Organonitrogen pesticides in Beibu gulf seawater: spatiotemporal distribution, key influencing factors, sources, and ecological risks.

Occurrence, Source Apportionment, and Risk Assessment of Organophosphate Esters in Zhuozhang River, North China

As the primary substitutes for traditional brominated flame retardants, organophosphate esters (OPEs) are widely employed in industrial manufacturing and consumer products, and they have been detected in most rivers across China. The Zhuozhang River, a major tributary of the Haihe River, is situated in a region characterized by intensive anthropogenic activities and water scarcity. Nevertheless, research on OPE contamination and its associated environmental impacts in the Zhuozhang River basin remains limited. To address this knowledge gap, this study investigated the occurrence, sources, and ecological risks of 12 OPEs in water samples collected from representative sites, including major reservoirs, upstream river sections, main river channels, and wastewater treatment plants. The results showed that tris(2-chloroethyl) phosphate (TCEP) and triethyl phosphate (TEP) were the dominant compounds by mass, with concentrations ranging from 1108 to 1977 ng/L and 202 to 238 ng/L in the mainstream. Ecological risk assessment using the RQ method revealed that EHDPP and TDCIPP fall into the moderate-risk category. The positive matrix factorization (PMF) model was applied to explore the sources of OPEs. The results show that plastic-related industries most likely serve as the dominant contributors to OPE contamination.

Regional accumulation and ecological risks of typical plastic additives in agricultural soils in China.

Phthalates (PAEs) and organophosphate esters (OPEs) have been widely detectable in agricultural soils and pose potential risks to ecosystems. However, their regional variations and the influencing factors in agricultural soils in China remain unclear. To address these issues, we assessed the regional accumulation and combined ecological risks of PAEs and OPEs in agricultural soils across China using the literature data, and then analysed their influencing factors from the perspectives of pollutant property parameters, soil physicochemical properties, meteorological conditions, agricultural activities, and geographical variables using Random Forest models and multi-source spatial data. The results showed that the mean concentration of Σ6PAEs (1591 ± 1610 ng/g) was generally higher than that of Σ11OPEs (52.6 ± 111 ng/g). Di-(2-ethylhexyl) phthalate (DEHP) (791 ± 902 ng/g) and Σ5Alkyl-OPEs (29.2 ± 88.9 ng/g) were the dominant compounds. The combined ecological risks of the Σ6PAEs and Σ11OPEs were the highest in agricultural soils in Eastern China (median risk quotient (RQ): 3.75). PAEs showed high risks (RQ ≥ 1) across China, whereas OPEs exhibited moderate risks (0.1 ≤ RQ < 1) except in the West (RQ < 0.1). The importance of pollutant property parameters for PAE and OPE accumulation in agricultural soils reached 49.9 ± 6.44% and 28.9 ± 2.24%, respectively. The soil physicochemical properties and meteorological parameters contributed higher impacts on the OPEs than on the PAEs, especially the precipitation, which contributed 9.13 ± 0.56% to OPEs. These findings provide scientific support for the ecological risk evaluation and environmental management of plastic additives in agricultural soils.

Occurrence and risk assessment of contaminants of emerging concern in water from the Danube River and its tributaries in Serbia

This study investigated the occurrence of 116 contaminants of emerging concern (CECs) in surface waters of the Danube River section within Serbia, along with its major tributaries (the Tisa, Sava, and Tamiš rivers) and the Great Bačka Canal. Analysis was performed using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) system Q-Exactive Orbitrap. Surface grab water samples were collected at 24 locations during multiple sampling campaigns (November 2022, April 2023, and November 2023) to assess the prevalence, frequency, and spatial–temporal distribution of target CECs. The studied compounds, some of their metabolites and/or transformation products encompassed five classes: pharmaceuticals (100 analytes), sweeteners (6), pesticides (4), personal care products (3), and industrial chemicals (3). Of the 116 targeted CECs, 44 were detected, including 37 pharmaceuticals, 4 sweeteners, 2 industrial chemicals, and 1 UV filter. Caffeine, sulfamethoxazole, tramadol, and climbazole were found in 100% of samples. The frequent detection of caffeine, selected pharmaceuticals, and sweeteners (acesulfame, sucralose, and cyclamate, present in >90% of samples) indicated their widespread presence in the studied watercourses. Campaign-to-campaign variability was evident for certain anti-inflammatory compounds (salicylic acid, diclofenac, ketoprofen), antidepressants (venlafaxine, citalopram), and the UV filter sulisobenzone (BP4), which appeared in both November campaigns (November 2022 and November 2023) but was not detected in April 2023. The environmental risk assessment, expressed as risk quotients (RQs), suggested that most detected compounds posed negligible ecological risks (< 0.01). This study provides a harmonized, network-scale overview of the occurrence of CECs across the investigated Serbian Danube River network, thereby complementing and expanding the existing data for Serbian surface waters and contributing to the broader evidence base on CECs in Western Balkan watercourses. While most individual risk quotient values indicated negligible screening-level ecological risk, the frequent detection of selected pharmaceuticals and artificial sweeteners points to continuous wastewater-related inputs and/or persistence in the studied watercourses. These findings may support the prioritization of selected CECs in future national and regional monitoring programmes and provide a useful evidence base for water-quality management and policy-oriented discussions.

Spatiotemporal Distribution and Ecological Risks of Trace Metals in a Marine Protected Area of the Northwestern Arabian Gulf

Dissolved bio-essential trace metals (Cu, Zn, Co, Ni, and Fe) in seawater and 17 elements in surface sediments were studied to assess the metal contamination and associated ecological risks in the Sulaibikhat Bay Marine Protected Area (MPA) in the northwestern Arabian Gulf. Dissolved metals were mostly at low to moderate levels and within the limits of most international water quality standards. However, dissolved Cu concentrations (0.54 to 4.73 µg L−1) in the MPA stations (MPA-1 and MPA-2) exceeded the Oslo–Paris Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) ecotoxicological assessment thresholds, suggesting possible adverse ecological effects. Sediment showed higher levels of Cd, Cr, Ni, V, Cu, and Zn at stations within the MPA, with Principal Component Analysis (PCA) linking these enrichments to nearby industrial and desalination discharge sources. The calculated enrichment factor (EF) and geoaccumulation index (Igeo) values confirmed moderate to substantial anthropogenic contributions for Cd, Cr, and Ni, while the major lithogenic elements were derived from natural mineralogical inputs. A pollution load index (PLI) > 1 at stations MPA-1, MPA-3 and MPA-4 in Sulaibikhat Bay indicated cumulative metal contamination. Ecological risk assessment criteria classified sediments within the MPA and Sulaibikhat Bay as having a moderate level of ecological risk, with Cd identified as the principal contributor. The toxicological indices, namely mean Effect Range Median Quotient (m-ERM-Q) and mean Probable Effect Level Quotient (m-PEL-Q), indicated a low-to-moderate probability of adverse biological effects due to Cu and Ni exposure in the MPA. In contrast, the reference station in the Kuwait Bay showed very low contamination and negligible ecological risk. These findings stress the need for continuous monitoring and effective source control to protect the ecosystem of this newly established MPA in Kuwait.

Assessment of Metal Contamination and Human Health Risk in the Buffalo River Estuary, Eastern Cape, South Africa.

Metal contamination in estuarine environments poses environmental and public health concerns, particularly where surface waters support domestic and subsistence uses. This study assessed the seasonal distribution, controlling mechanisms, and non-carcinogenic health risks of selected metals (Mg, Al, Ba, Fe, Mn, and Zn) in the Buffalo River Estuary, Eastern Cape, South Africa. Water samples were collected from 11 stations during wet and dry seasons and analyzed using standard methods. Descriptive statistics, Pearson's correlation analysis, and principal component analysis (PCA) were applied to evaluate metal distribution, inter-element relationships, and dominant controlling processes. Marked seasonal variability was observed, with higher concentrations of Al (97-1708 μg/L), Ba (7.4-29 μg/L), Fe (54-1751 μg/L), Mn (4-116 μg/L), and Zn (4-23 μg/L) during the wet season, while Mg concentrations were elevated in the dry season (10686-851 382 μg/L) relative to the wet season (1056-1313 μg/L). PCA indicated that wet-season metal dynamics were governed by lithogenic and hydrological processes linked to runoff and suspended sediments, whereas dry-season variability reflected sedimentary geochemical controls, redox processes, conservative mixing, and secondary anthropogenic inputs. Non-carcinogenic health risk assessment for Al, Ba, Fe, Mn, and Zn showed Mn as the largest contributor to risk, although cumulative hazard indices for adults (2.19 × 10-2-1.39 × 10-1) and children (8.10 × 10-2-5.01 × 10-1) remained below unity, indicating low health risk. These findings highlight the dominance of seasonal geochemical processes, providing essential baseline data for water-quality management, and underscore the need for continued monitoring to support effective water-resource management.

Occurrence, distribution, and ecological risk of microplastics in Chinese surface waters: a systematic review and multi-model assessment