Persistent organic pollutants (POPs) in fish species from different lakes of the lesser Himalayan region (LHR), Pakistan: The influence of proximal sources in distribution of POPs

Universal occurrence of organophosphate tri-esters and di-esters in marine sediments: Evidence from the Okinawa Trough in the East China Sea

Despite numerous data on organophosphate tri-esters (tri-OPEs) in the environment, literatures on organophosphate di-esters (di-OPEs) in field environment, especially marine sediments remain scarce. This study addresses this gap by analyzing 35 abyssal sediment samples from the middle Okinawa Trough in the East China Sea. A total of 25 tri-OPEs and 10 di-OPEs were determined, but 13 tri-OPEs and 2 di-OPEs were nondetectable in any of these sediment samples. The concentrations of ∑12tri-OPE and ∑8di-OPE were 0.108-32.2 ng/g (median 1.11 ng/g) and 0.548-15.0 ng/g (median 2.74 ng/g). Chlorinated (Cl) tri-OPEs were the dominant tri-esters, accounting for 47.5 % of total tri-OPEs on average, whereas chlorinated di-OPEs represented only 19.2 % of total di-OPEs. This discrepancy between the relatively higher percentage of Cl-tri-OPEs and lower abundance of Cl-di-OPEs may be ascribed to the stronger environmental persistence of chlorinated tri-OPEs. Source assessment suggested that di-OPEs were primarily originated from the degradation of tri-OPEs rather than industrial production. Long range waterborne transport facilitated by oceanic currents was an important input pathway for OPEs in sediments from the Okinawa Trough. These findings enhance the understanding of the sources and transport of OPEs in marine sediments, particularly in the Okinawa Trough.

Differential accumulation of metals in the lacustrine and fluvial Alpine bullheads (Cottus poecilopus) and recovery of fish from metal contamination after a flash flood

The spatiotemporal distribution and transport of mercury, zinc, molybdenum, rubidium, and strontium from alpine terrestrial ecosystems to alpine lake and mountain stream populations of Cottus poecilopus were investigated. Metals were measured for 66 wild fish collected from different lakes and Javorinka stream across. Mercury was measured in the pectoral fins, other elements in the skull. Bullheads contained more metals in the alpine lakes than in the mountain stream. In particular, mercury and zinc concentrations in lake bullheads were 6 and 2.5 times higher, respectively, than those of stream-dwelling fish. New data were generated on metal bioaccumulation in fish of understudied West Carpathian alpine lake environments. In July 2018, a major flood occurred in the area of the Javorinka. Already then, the mercury content in bullheads increased significantly. Bioaccumulation of mercury in fish occurred very quickly after the flood and was also significant in the following 2019. Then, the concentrations of mercury quickly decreased up to 70% in 2021-2022. Average concentrations of molybdenum and rubidium in bullheads in the stream rapidly declined in the year following the flood disturbance, but within less than 2 years, the metal levels stabilized at about the same level as in 2017 prior the flood. Strontium concentrations in fish dropped rapidly immediately after the flood, increased in the following years, and dropped again after 4 years, suggesting that many more factors are influencing strontium bioaccumulation in fish that are comparable in magnitude to the flood. The most serious warning seems to be the absence of biogenic zinc. The average concentration in the Alpine bullheads population in the stream has declined by 70% in less than 5 years and is steadily declining. An important result of this study is the demonstration that disturbance by a single factor (heavy rainfall and flooding) has a clear and timely effect on average metal concentrations in the fish population.

Spatial distribution, source identification and flux estimation of polycyclic aromatic hydrocarbons and organochlorine pesticides in basins of the Eastern Indian Ocean

Although polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) have been recorded worldwide, information on their presence in the Eastern Indian Ocean (EIO), especially south of 10°S, remains limited. We investigated the distribution and depositional fluxes of PAHs and OCPs, and the major sources and ecological risks of PAHs in EIO surface sediments from the Central Indian Ocean (CIOB) and Wharton Basin (WB). The concentration of Σ18 PAHs and ∑10 OCPs had an average value (± SD) of 138.4 ± 52.34 and 0.8 ± 0.20 ng g-1, respectively. PAHs may mainly affected by traffic emission and biomass and wood combustion. Persistent organic pollutant accumulation rate (PAR) and depositional flux (DF) values showed that abundant PAHs might lost during top-down transport. The low trans- chordane (CHL)/cis-CHL ratio and PAR of OCPs may indicated few OCPs were inputted into the EIO recently. The results of binary isotope mixing modeling indicate the predominance of marine organic matter (MOM) in total organic carbon (TOC) of sediments. Fluoranthene (Flour) and pyrene (Py) might have potential biological effects in the EIO. The study provided background values for PAHs and OCPs in the Indian Ocean, and preliminarily revealed the fate of POPs in the open oceans.

Advances and challenges in biocathode microbial electrolysis cells for chlorinated organic compounds degradation from electroactive perspectives

Microbial electrolysis cell (MEC) is a promising in-situ strategy for chlorinated organic compound (COC) pollution remediation due to its high efficiency, low energy input, and long-term potential. Reductive dechlorination as the most critical step in COC degradation which takes place primarily in the cathode chamber of MECs is a complex biochemical process driven by the behavior of electrons. However, no information is currently available on the internal mechanism of MEC in dechlorination from the perspective of the whole electron transfer procedure and its dependent electrode materials. This review addresses the underlying mechanism of MEC on the fundamental of the generation (electron donor), transmission (transfer pathway), utilization (functional microbiota) and reception (electron acceptor) of electrons in dechlorination. In addition, the vital role of varied cathode materials involved in the entire electron transfer procedure during COC dechlorination is emphasized. Subsequently, suggestions for future research, including model construction, cathode material modification, and expanding the applicability of MECs to removal gaseous COCs have been proposed. This paper enriches the mechanism of COC degradation by MEC, and thus provides the theoretical support for the scale-up bioreactors for efficient COC removal.

Review of scientific literature on available methods of assessing organochlorine pesticides in the environment

Organochlorine pesticides (OCPs) are persistent organic pollutants (POPs) widely used in agriculture and industry, causing serious health and ecological consequences upon exposure. This review offers a thorough overview of OCPs analysis emphasizing the necessity of ongoing work to enhance the identification and monitoring of these POPs in environmental and human samples. The benefits and drawbacks of the various OCPs analysis techniques including gas chromatography-mass spectrometry (GC-MS), gas chromatography-electron capture detector (GC-ECD), and liquid chromatography-mass spectrometry (LC-MS) are discussed. Challenges associated with validation and optimization criteria, including accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ), must be met for a method to be regarded as accurate and reliable. Suitable quality control measures, such as method blanks and procedural blanks, are emphasized. The LOD and LOQ are critical quality control measure for efficient quantification of these compounds, and researchers have explored various techniques for their calculation. Matrix interference, solubility, volatility, and partition coefficient influence OCPs occurrences and are discussed in this review. Validation experiments, as stated by European Commission in document SANTE/11813/2017, showed that the acceptance criteria for method validation of OCP analytes include ≤20 % for high precision, and 70-120 % for recovery. This may ultimately be vital for determining the human health risk effects of exposure to OCP and for formulating sensible environmental and public health regulations.

Distribution, bioaccumulation, and health risk assessment of organochlorines across the riverine ecosystem of Punjab Province, Pakistan

This study was designed to assess the distribution of organochlorines (OCs) in fish species, their spatio-temporal variations, bioaccumulation potential, and associated human health risks via dietary intake. The levels of twenty-three organochlorine pesticides (OCPs) and thirty-five polychlorinated biphenyls (PCBs) were analyzed in six fish species collected from the riverine ecosystem of Punjab Province, Pakistan. The results indicated that the mean levels of Σ23OCPs were 74.1 ng/g ww and 184 ng/g ww, and for Σ35PCBs the levels were 38.8 ng/g ww and 74.8 ng/g ww in herbivorous and carnivorous fish species, respectively. The most abundant contaminants in all fish species were DDTs (65%) and HCHs (14%) among OCPs and heavier PCB congeners (62%) among PCBs. As for dioxin-like PCBs, the WHO toxic equivalency values (ng TEQ/g ww) were in the range of 0.21 (Cyprinus Carpio) to 2.38 (Rita Rita), exceeding the maximum allowable limit of 0.004 ng TEQ/g, ww by the European Commission. Spatio-temporal analysis indicated relatively higher OC levels in winter season with elevated concentrations in fish samples from industrial zone. The bioconcentration factor (L/kg) values ranged from 723 to 2773 for PCBs and 315 to 923 for OCPs in all fish species, with higher levels were reported in carnivorous species. The human health risk assessment at both 50th and 95th percentiles revealed the absence of any significant non-carcinogenic risk as calculated HR was less than 1. However, the critical carcinogenic risk was found to be associated for most of the contaminants, signifying the dietary exposure to OCPs and PCBs might pose the public health concern.

Legacy persistent organic pollutants (POPs) in eggs of night herons and poultries from the upper Yangtze Basin, Southwest China

Black-crowned night heron (Nycticorax nycticorax) eggs have been identified as useful indicators for biomonitoring the environmental pollution in China. In this study, we investigated thirty eggs of black-crowned night heron collected from the upper Yangtze River (Changjiang) Basin, Southwest China, for the occurrence of legacy persistent organic pollutants (POPs), including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs). Our results showed a general presence of POPs in night heron eggs with OCPs being the dominant contaminants, having a geometric mean concentration of 22.2 ng g-1 wet weight (ww), followed by PCBs (1.36 ng g-1 ww), PBDEs (0.215 ng g-1 ww), and PCDD/Fs (23.0 pg g-1 ww). The concentration levels were found to be significantly higher in night heron eggs than in poultry eggs by one or two magnitude orders. Among OCP congeners, p,p'-DDE was found to be predominant in night heron eggs, with a geometric mean concentration of 15.1 ng g-1 ww. Furthermore, species-specific congener patterns in eggs suggested similar or different sources for different POPs, possibly associated with contaminated soil and parental dietary sources. Additionally, estimated daily intakes (EDIs) were used to evaluate non-carcinogenic and carcinogenic risk associated with consumption of bird eggs. Our results revealed non-negligible non-cancer and cancer risk for humans who consume wild bird eggs as a regular diet instead of poultry eggs.

Multicompartmental monitoring of legacy and currently used pesticides in a subtropical lake used as a drinking water source (Laguna del Cisne, Uruguay)

A pilot annual monitoring survey (April 2018-March 2019) was conducted to investigate the presence of pesticides in superficial water and fish in Laguna del Cisne, one of the most critical drinking water sources in Uruguay. A total of 25 pesticide residues were detected in superficial water (89.3 % of the samples). Pesticide's temporal distribution was associated with crops and livestock practices, with higher occurrences in spring and summer than in autumn and winter. The most frequent compounds in superficial water were the insecticide chlorantraniliprole, and the herbicides glyphosate (including its metabolite AMPA) and metolachlor. The levels of Organochlorine pesticide, p,p'-DDT, was in some cases two order of magnitude above the international water quality guidelines for Ambient Water Criteria. In fishes, eight different pesticides were detected, at concentrations from 1000 to 453,000 ng·kg^-1. The most frequent pesticides found were propiconazole, chlorpyrifos, and p,p'-DDE. The widespread occurrence of pesticides in fish suggests potential exposure effects on fish populations and the aquatic ecosystem. The sampling approach of this work allowed monitoring the continuous concentrations of several pesticides in surface waters and fishes to establish the influence from past and current agriculture practices in Laguna del Cisne basin. For safety measures, continuous monitoring programs must be performed in this system to prevent toxicity impacts on aquatic organisms and human health.

Organochlorine pesticides (OCPs) in freshwater resources of Pakistan: A review on occurrence, spatial distribution and associated human health and ecological risk assessment

The extensive use of organochlorine pesticides (OCPs) has resulted in the widespread contamination of different environmental matrices in Pakistan. Freshwater bodies are also prone to OCPs contamination as they receive agricultural and industrial runoff from different sources. In the present study, the data regarding OCPs' fate and distribution in freshwater resources of Pakistan was reviewed and associated risks to human and ecological health were assessed. Among all the OCPs, DDTs were more prevalent with the highest mean concentration of 2290 ng/L observed in River Ravi (Lahore and Sahiwal District). Human health risk assessment showed a higher risk to the children with high Hazard Quotient (HQ) values ranging between 4.1 × 10^-9- 295 for Aldrin. The River Ravi (Lahore and Sahiwal District), the River Sutlej (Kasur & Bahawalpur District), and the River Kabul (Nowshehra District) were categorized as high-risk water bodies based on Hazard Index (HI) and Non-Cancer Risk (CRI) index values > 10. Ecological risk assessment revealed a higher risk posed to invertebrate species from DDT exposure. In summary, this review highlights the occurrence and distribution of OCPs and their associated human health and ecological risks in freshwater bodies of Pakistan and also contributes to signifying the need for proper management and regulation of banned pesticides and future research perspectives.

Bioaccumulation of organochlorine pesticide residues (OCPs) at different growth stages of pacific white leg shrimp (Penaeus vannamei): First report on ecotoxicological and human health risk assessment

Pesticide residues (PRs) in farmed shrimps are concerning food safety risks. Globally, India is a major exporter of pacific white leg shrimp (P. vannamei). This study was undertaken to analyze PRs in the water, sediments, shrimps, and feed at different growth stages to evaluate the ecotoxicological and human health risks. PRs in the seawater and sediments ranged from not detected (ND) to 0.027 μg/L and 0.006-12.39 μg/kg, and the concentrations were within the maximum residual limits (MRLs) and sediment quality guidelines prescribed by the World Health Organization and Canadian Environment Guidelines, respectively. PRs in shrimps at three growth stages viz. Postlarvae, juvenile, and adults, ranged from ND to 0.522 μg/kg, below the MRLs set by Codex Alimentarius Commission and European Commission. Most of the PRs in water, sediments, and shrimps did not vary significantly (p > 0.05) from days of culture (DOC-01) to DOC-90. The hazard quotient (HQ) and hazard ratio (HR) were found to be < 1, indicating that consumption of shrimps has no noncarcinogenic and carcinogenic risks. PRs in shrimp feed ranged from ND to 0.777 μg/kg and were found to be below the MRLs set by EC, which confirms that the feed fed is safe for aquaculture practices and does not biomagnify in animals. The risk quotient (RQ) and toxic unit (TU) ranged from insignificant level (ISL) to 0.509 and ISL to 0.022, indicating that PRs do not pose acute and chronic ecotoxicity to aquatic organisms. The study suggested no health risk due to PRs in shrimps cultured in India and exported to the USA, China, and Japan. However, regular monitoring of PRs is recommended to maintain a sustainable ecosystem.

Halogenated organic pollutants (HOPs) in marine fish from the Beibu Gulf, South China Sea: Levels, distribution, and health risk assessment

Six marine fish species, collected from the Beibu Gulf were statistically analyzed for polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and dichlorodiphenyltrichloroethanes (DDTs). The concentrations of ∑₁₄PBDEs, ∑₂₆PCBs, and ∑₆DDTs ranged from 11.8-1431, 8.74-495, and 9.47-1263 ng g^-1 lipid weight (lw), respectively. In general, PBDEs were the predominant halogenated organic pollutants (HOPs) in the Beibu Gulf. The homologues profiles of Mugil cephalus and Trichiurus nanhaiensis differed from other four species. For example, the contributions of deca-BDEs in M. cephalus (14 %) and T. nanhaiensis (1 %) were lower than other four species (56 %). The ratio of (DDE + DDD)/ΣDDTs in all samples was >0.5, indicating that DDTs were mainly derived from historical residues. Intakes of HOPs through the consumption of the marine fish from the study areas might not subject residents of the coastal areas in the Beibu Gulf to health risks.

Source and Distribution of Emerging and Legacy Persistent Organic Pollutants in the Basins of the Eastern Indian Ocean

Persistent organic pollutants (POPs) have received significant and ongoing attention. To establish favorable regulatory policies, it is vital to investigate the occurrence, source, and budgets of POPs worldwide. POPs including phthalic acid esters (PAEs), organophosphate esters (OPEs), brominated flame retardants (BFRs), and highly chlorinated flame retardants (HFRs) have not yet been examined in the Eastern Indian Ocean (EIO). In this study, the distribution of POPs has been investigated from surface sediments with the depth of 4369-5742 m in the Central Indian Ocean Basin (CIOB) and Wharton Basin (WB) of EIO. The average (±SD) concentrations of ∑₁₁PAEs, ∑₁₁OPEs, ∑₄ BFRs, and ∑₅HFRs were 1202.0 ± 274.36 ng g^-1 dw, 15.3 ± 7.23 ng g^-1 dw, 327.6 ± 211.74 pg g^-1 dw, and 7.9 ± 7.45 pg g^-1 dw, respectively. The high abundance of low-molecular-weight (LMW) PAEs, chlorinated OPEs, LMW BDEs, and anti-Dechlorane Plus indicated the pollution characteristics in the EIO. Correlation analysis demonstrated that LMW compounds may be derived from the high-molecular-weight compounds. The monsoon circulation, currents, and Antarctic Bottom Water may be the main drivers. POP accumulation rate, depositional flux, and mass inventory in the Indian Ocean were also estimated.

Soil-air partitioning of semivolatile organic compounds in the Lesser Himalaya region: Influence of soil organic matter, atmospheric transport processes and secondary emissions

After decades of imposed regulations about reducing the primary emissions of persistent organic pollutants (POPs), these pollutants are still present in the environment. Soils are important repositories of such persistent semivolatile organic contaminants (SVOCs), and it is assumed that SVOCs sequestered in these reservoirs are being re-mobilized due to anthropogenic influence. In this study, concentrations of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in soil and air, their fugacities, fluxes and the soil-air partition coefficient (K_SA) were determined for three different land cover types (glacial, remote/mountainous and urban) of the Lesser Himalayan Region (LHR). The concentrations of OCPs, PCBs and PBDEs in soils and air ranged between 0.01 and 2.8, 0.81-4.8, 0.089-0.75 ng g^-1; 0.2-106, 0.027-182, and 0.011-7.26 pg m^-3, respectively. The levels of SVOCs in the soil were correlated with soil organic matter (SOM) indicating that SOM is a substrate for the organic pollutants in soils. The Clausius-Clapeyron plots between ln P and inverse of temperature (1000/T) suggested that long range atmospheric transport was the major input source of PBDEs and higher chlorinated PCBs over the LHR. The uneven and wide distribution of local sources in LHR and up-slope enrichment of SVOCs explained the spatial variability and altitudinal patterns. The soils near mountain and urban lakes act as local sinks of SVOCs such as β-HCH, pp΄-DDT, CB-28, -118, -153, BDE-47, -99, and -154, with soil-air exchange fluxes tending more toward deposition. However, the soils near glacial lakes acted as local sources of more volatile congeners of α-HCH, γ-HCH, op'-DDT, pp'-DDE and lower to medium chlorinated PCBs such as CB-18, -28, -53, -42 and BDE-47, -99, with soil-air exchange tending more toward volatilization flux.

Persistent organic pollutants: The trade-off between potential risks and sustainable remediation methods

Persistent Organic Pollutants (POPs) have become a very serious issue for the environment because of their toxicity, resistance to conventional degradation mechanisms, and capacity to bioconcentrate, bioaccumulate and biomagnify. In this review article, the safety, regulatory, and remediation aspects of POPs including aromatic, chlorinated, pesticides, brominated, and fluorinated compounds, are discussed. Industrial and agricultural activities are identified as the main sources of these harmful chemicals, which are released to air, soil and water, impacting on social and economic development of society at a global scale. The main types of POPs are presented, illustrating their effects on wildlife and human beings, as well as the ways in which they contaminate the food chain. Some of the most promising and innovative technologies developed for the removal of POPs from water are discussed, contrasting their advantages and disadvantages with those of more conventional treatment processes. The promising methods presented in this work include bioremediation, advanced oxidation, ionizing radiation, and nanotechnology. Finally, some alternatives to define more efficient approaches to overcome the impacts that POPs cause in the hydric sources are pointed out. These alternatives include the formulation of policies, regulations and custom-made legislation for controlling the use of these pollutants.