation of organic micropollutants (OMPs) pollution and prioritization in equatorial lakes from mainland Tanzania, East Africa

A lack of understanding the fate of highly toxic organic micropollutants (OMPs) in the equatorial lakes of Tanzania hinders public awareness for protecting these unique aquatic ecosystems, which are precious water resources and stunning wildlife habitats. To address this knowledge gap, the occurrence of 70 anthropogenically-sourced OMPs, including phthalates (PAEs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), was investigated in the water and sediment of 18 lakes in Tanzania. Similar residue concentrations were found in both compartments, showing higher pollution of PAEs ranging from 835.0 to 13,153.1 ng/L in water and 244.6-8691.8 ng/g dw in sediment, followed by PAHs, while OCPs and PCBs were comparatively lower. According to the multi-criteria scoring method for prioritization, the final OMP priority list for the lake environment in Tanzania comprised 25 chemicals, specifically 5 PAEs (DEHP, DIBP, DBP, DCHP and DMPP), 6 PCBs (PCB153, PCB105, PCB28, PCB156, PCB157 and PCB167), 6 PAHs (BaP, BaA, BbF, Pyr, DahA and InP) and 8 OCPs (cis-chlordane, trans-chlordane, p,p'-DDD, p,p'-DDE, p,p'-DDT, endrin, methoxychlor and heptachlor epoxide), suggesting the key substances for conventional monitoring and pollution control in these equatorial lakes, with an emphasis on PAEs, especially DEHP, due to the top priority and endocrine disruptor properties.

Multi-spectroscopic investigation of the molecular weight distribution and copper binding ability of dissolved organic matter in Dongping Lake, China

The properties and metal-binding abilities of dissolved organic matter (DOM) rely on its molecular weight (MW) structure. In this study, the spatial differences of DOM in compositions, MW structures, and binding mechanisms with copper (Cu²⁺) in Dongping Lake were investigated by applying excitation-emission matrix combining parallel factor analysis (EEM-PARAFAC), synchronous fluorescence (SF) spectra, two-dimensional correlation spectra (2D-COS), and Fourier transform infrared (FTIR) spectra. The EDOM for the entrance of the Dawen River and PDOM for the macrophyte-dominated region were divided from DOM of Dongping Lake based on hierarchical clustering analysis (HCA) and principal component analysis (PCA) and were size-fractioned into MW < 500 kDa and <100 kDa fractions. According to EEM-PARAFAC, Dongping Lake was dominated by tryptophan-like substances with MW < 500 kDa. The concentration of PDOM was higher than that of EDOM (p < 0.05). 2D-COS showed that protein-like components preceded humic-like components binding to Cu²⁺ regardless of sample type (215 nm > 285 nm > 310-360 nm). The Cu²⁺ binding capacity of DOM exhibited specific differences in space, components, and molecular weights. The humic-like component 1 (C1) and tryptophan-like component 4 (C4) of PDOM showed stronger binding abilities than those of EDOM. Endogenous tryptophan-like component 4 (C4) had a higher binding affinity for Cu²⁺ than humic-like components (logK_a: C4 > C1 > C2) in PDOM irrespective of MW. Humic-like components with MW < 500 kDa displayed higher binding potentials for Cu²⁺. FTIR spectra showed that the main participants of DOM-Cu complexation included aromatic hydrocarbons, aliphatic groups, amide Ⅰ bands, and carboxyl functional groups. This study provides spatial-scale insights into the molecular weight structure of DOM in influencing the behavior, fate, and bioavailability of heavy metals in lakes.