Agriculture is one of major emission sources of nitrous oxide (N₂O), an important greenhouse gas dominating stratospheric ozone destruction. However, indirect N₂O emissions from agriculture watershed water surfaces are poorly understood. Here, surface-dissolved N₂O concentration in water bodies of the agricultural watershed in Eastern China, one of the most intensive agricultural regions, was measured over a two-year period. Results showed that the dissolved N₂O concentrations varied in samples taken from different water types, and the annual mean N₂O concentrations for rivers, ponds, reservoir, and ditches were 30 ± 18, 19 ± 7, 16 ± 5 and 58 ± 69 nmol L⁻¹, respectively. The N₂O concentrations can be best predicted by the NO3−-N concentrations in rivers and by the NH4+-N concentrations in ponds. Heavy precipitation induced hot moments of riverine N₂O emissions were observed during farming season. Upstream waters are hot spots, in which the N₂O production rates were two times greater than in non-hotspot locations. The modeled watershed indirect N₂O emission rates were comparable to direct emission from fertilized soil. A rough estimate suggests that indirect N₂O emissions yield approximately 4% of the total N₂O emissions yield from N-fertilizer at the watershed scale. Separate emission factors (EF) established for rivers, ponds, and reservoir were 0.0013, 0.0020, and 0.0012, respectively, indicating that the IPCC (Inter-governmental Panel on Climate Change) default value of 0.0025 may overestimate the indirect N₂O emission from surface water in eastern China. EF was inversely correlated with N loading, highlighting the potential constraints in the IPCC methodology for water with a high anthropogenic N input.

Cyanobacterial blooms are of global concern due to the multiple harmful risks they pose towards aquatic ecosystem and human health. However, information on the fate of organic pollutants mediated by cyanobacterial blooms in eutrophic water remains elusive. In the present study, endocrine disruptive potentials of phytoplankton samples were evaluated throughout a year-long surveillance in a large and eutrophic freshwater lake. Severe cyanobacterial blooms persisted during our sampling campaigns. Estrogenic agonistic, anti-estrogenic, anti-androgenic, and anti-glucocorticogenic effects were observed in the phytoplankton samples using in vitro reporter gene bioassays. 27 endocrine disrupting chemicals (EDCs) of different modes of action were detected in the samples via UPLC-MS/MS system. Results from mass balance analysis indicated that the measured estrogenic activities were greater than the predicted estrogenic potencies from chemical analysis, demonstrating that chemical analysis of targeted EDCs is unable to fully explain the compounds responsible for the observed estrogenicities. Results from Spearman's correlation analysis concluded that the concentrations of ten EDCs in phytoplankton samples were negatively correlated with cyanobacterial biomass, suggesting the potential occurrence of biomass bio-dilution effects of EDCs due to the huge biomass of cyanobacteria during bloom seasons. The present study provided complementary information about the potential endocrine disruptive risks of cyanobacterial blooms, which is important for understanding and regulating EDCs in eutrophic lakes.

The imprints of fireworks displays on the adjacent water body were investigated from the perspective of cogeneration of black carbon, metals and perchlorate (ClO₄⁻). In particular, the mixing and dissipation of ClO₄⁻ were studied at Oak Lake, Lincoln, Nebraska, following fireworks displays in 2015 and 2016. Following the display, ClO₄⁻ concentration in the water increased up to 4.3 μg/L and 4.0 μg/L in 2015 and 2016, respectively. A first-order model generally provided a good fit to the measured perchlorate concentrations from which the rate of dissipation was estimated as 0.07 d⁻¹ in 2015 and 0.43 d⁻¹ in 2016. SEM images show imprints of soot and metal particles in aerosol samples. EDS analysis of the lake sediment confirmed the presence of Si, K, Ca, Zn and Ba, most of which are components of fireworks. The δ¹³C range of −7.55‰ to −9.19‰ in the lake water system closely resembles fire-generated carbon. Cogeneration of black carbon and metal with perchlorate was established, indicating that ClO₄⁻ is an excellent marker of fireworks or a burning event over all other analyzed parameters. Future microcosmic, aggregation and column-based transport studies on black carbon in the presence of perchlorate and metals under different environmental conditions will help in developing transport and fate models for perchlorate and black carbon particles.

High-density polyethylene (HDPE) is a known sorbent for non-ionic organic compounds in technical applications. Nevertheless, there is little information available describing sorption to industrial HDPE for a broad range of compounds. With a better understanding of the sorption properties of synthetic polymers, environmental risk assessment would achieve a higher degree of accuracy, especially for microplastic interactions with organic substances. Therefore, a robust methodology for the determination of sorbent properties for non-ionic organic compounds by HDPE is relevant for the understanding of molecular interactions for both technical use and environmental risk assessment.In this work, sorption properties of HDPE material used for water pipes were characterized using a poly-parameter linear free-energy relationship (ppLFER) approach. Sorption batch experiments with selected probe sorbates were carried out in a three-phase system (air/HDPE/water) covering an aqueous concentration range of at least three orders of magnitude. Sorption in the concentration range below 10⁻² of the aqueous solubility was found to be non-linear and the Freundlich model was used to account for this non-linearity. Multiple regression analysis (MRA) using the determined distribution coefficients and literature-tabulated sorbate descriptors was performed to obtain the ppLFER phase descriptors for HDPE. Sorption properties of HDPE were then derived from the ppLFER model and statistical analysis of its robustness was conducted. The derived ppLFER model described sorption more accurately than commonly used single-parameter predictions, based i.e., on log Kₒ/w. The ppLFER predicted distribution data with an error 0.5 log units smaller than the spLFERs. The ppLFER was used for a priori prediction of sorption by the characterized sorbent material. The prediction was then compared to experimental data from literature and this work and demonstrated the strength of the ppLFER, based on the training set over several orders of magnitude.

Spirocyclic tetramic acids are widely used in controlling phytophagous mite species throughout the world. the data set is incomplete and provides insufficient evidence for drawing the same conclusion for fish. To fill the gap whether these acaricides alter lipid metabolism on vertebrates, zebrafish embryos exposed to a series concentration of pesticides, the developmental effects, enzyme activities and levels of gene expression were assessed, battery of biomarker utilized by the integrated biomarker response (IBRv2) model. The 96 h-LC₅₀ of spirodiclofen, spiromesifen and spirotetramat were 0.14, 0.12 and 5.94 mg/L, respectively. Yolk sac deformity, pericardial edema, spinal curvature and tail malformation were observed. Three spirocyclic acids were unfavouring the lipid accumulation of by inhibited the acetyl-CoA carboxylase (ACC), fatty acid synthesis (FAS), fatty acid binding proteins (FABP2) and lipoprotein lipase (LPL) activity. The total cholesterol (TCHO) level significantly decreased in the 0.072 mg/L spirodiclofen group and 0.015 and 0.030 mg/L in the spiromesifen groups. No expected change in spirotetramat group on the TCHO and triglycerides (TGs) levels for any of the treatments. The mRNA levels of the genes related to lipid metabolism also significantly altered. In both spirodiclofen and spiromesifen, ACC achieved the highest scores among a battery of biomarkers using integrated biomarker response (IBRv2). The results suggest that spiromesifen was the most toxic for embryos development and spirodiclofen was the most toxic for lipid metabolism in embryos. The 0.07 mg/L of spirodiclofen, 0.05 mg/L of spiromesifen and 2.00 mg/L would cause malformation on zebrafish embryos. This study will provide new insight that fatty acid metabolism may be a suitable biomarker for the spirocyclic tetramic acids in fish species.

Urban stormwater reuse is becoming increasingly prevalent to overcome the serious urban water scarcity being experienced around the world. Therefore, the adoption of reliable approaches to minimise the human health risk posed by pollutants commonly present in urban stormwater such as heavy metals and polycyclic aromatic hydrocarbons (PAHs) is critical for safe stormwater reuse. This study collected a total of 40 pollutant build-up samples and analysed the concentrations of nine heavy metals and 15 PAH species. Based on pollutant build-up data, pollutant concentrations in stormwater were estimated through modelling. Risk assessment was conducted using an existing model developed by previous studies. The study outcomes confirmed that simply evaluating the individual pollutant concentrations based on guideline threshold values cannot comprehensively estimate the overall human health risk posed by these pollutants. Accordingly, it is recommended that the assessment of the overall human health risk should be based on the pollutant mix present as provided by the models discussed in this paper. The study has also demonstrated the practical application of a robust risk assessment model to derive the hierarchy of hazard control to provide a reliable underpinning to urban stormwater risk management. The outcomes suggest that decentralised hazard control methods such as the provision of custom designed Water Sensitive Urban Design (WSUD) measures can be implemented in priority areas with high risk from stormwater pollution based on the risk assessment undertaken. Distributed hazard control methods can be applied to reduce the generation of primary toxic pollutants, especially chromium (Cr) and heavy PAHs, through elimination and substitution measures. The percentage reduction in traffic volume required to mitigate the human health risk can be quantified through the risk models presented. The study outcomes will contribute to the development of efficient, targeted and reliable stormwater management strategies and to identify viable opportunities for stormwater reuse.

Cadmium (Cd) is a toxic heavy metal that is widely distributed in the environment. However, the mechanisms linking Cd exposure and type 2 diabetes risks are not completely elucidated. In this study, we aim to investigate the roles of C-reactive protein (CRP) on the association between urinary Cd and type 2 diabetes risk. We determined urinary Cd and plasma CRP concentrations among 3,140 adults from Wuhan-Zhuhai cohort. Dose-response relationships between urinary Cd, plasma CRP, and type 2 diabetes were explored using multivariate logistic regression and linear mixed regression models. Mediation analysis was performed to investigate the role of plasma CRP in the associations between urinary Cd and type 2 diabetes risk. With adjustment for potential confounders, the odds ratios (ORs) of type 2 diabetes showed an upward trend when urinary Cd concentration gradually increased (P trend <0.01). Significantly positive dose-response relationships were observed between urinary Cd and plasma CRP, as well as between plasma CRP and type 2 diabetes risk. Compared to those when both Cd and CRP levels were low, the adjusted ORs (95%CI) of type 2 diabetes was the highest [2.053(1.395–3.020)] in individuals with high levels of urinary Cd and plasma CRP. Mediation analysis estimated that plasma CRP mediated 4.01% of the association between urinary Cd and type 2 diabetes risk [mediating effect: OR (95%CI) = 1.019(1.002–1.057)]. Individuals with high levels of urinary Cd and plasma CRP had a much higher risk of type 2 diabetes. Plasma CRP may serve as a mediator in the association between urinary Cd and type 2 diabetes risk, providing clues for further study on the biological pathway for type 2 diabetes related to Cd exposure.

Environmental estrogens are capable of interfering with the spermatogenesis and fertility of fish. However in natural waters, these chemicals are more likely to occur as a combination rather than a single stressor. Whether and how the mixture of xenoestrogens with environmental relevant concentrations may affect fish spermatogenesis remains largely unknown. In this study, male zebrafish adults were administered to 17alpha-ethinylestradiol (EE2) and a mixture of xenoestrogens (Mix (E2, EE2, DES, 4-t-OP, 4-NP and BPA)), with the estrogenic potency equivalent to EE2. After a 60-day exposures, elevated mRNA levels of vitellogenin 1 (vtg1) and estrogen receptor 1 (esr1) in the liver of fish in both treated groups were observed. Moreover, the plasma level of E2 declined significantly in the Mix group and the ratio of 11-KT/E2 was significantly elevated in both treated groups. Consistently, the mRNA level of P450 side-chain cleavage (scc) in the EE2 group and ovarian type aromatase (cyp19a1a) in the Mix group was significantly suppressed. In addition, decreased gonadosomatic index and sperm count in the fish of Mix group were present. Furthermore, increased number of the proliferating germ cells (such as spermatogonia and spermatocytes) was observed in the fish of both groups, suggesting a stimulated germ cell proliferation and meiosis. Accordingly, both exposures significantly up-regulated the mRNA levels of genes in mitosis (cyclinb1) and meiosis (cyp26a1 in EE2 group, aldh1a2, cyp26a1, sycp3 and spo11 in Mix). In addition, decreased number of spermatozoa and increased number of TUNEL-positive signals were present in the testis of fish in the Mix group, indicating an enhanced apoptosis. Further analyses demonstrated the significant elevated expressions of tnfrsf1a and the ratio of tnfrsf1a/tnfrsf1b in the Mix group, suggesting an elevated apoptosis in the testis of fish in the Mix group via extrinsic pathway. The present study greatly extends our understanding of the underlying mechanisms of the reproductive toxicity of xenoestrogens on fish.

Microplastics are defined as plastic fragments <5 mm, and they are found in the ocean where they can impact on the ecosystem. Once released in seawater, microplastics can be internalized by organisms due to their small size, moreover they can also leach out several additives used in plastic manufacturing, such as plasticizers, flame retardants, etc., resulting toxic for biota. The aim of this study was to test the toxicity of micronized PVC products with three different colors, upon Paracentrotus lividus embryos. In particular, we assessed the effects of micronized plastics and microplastic leachates. Results showed a decrease of larval length in plutei exposed to low concentrations of micronized plastics, and a block of larval development in sea urchin embryos exposed to the highest dose. Virgin PVC polymer did not result toxic on P. lividus embryos, while an evident toxic effect due to leached substances in the medium was observed. In particular, the exposure to leachates induced a development arrest immediately after fertilization or morphological alterations in plutei. Finally, PVC products with different colors showed different toxicity, probably due to a different content and/or combination of heavy metals present in coloring agents.

Associations between single metal and fasting blood glucose (FBG) levels have been reported in previous studies. However, the association between multi-metals exposure and FBG level are little known. To assess the joints of arsenic (As), nickel (Ni), cadmium (Cd), selenium (Se), and zinc (Zn) co-exposure on FBG levels, Bayesian kernel machine regression (BKMR) statistical method was used to estimate the potential joint associations between As, Ni, Cd, Se, and Zn co-exposure and FBG levels among 1478 community-based Chinese adults from two counties, Shimen (n = 696) and Huayuan (n = 782), with different exposure profiles in Hunan province of China. The metals levels were measured in spot urine (As, Ni, and Cd) and plasma (Se and Zn) using inductively coupled plasma-mass spectrometry, respectively. The exposure levels of all the five metals were significantly higher in Shimen area (median: As = 57.76 μg/L, Cd = 2.75 μg/L, Ni = 2.73 μg/L, Se = 112.67 μg/L, Zn = 905.68 μg/L) than those in Huayuan area (As = 41.14 μg/L, Cd = 2.22 μg/L, Ni = 1.88 μg/L, Se = 65.59 μg/L, Zn = 819.18 μg/L). The BKMR analyses showed a significantly positive over-all effect of the five metals on FBG levels when metals concentrations were all above the 50th percentile while a statistically negative over-all effect when metals concentrations were all under the 50th percentile in Shimen area. However, a totally opposite over-all effect of the mixture of the five metals on FBG levels was found in Huayuan area. BKMR also revealed a non-linear exposure-effect of Zn on FBG levels in Huayuan area. In addition, interaction effects of As and Se on FBG level were observed. The relationship between single or combined metals exposure and FBG was different against different exposure profiles. Potential interaction effects of As and Se on FBG levels may exist.