Marine debris has become a major form of pollution and a serious ecosystem health concern. The present study evaluates the accumulation, origin, and fate of debris in intertidal coral habitats of Mumbai-one of the world's highly populated coastal cities on the west coast of India. Predominantly, seven hermatypic coral species belonging to seven genera and five families were identified and mainly represented by Pseudosidastrea, Porites, and Bernardpora. In terms of number, the mean density of marine debris was 1.60 ± 0.13 SE items/m², which is higher than the global average. The mean density of plastic debris was 1.46 ± 0.14 SE items/m². Approximately 9% of total coral colonies were in physical contact with debris, and 22% of these colonies showed visible signs of partial bleaching. Single use plastic bags and wrappers were dominant plastic debris. The study area was characterized as ‘very poor cleanliness’ according to the Beach Quality Indexes, which include the Clean Coast Index, General Index, and Hazardous Items Index. The numerical model indicates the influence of river discharge and probable areas of plastic accumulation with high tidal currents in this region, maneuvering the spatial advection of litter in the nearshore areas. Combined analysis of ground-truthing and model simulation implies that the possible contributing sources of litter were representatives of land-based and sea-originated. The overall results point to increasing anthropogenic stressors threatening coastal coral communities, including marine debris pollution. It is advocated to adopt an integrated coastal zone management approach supported by coordinated policy frameworks could guide the mitigation of the debris footprint in coastal environments.

Contribution of liquid water content (LWC) to the levels of the carcinogenic particulate nitro(so) compounds and the chemistry affecting LWC were investigated based on the observation of seven nitrosamines and two nitramines in rural (Seosan) and urban (Seoul) area in South Korea during October 2019 and a model simulation. The concentrations of both the total nitrosamines and nitramines were higher in Seosan (12.48 ± 16.12 ng/m³ and 0.65 ± 0.71 ng/m³, respectively) than Seoul (7.41 ± 13.59 ng/m³ and 0.24 ± 0.15 ng/m³, respectively). The estimated LWC using a thermodynamic model in Seosan (12.92 ± 9.77 μg/m³) was higher than that in Seoul (6.20 ± 5.35 μg/m³) mainly due to higher relative humidity (75 ± 9% (Seosan); 62 ± 10% (Seoul)) and higher concentrations of free ammonia (0.13 ± 0.09 μmol/m³ (Seosan); 0.08 ± 0.01 μmol/m³ (Seoul)) and total nitric acid (0.09 ± 0.07 μmol/m³ (Seosan); 0.04 ± 0.02 μmol/m³ (Seoul)) in Seosan while neither fog nor rain occurred during the sampling period. The relatively high concentrations of the particulate nitrosamines (>30 ng/m³) only observed probably due to the higher LWC (>10 μg/m³) in Seosan. It implies that aqueous phase reactions involving NO₂ and/or uptake from the gas phase enhanced by LWC could be promoted in Seosan. Strong correlation between the concentrations of nitrosodi-methylamine (NDMA), an example of nitrosamines, simulated by a kinetic box model including the aqueous phase reactions and the measured concentration of NDMA in Seosan (R = 0.77; 0.37 (Seoul)) indicates that the aqueous phase reactions dominantly enhanced the NDMA concentrations in Seosan. On the other hand, it is estimated that the formation of nitrosamines by aqueous phase reaction was not significant due to the relatively lower LWC in Seoul compared to that in Seosan. Furthermore, it is presumed that nitramines are mostly emitted from the primary emission sources. This study implies that the concentration of the particulate nitrosamines can be promoted by aqueous phase reaction enhanced by LWC.

Environmental exposure to 4-nonylphenol (4-NP) is extensive, and studies related to human risk assessment must continue. Especially, prediction of toxicodynamics (TDs) related to reproductive toxicity in males is very important in risk-level assessment and management of 4-NP. This study aimed to develop a physiologically-based-toxicokinetic-toxicodynamic (PBTK-TD) model that added a TD prostate model to the previously reported 4-n-nonylphenol (4-n-NP) physiologically-based-pharmacokinetic (PBPK) model. Modeling was performed under the assumption of similar TKs between 4-n-NP and 4-NP because TK experiments on 4-NP, a random-mixture, are practically difficult. This study was very important to quantitatively predict the TKs and TDs of 4-NP by age at exposure using an advanced PBTK-TD model that reflected physiological-changes according to age. TD-modeling was performed based on the reported toxic effects of 4-NP on RWPE-1 cells, a human-prostate-epithelial-cell-line. Through a meta-analysis of reported human physiological data, body weight, tissue volume, and blood flow rate patterns according to age were mathematically modeled. These relationships were reflected in the PBTK-TD model for 4-NP so that the 4-NP TK and TD changes according to age and their differences could be confirmed. Differences in TK and TD parameters of 4-NP at various ages were not large, within 3.61-fold. Point-of-departure (POD) and reference-doses for each age estimated using the model varied as 426.37–795.24 and 42.64–79.52 μg/kg/day, but the differences (in POD or reference doses between ages) were not large, at less than 1.87-times. The PBTK-TD model simulation predicted that even a 100-fold 4-NP PODₘₐₙ dose would not have large toxicity to the prostate. With a focus on TDs, the predicted maximum possible exposure of 4-NP was as high as 6.06–23.60 mg/kg/day. Several toxicity-related values estimated by the dose-response curve were higher than those calculated, depending upon the PK or TK, which would be useful as a new exposure limit for prostate toxicity of 4-NP.

Reservoirs located in middle and high latitudes freeze for months in winter, where the accumulation characteristics of pollutants are changed by superimposed influence of salt exclusion from ice on the surface and pollution release from sediments at the bottom. Taking total nitrogen (TN) of Biliuhe reservoir in Northeast China as an example, we developed a model to simulate TN accumulation characteristics influenced by ice and sediments during the freezing period (NACISF), and quantified contributions of TN from ice and sediments. Model parameters of ice and sediments were determined by laboratory freeze-up simulation experiment and sediment release flux simulation experiment, and water quality data were obtained from field investigations. Results showed that the annual average amount of TN input during the ice-covered period from 2015 to 2020 was 220.77 t, the output was 400.11 t, and the accumulated amount was 589.52 t. TN excluded from ice and released from sediments contributed 8.12% and 7.17% of the total TN inputs in winter, respectively. Analysis showed that the TN excluded from ice was positively correlated with ice thickness and initial TN concentration. The maximum ice thickness of Biliuhe reservoir had a 13 year cyclic feature, and the proportion of TN excluded from ice to the total TN inputs in different periods ranged from 10.68% to 17.30% (mean 13.18%). Meanwhile, TN accumulated seasonally as summer > autumn > winter > spring. The TN exclusion effect in 2050 would be weakened when considering the combined effects of climate change and human activities, with a reduction of about 40.85% compared to the current. It is concluded that the NACISF model took into account the influences of both ice and sediments, which provided a detailed understanding of the accumulation characteristics of TN during freezing period, and had important reference significance for water quality management in winter.

South Korea has experienced a rapid increase in ozone concentrations in surface air together with China for decades. Here we use a 3-D global chemical transport model, GEOS-Chem nested over East Asia (110 E - 140 E, 20 N–50 N) at 0.25° × 0.3125° resolution, to examine locally controllable (domestic anthropogenic) versus uncontrollable (background) contributions to ozone air quality at the national scale for 2016. We conducted model simulations for representative months of each season: January, April, July, and October for winter, spring, summer, and fall and performed extensive model evaluation by comparing simulated ozone with observations from satellite and surface networks. The model appears to reproduce observed spatial and temporal ozone variations, showing correlation coefficients (0.40–0.87) against each observation dataset. Seasonal mean ozone concentrations in the model are the highest in spring (39.3 ± 10.3 ppb), followed by summer (38.3 ± 14.4 ppb), fall (31.2 ± 9.8 ppb), and winter (24.5 ± 7.9 ppb), which is consistent with that of surface observations. Background ozone concentrations obtained from a sensitivity model simulation with no domestic anthropogenic emissions show a different seasonal variation in South Korea, showing the highest value in spring (46.9 ± 3.4 ppb) followed by fall (38.2 ± 3.7 ppb), winter (33.0 ± 1.9 ppb), and summer (32.1 ± 6.7 ppb). Except for summer, when the photochemical formation is dominant, the background ozone concentrations are higher than the seasonal ozone concentrations in the model, indicating that the domestic anthropogenic emissions play a role as ozone loss via NOₓ titration throughout the year. Ozone air quality in South Korea is determined mainly by year-round regional background contributions (peak in spring) with summertime domestic ozone formation by increased biogenic VOCs emissions with persistent NOₓ emissions throughout the year. The domestic NOₓ emissions reduce MDA8 ozone around large cities (Seoul and Busan) and hardly increase MDA8 in other regions in spring, but it increases MDA8 across the country in summer. Therefore, NOₓ reduction can be effective in control of MDA8 ozone in summer, but it can have rather countereffect in spring.

On-road remote sensing technology measures the concentration ratios of pollutants over CO₂ in the exhaust plume in half a second when a vehicle passes by a measurement site, providing a rapid, non-intrusive and economic tool for vehicle emissions monitoring and control. A key assumption in such measurement is that the emission ratios are constant for a given plume. However, there is a lack of study on this assumption, whose validity could be affected by a number of factors, especially the engine operating conditions and turbulence. To guide the development of the next-generation remote sensing system, this study is conducted to investigate the effects of various factors on the emissions dispersion process in the vehicle near-wake region and their effects on remote sensing measurement. The emissions dispersion process is modelled using Large Eddy Simulation (LES). The studied factors include the height of the remote sensing beam, vehicle speed, acceleration and side wind. The results show that the measurable CO₂ and NO exhaust plumes are relatively short at 30 km/h cruising speed, indicating that a large percentage of remote sensing readings within the measurement duration (0.5 s) are below the sensor detection limit which would distort the derived emission ratio. In addition, the valid measurement region of NO/CO₂ emission ratio is even shorter than the measurable plume and is at the tailpipe height. The effect of vehicle speed (30–90 km/h) on the measurable plume length is insignificant. Under deceleration condition, the length of the valid NO/CO₂ measurement region is shorter than under cruising and acceleration conditions. Side winds from the far-tailpipe direction have a significant effect on remote sensing measurements. The implications of these findings are discussed and possible solutions to improve the accuracy of remote sensing measurement are proposed.

Dibutyl phthalate (DBP) is widely used as plasticizer and has been detected in the environment, posing a threat to animal health. However, the effects of DBP on agricultural microbiomes are not known. In this study, DBP levels in black soil were evaluated, and the impact of DBP contamination on the uptake and metabolism of sugars in microbes was assessed by glucose absorption tests, metaproteomics, metabolomics, enzyme activity assays and computational simulation analysis. The results indicated that DBP contamination accelerated glucose consumption and upregulated the expression of porins and periplasmic monosaccharide ATP-binding cassette (ABC) transporter solute-binding proteins (SBPs). DBP and its metabolic intermediates (carboxymuconate and butanol) may form a stable complex with sugar transporters and enhance the rigidity and stability of these proteins. Sugar metabolism resulting in the generation of ATP and reducing agent (NADPH), as well as the expression of some key enzymes (dehydrogenases) were also upregulated by DBP treatment. Moreover, a diverse bacterial community appears to utilize sugar, suggesting that there are widespread effects of DBP contamination on soil microbial ecosystems. The results of this study provide a theoretical basis for investigating the toxicological effects of DBP on microbes in black soil.

As one of the most cost-effective and sustainable methods for contaminants' removal, sequestration and/or detoxification, phytoremediation has already captured comprehensive attention worldwide. Nevertheless, the accurate effects of various spatial pattern in enhancing phytoremediation efficiency is not yet clear, especially for the polluted mining areas. This study designed nine planting patterns (monocropping, double intercropping and triple intercropping) of three indigenous plant species (Setaria viridis (L.), Echinochloa crus-galli (L.) and Phragmites australis (Cav.) Trin. ex Steud.) to further explore the effects of plants spatial pattern on phytoremediation efficiency. Considering the uncertainties of the residual contaminants' concentration (RCC) caused by soil anisotropy, permeability and land types, the interval transformation was introduced into the plant uptake model to simulate the remediation efficiency. Then multi-criteria decision analysis (MCDA) were applied to optimal the planting patterns, with the help of criteria of (a) the amount of heavy metal absorption; (b) the concentration of residual contaminant in soil; (c) root tolerance of heavy metals; (d) the total investment cost. Results showed that (1) the highest concentrations of Zn, Cd, and Pb of the polluted area were 7320.02, 14.30, 1650.51 mg kg⁻¹ (2) During the 180 days simulation, the highest RMSE of residue trace metals in soil are 3.02(Zn), 2.67(Pb), 2.89(Cd), respectively. (3) The result of IMCDA shows that the planting patterns of Setaria viridis, Echinochloa crus-galli and Phragmites australis in alternative a9 (269 mg kg⁻¹ year⁻¹) had the highest absorption rate of heavy metals compared with a7 (235 mg kg⁻¹ year⁻¹) and a2 (240 mg kg⁻¹ year⁻¹). After 20 years of remediation, the simulated RCC in a9 is far below the national standard, and the root toxicity is 0.12 (EC ≤ EC₂₀). In general, the optimal alternative derived from interval residual contaminant concentration can effectively express the dynamic of contaminant distribution and then can be effectively employed to evaluate the sustainable remediation methods.

Alternative transportation fuels (ATFs) can reduce air pollution. However, the influence of conventional fuels—diesel and gasoline, and particularly ATFs on photochemical air pollution is not well-characterized, limiting assessments of ATFs and air quality. This is mainly due to frequent use of lumped chemical mechanisms by related atmospheric modeling. Here we hypothesized that applying a chemical mechanism that is specifically developed according to both emission fractions and photochemical ozone creation potential of volatile organic compounds (VOCs) is key to gaining reliable insights into the impact of transportation fuels on photochemistry. We used a heterogeneous chemical mechanism with 927 reactions and relatively detailed emission inventories to specifically meet the requirements for reliable simulation of the effect of exhaust emissions from vehicles fueled by selected model fuels—diesel, gasoline, and mixtures of 15% gasoline with 85% ethanol (E85) or 85% methanol (M85)—on photochemistry. These dispersion-box model simulations revealed a strong influence of atmospheric background balance between VOCs and nitrogen oxides (NOX = [NO] + [NO2]) on the impact of exhaust emissions on photochemistry, with higher tendency toward ozone (O3) formation or destruction for more VOC-limited or NOX-limited conditions, respectively. Accordingly, higher [NOX]/[VOC] exhaust emission, such as from diesel and M85, resulted in lower O3, not only locally but also downwind of the emission. This offers a new perspective and measure for transportation fuel assessment. Rapid conversion of O3 to hydroxyl and hydroperoxyl radicals downwind of the exhaust emission indicates the importance of simulating the impact of road transportation on photochemistry at high spatial and temporal resolution. Peroxyacetyl nitrate formation was more sensitive to VOC emission under VOC-limited conditions than to NOX emission under NOX-limited conditions. Secondary formaldehyde dominated over primary emitted formaldehyde several minutes after emission. These findings should be verified using a 3D modeling study under varying meteorological conditions.

Tools to predict environmental fate processes during remediation of persistent organic pollutants (POPs) in soil are desperately needed since they can elucidate the overall behavior of the chemical and help to improve the remediation process. A dynamic multimedia fate model (SoilPlusVeg) was further developed and improved to account for rhizoremediation processes. The resulting model was used to predict Polychlorinated Biphenyl (PCB) fate in a highly contaminated agricultural field (1089 ng/g d.w.) treated with tall fescue (Festuca arundinacea), a promising plant species for the remediation of contaminated soils. The model simulations allowed to calculate the rhizoremediation time (about 90 years), given the available rhizoremediation half-lives and the levels and fingerprints of the PCB congeners, to reach the legal threshold, to show the relevance of the loss processes from soil (in order of importance: degradation, infiltration, volatilization, etc.) and their dependence on meteorological and environmental dynamics (temperature, rainfall, DOC concentrations). The simulations showed that the effective persistence of PCBs in soil is deeply influenced by the seasonal variability. The model also allowed to evaluate the role of DOC as a possible enhancer of PCB degradation as a microorganism “spoon feeder” of PCBs in the soil solution. Additionally, we preliminary predicted how the contribution of PCB metabolites could modify the PCB fingerprint and their final total concentrations. This shows that the SoilPlusVeg model could be used in selecting the best choices for a sustainable rhizoremediation of a POP contaminated site.