Present study aims to unravel the hydro geochemical interaction of sediment and water of Saheb bandh lake, West Bengal, India with an emphasis on heavy metal assessment. Lake water belongs to Ca2+–HCO3− type hydro geochemical faces and water-rock interaction primarily controls the lake water chemistry. Based on different Hydro chemical characteristics it is suggested that silicate weathering is the major hydro geochemical process operating in Saheb bandh lake water. Regarding point source contribution of pollutants the average value of NO3-N, TP and Hg are much higher in inlet water (7.5 mg/L, 1.29 mg/L and 8.5 μg/L) than the lake water (1.5 mg/L, 0.05 mg/L and 0.42 μg/L). Risk assessment indices suggest advanced decline of the sediment quality. Water-sediment interaction of heavy metals reveals that Cd, As, Pb and Hg metals enter into lake water as a result of not only natural processes but also of direct and indirect activities of humans. This study recommends that continuous monitoring of these metals in water and sediment and other aquatic biota of Saheb bandh should be directed to assess the risk of these vital heavy metals in order to maintain the safe ecology in the vicinity of this lake.

International audience | Biocides are added to or applied on building materials to prevent microorganisms from growing on their surface or to treat them. They are leached into building runoff and contribute to diffuse contamination of receiving waters. This review aimed at summarizing the current state of knowledge concerning the impact of biocides from buildings on the aquatic environment. The objectives were (i) to assess the key parameters influencing the leaching of biocides and to quantify their emission from buildings; (ii) to determine the different pathways from urban sources into receiving waters; and (iii) to assess the associated environmental risk. Based on consumption data and leaching studies, a list of substances to monitor in receiving water was established. Literature review of their concentrations in the urban water cycle showed evidences of contamination and risk for aquatic life, which should put them into consideration for inclusion to European or international monitoring programs. However, some biocide concentration data in urban and receiving waters is still missing to fully assess their environmental risk, especially for isothiazolinones, iodopropynyl carbamate, zinc pyrithione and quaternary ammonium compounds, and little is known about their transformation products. Although some models supported by actual data were developed to extrapolate emissions on larger scales (watershed or city scales), they are not sufficient to prioritize the pathways of biocides from urban sources into receiving waters during both dry and wet weathers. Our review highlights the need to reduce emissions and limit their transfer into rivers, and reports several solutions to address these issues.

Ninety-eight soil samples were collected from farmland soils from Beijing-Tianjin-Hebei core area, Northern China, where agricultural lands were subjected to contamination from intense urban and industrial activities. Twelve organophosphates flame retardants (OPFRs) were analyzed with total soil concentrations ranging from 0.543 μg/kg to 54.9 μg/kg. Chlorinated OPFRs were dominating at mean level of 3.64 μg/kg and Tris(2-chloroisopropyl) phosphate contributed the most (mean 3.36 ± 5.61 μg/kg, 98.0%). Tris(2-ethylhexyl) phosphate was fully detected at levels of 0.041–1.95 μg/kg. Generally, tris(2-butoxyethyl) phosphate and triphenyl phosphate contributed the most to alkyl- (53.6%) and aryl-OPFRs (54.3%), respectively. The levels of ∑OPFRs close to the core urban areas were significantly higher than those from background sites. The occurrence and fate of OPFRs in soil were significantly associated with total organic carbon content and mostly with fine soil particles (<0.005 mm), and a transfer potential from the atmosphere was predicted with logKSA values. Comparable soil levels with poly brominated diphenyl ethers s in other studies suggested that the contamination of OPFRs occurred in farmland soil with an increasing trend but currently showed no significant environmental risk based on risk quotient estimation (<1). This investigation warrants further study on behaviors of OPFRs in a soil system and a continual monitoring for their risk assessment.

This study aimed to evaluate and qualify field-based potential risks of seven neonicotinoid and phenylpyrazole (fipronil) insecticides on aquatic invertebrates, including estuary-resident marine crustaceans. One hundred and ninety-three estuarine water samples, with salinity ranging from 0.5 to 32.7, were collected from four estuarine sites in the Seto Inland Sea of Japan, in 2015–2018 and the insecticide levels were measured. Five neonicotinoid and fipronil insecticides were successfully identified, and their occurrence varied temporally. Marine crustaceans were simultaneously harvested every month from one of the estuarine water sampling sites in 2015–2017. Three predominant crustacean species, kuruma prawn (Penaeus japonicus), sand shrimp (Crangon uritai), and mysid (Neomysis awatschensis), were captured and their seasonal presence was species independent. A 96-h laboratory toxicity study with the insecticides using kuruma prawn, sand shrimp, and a surrogate mysid species (Americamysis bahia) indicated that fipronil exerted the highest toxicity to the three crustaceans. Using both toxicity data and insecticide occurrence in estuarine water (salinity ≥10, n = 169), the potential risks on the three marine crustaceans were quantified by calculating the proportion of mixture toxicity effects (Pₘᵢₓ). The Pₘᵢₓ of seven neonicotinoids on the crustaceans was less than 0.8%, which is likely to be too low to indicate adverse effects caused by the insecticides. However, short temporal detection of fipronil (exclusively in June and July) significantly affected the Pₘᵢₓ, which presented the maximal Pₘᵢₓ values of 21%, 3.4%, and 72% for kuruma prawn, sand shrimp, and mysid, respectively, indicating a significant effect on the organisms. As for estuarine water (salinity <10), some water samples contained imidacloprid and fipronil exceeding the freshwater benchmarks for aquatic invertebrates. The present study provides novel insights into the seasonally varying risks of insecticides to estuarine crustaceans and highlights the importance of considering whether ecological risk periods coincide with crustacean presence.

Polycyclic aromatic hydrocarbons containing at least 24 carbon atoms (≥C₂₄-PAH) are often associated with pyrogenic processes such as combustion of fuel, wood or coal, and occur in the environment in diesel particulate matter, black carbon and coal tar. Some of the ≥C₂₄-PAH, particularly the group of dibenzopyrenes (five isomers, six aromatic rings) are known to show high mutagenic and carcinogenic activita.Gas chromatography – mass spectrometry is a well-established method for the analysis of lower molecular weight PAH but is not optimally suited for the analysis of ≥C₂₄-PAH due to their low vapor pressures. Also, hundreds of ≥C₂₄-PAH isomers are possible but only a few compounds are commercially available as reference standards. Therefore, in this study, a combination of multidimensional liquid chromatography, UV–Vis diode array detection, PAH selective and highly sensitive atmospheric pressure laser ionization – mass spectrometry is used to detect and unequivocally identify PAH. For identification of PAH in two bituminous coals and one petrol coke sample, unique and compound specific UV–Vis spectra were acquired. It was possible to identify ten compounds (naphtho[1,2,3,4-ghi]perylene, dibenzo[b,ghi]perylene, dibenzo[e,ghi]perylene, dibenzo[cd,lm]perylene, benzo[a]coronene, phenanthrol[5,4,3,2-abcde]perylene, benzo[ghi]naphtho[8,1,2-bcd]perylene, benzo[pqr]naphtho[8,1,2-bcd]perylene, naphtho[8,1,2-abc]coronene and tribenzo[e,ghi,k]perylene) by comparison of acquired spectra with spectra from literature. Additionally, it was possible to detect similar distribution patterns in different samples and signals related to alkylated naphthopyrenes, naphthofluoranthenes or dibenzopyrenes. Subsequent effect-directed analysis of a bituminous coal sample using the microEROD (ethoxyresorufin-O-deethylase) bioassay showed high suitability and revealed lower EROD induction for the ≥C₂₄-PAH (TEQ range 0.67–10.07 ng/g) than for the allover < C₂₄-PAH containing fraction (TEQ 84.00 ng/g). Nevertheless, the toxicity of ≥C₂₄-PAH has a significant impact compared with <C₂₄-PAH and must be considered for risk assessment. The LC-DAD-APLI-MS method, presented in this study, is a powerful tool for the unequivocal identification of these ≥ C₂₄-PAH.

The consumption of tonnes of anti-tubercular and other anti-microbial compounds for the control of the tuberculosis epidemic and other opportunistic diseases associated with human immunodeficiency virus presents tuberculosis-endemic countries such as South Africa, with a problem regarding the occurrence and fate of these compounds in the aquatic environment. The majority of these compounds are not readily degradable and could persist in the aquatic environment with potential detrimental effect on the aquatic microbiota ecosystem, development and dissemination of anti-microbial resistance as well as chronic toxicity in humans due to long-term exposure. This review summarises and discusses the occurrence, fate and potential adverse effects of the commonly administered anti-tubercular compounds in the aquatic environment in tuberculosis-endemic countries and South Africa in particular. It further attempts to identify information gaps in the literature regarding anti-tubercular compounds in the environment that needs further investigation so that their risk can be comprehensively assessed and impact mitigated.

Reduced graphene oxide (rGO) is one of the most widely used carbon nanomaterials. When it is released into the environment, rGO can markedly affect the transformation of many pollutants, and change their fate and risk. In this work, the synergetic effects of rGO and Cu(II) on the oxidation of 2-naphthol were examined in water in the dark. It was found that the coexistence of rGO and Cu(II) significantly promoted the oxidation of 2-naphthol. Corresponding products were identified as the coupling oligomers of 2-naphthol (dimer, trimer and tetramer) and hydroxylated compounds (OH-2-naphthol, OH-dimer, di–OH–dimer and naphthoquinone derivatives). In the oxidation reaction, rGO played dual roles, i.e. adsorbent and electron-transfer mediator. rGO firstly adsorbed Cu(II) and 2-naphthol on its surface, and then transferred electrons from 2-naphthol to Cu(II) to yield 2-naphthol radicals and Cu(I). 2-Naphthol radicals coupled to each other to form different oligomers of 2-naphthol. Cu(I) was re-oxidized back to Cu(II) by dissolved oxygen, which sustained the continuous oxidation of 2-naphthol. During the autoxidation of Cu(I), reactive oxygen species were generated, which further reacted with 2-naphthol to form hydroxylated products. These findings provide new insights into the risk assessment of rGO and 2-naphthol in aquatic environments.

Food dyes, or color additives, are chemicals added to industrial food products and in domestic cooking to improve the perceived flavor and attractiveness. Of natural and synthetic origin, their safety has been long discussed, and concern for human safety is now clearly manifested by warnings added on products labels. Limited attention, however, has been dedicated to the effects of these compounds on aquatic flora and fauna. For this reason, the toxicity of four different commercially available food dyes (cochineal red E120, Ponceau red E124, tartrazine yellow E102 and blue Patent E131) was assessed on three different model organisms, namely Cucumis sativus, Artemia salina and Danio rerio that occupy diverse positions in the trophic pyramid. The evidence collected indicates that food dyes may target several organs and functions, depending on the species. C. sativus rate of germination was increased by E102, while root/shoot ratio was ∼20% reduced by E102, E120 and E124, seed total chlorophylls and carotenoids were 15–20% increased by E120 and 131, and total antioxidant activity was ∼25% reduced by all dyes. Mortality and low mobility of A. salina nauplii were increased by up to 50% in presence of E124, E102 and E131, while the nauplii phototactic response was significantly altered by E102, E120 and E124. Two to four-fold increases in the hatching percentages at 48 h were induced by E124, E102 and E131 on D. rerio, associated with the occurrence of 20% of embryos showing developmental defects. These results demonstrated that the food dyes examined are far from being safe for the aquatic organisms as well as land organisms exposed during watering with contaminated water. The overall information obtained gives a realistic snapshot of the potential pollution risk exerted by food dyes and of the different organism' ability to overcome the stress induced by contamination.

Triclocarban (TCC) is used as a broad-spectrum antimicrobial agent, the intensive detection of TCC in aquatic environments and its potential risks to aquatic organisms are concerned worldwide. In this study, 8 Chinese resident aquatic organisms from 3 phyla and 8 families were used for the toxicity tests, and four methods were employed to derive the aquatic life criteria (ALC). A criterion maximum concentration (CMC) of 1.46 μg/L and a criterion continuous concentration (CCC) of 0.21 μg/L were derived according to the USEPA guidelines. The acute predicted no effect concentrations (PNECs) derived by species sensitivity distribution (SSD) methods based on log-normal, log-logistic and Burr Type Ⅲ models were 2.64, 1.88 and 3.09 μg/L, respectively. The comparisons of ALCs derived with resident and non-resident species showed that the CMC and CCC of TCC derived with Chinese resident species could provide a sufficient protection for non-resident species. The higher toxicity of TCC on aquatic organisms was found compared with other antimicrobial agents (except for Clotrimazole) in aquatic environment. The strong positive linear correlation was observed between the TCC and TCS concentrations in aquatic environment with a correlation coefficient (R²) of 0.8104, it is of great significance in environmental monitoring and risk assessment for TCC and TCS. Finally, the ecological risk assessment showed that the TCC in Yellow River basin and Pearl River basin had higher risk with the mean potential affected fractions (PAFs) of 9.27% and 7.09%, and 22.10% and 15.00% waters may pose potential risk for 5% aquatic organisms, respectively. In general, the risk of TCC in Asian waters was higher than that in Europe and North America.

Predicting the cotransport of functional microorganisms and heavy metals in porous media is essential to both bioremediation and pollutant risk assessment. In this study, batch and column experiments were conducted to explore the cotransport behaviors of functional bacteria (FA1) and heavy metals (Pb²⁺/Cd²⁺) in saturated sand media under different conditions. The sorption capacity of heavy metals on FA1 was much greater than that of the sand, while both FA1 and sand showed stronger affinity to Pb²⁺ than Cd²⁺. The surface properties, especially zeta potential, of the bacteria and sand were altered by metal adsorption. As a result, the co-existence of Pb²⁺ decreased the transport of FA1 more significantly than that of Cd²⁺, and the influence was more significant with higher heavy metal concentration. On the other hand, the co-existence of FA1 inhibited the mobility of Pb²⁺ and Cd²⁺ in most scenarios, except when the cotransport concentration of Pb²⁺ was 5 mg L⁻¹, and the inhibition was more pronounced for Pb²⁺ than Cd²⁺. Increase in metal concentrations decreased the FA1-associated Pb²⁺/Cd²⁺ in effluents due to the remarkable decrease in FA1 mobility, and free soluble Pb²⁺/Cd²⁺ became the major migration species. In addition, due to stronger attractive forces and affinity between Pb²⁺ and FA1, nearly all presorbed-Pb²⁺ by sand was remobilized by FA1 and transported mainly in FA1-associated form other than soluble Pb²⁺. Findings from this study indicated that the cotransport of biocolloids and heavy metals are highly sensitive to the ion type and concentration, and evaluation of their transport in the subsurface should be carefully carried out to avoid inaccurate estimations.