In 2004,ammonia concentration in raw water of Sitalakhya River at the eastern periphery of Dhaka was found higher than the expected rate of 4 mg/Lforecasted in feasibility studies,with a value of about 8 mg/L, which could not be removed by conventional treatment chain employed at Dhaka, hence, recentlyan ammonia removal plant has been constructed. This important background has ledto the current study on ammonia, a single quality parameter to understand the trend of deterioration, its probable causes, and the probable remedy.Water samples have been collected and tested for ammonia for a period of fifteen years, from 2002 to 2017, mostly in the laboratory of the existing plant. Ammonia levels have been found generally below 4 mg NH4-N/L in the wet season,though during the dry season they rise up to 20 mg NH4-N/L (sometimes more). The maximum and average values of concentration follow a more or less similar pattern with time, withboth average and maximum values, increasing around 1 mg/L annually,suggesting a similar trend in future which will make the existing treatment process inadequate. This needs attention in terms of both regulatory measures and proactive strategies on how to handle the resulting future challenges.

Coastal zone is of great importance in the provision of various valuable ecosystem services. However, it is also sensitive and vulnerable to environmental changes due to high human populations and interactions between the land and ocean. Major threats of pollution from over enrichment of nutrients, increasing metals and persistent organic pollutants (POPs), and climate change have led to severe ecological degradation in the coastal zone, while few studies have focused on the combined impacts of pollution and climate change on the coastal ecosystems at the global level. A global overview of nutrients, metals, POPs, and major environmental changes due to climate change and their impacts on coastal ecosystems was carried out in this study. Coasts of the Eastern Atlantic and Western Pacific were hotspots of concentrations of several pollutants, and mostly affected by warming climate. These hotspots shared the same features of large populations, heavy industry and (semi-) closed sea. Estimation of coastal ocean capital, integrated management of land-ocean interaction in the coastal zone, enhancement of integrated global observation system, and coastal ecosystem-based management can play effective roles in promoting sustainable management of coastal marine ecosystems. Enhanced management from the perspective of mitigating pollution and climate change was proposed.

Urban water pollution poses risks of waterborne infectious diseases. Therefore, in order to improve urban liveability, effective pollution mitigation strategies are required underpinned by predictions generated using water quality models. However, the lack of reliability in current modelling practices detrimentally impacts planning and management decision making. This research study adopted a novel approach in the form of Bayesian Networks to model urban water quality to better investigate the factors that influence risks to human health. The application of Bayesian Networks was found to enhance the integration of quantitative and qualitative spatially distributed data for analysing the influence of environmental and anthropogenic factors using three surrogate indicators of human health risk, namely, turbidity, total nitrogen and fats/oils. Expert knowledge was found to be of critical importance in assessing the interdependent relationships between health risk indicators and influential factors. The spatial variability maps of health risk indicators developed enabled the initial identification of high risk areas in which flooding was found to be the most significant influential factor in relation to human health risk. Surprisingly, population density was found to be less significant in influencing health risk indicators. These high risk areas in turn can be subjected to more in-depth investigations instead of the entire region, saving time and resources. It was evident that decision making in relation to the design of pollution mitigation strategies needs to account for the impact of landscape characteristics on water quality, which can be related to risk to human health.

Substantial evidence has linked short-term exposure to ambient fine particulate matter (PM2.5) with increased cardiovascular mortality, however, the specific chemical constituent and emission source responsible for this effect remained largely unclear. A time series Poisson model was employed to quantify the association of cardiovascular mortality with two sets of shipping pollution emission: nickel (Ni), vanadium (V) (the indices of shipping emission) and estimated shipping emission using a source apportionment approach in Guangzhou, China in 2014. We observed that Ni, V, and estimated shipping emission in PM2.5 were associated with increased cardiovascular mortality, an inter-quartile range (IQR) increase in lag2 Ni was associated with 4.60% (95% CI: 0.14%, 9.26%) increase in overall cardiovascular mortality, and 13.35% (95% CI: 5.54%, 21.75%) increase in cerebrovascular mortality; each IQR increase of lag1 V was correlated with 6.01% (95% CI: 1.83%, 10.37%) increase in overall cardiovascular mortality, and 11.02% (95% CI: 3.15%, 19.49%) increase in cerebrovascular mortality; and each IQR increase in lag1 shipping emission was associated with 5.55% (95% CI: 0.78%, 10.54%) increase in overall cardiovascular mortality, and 10.39% (95% CI: 1.43%, 20.14%) increase in cerebrovascular mortality. The results remained robust to adjustment for PM2.5 mass and gaseous air pollutants. This study suggests that shipping emission is an important detrimental factor of cardiovascular mortality, and should be emphasized in air pollution control and management in order to protect the public health in Guangzhou, China.

For human health benefits it is crucial to see if carcinogenic air pollutants like polycyclic aromatic hydrocarbons (PAHs) are reduced accordingly along with the control of the criteria pollutants including fine particles (PM₂.₅). A number of studies documented that enhanced temporary emission control during the 2014 Asia-Pacific Economic Cooperation summit (APEC) in Beijing resulted in substantial drops of observed ambient PM₂.₅, as well as PAHs, in urban areas of Beijing, yet it is not clear whether PM₂.₅-bound PAHs in the rural areas were also lowered during the APEC. Here filter-based PM₂.₅ samples were collected at a rural site in northeast of Beijing, and analyzed for 25 PAHs before (Oct. 27-Nov. 2, 2014), during (Nov. 3–12, 2014) and after (Nov. 13, 2014–Jan. 14, 2015) the APEC. Observed concentrations of PM₂.₅, OC and EC during the APEC dropped by about 30%, however, average PM₂.₅-bound PAHs and their incremental lifetime cancer risk (ILCR), 25.65 ng/m³ and 3.2 × 10⁻⁴, remained almost unchanged when compared to that of 25.48 ng/m³ and 3.5 × 10⁻⁴, respectively, before the APEC. After the APEC with the start of wintertime central heating in urban Beijing on Nov. 15, 2014, average total concentration of PAHs and their ILCR highly elevated and reached 118.25 ng/m³ and 1.5 × 10⁻³, respectively. Source apportioning by positive matrix factorization (PMF) revealed that coal combustion was the largest source that contributed 63.2% (16.1 ng/m³), 78.5% (20.1 ng/m³) and 56.1% (66.3 ng/m³) to the total PAHs before, during and after the APEC, respectively. Uncontrolled residential coal use during the APEC was found to be the reason for unabated levels of PAHs, and the largely aggravated PAHs after the APEC was resulted from increased coal consumption for wintertime residential heating. Our results suggested reducing emission from residential coal combustion is crucial to mitigate carcinogenic PAHs in ambient air, especially in rural areas.

A winter air pollution episode was observed in Hangzhou, South China, during the Second World Internet Conference, 2015. To study the pollution characteristics and underlying causes, the Weather Research and Forecasting with Chemistry model was used to simulate the spatial and temporal evolution of the pollution episode from December 8 to 19, 2015. In addition to scenario simulations, analysis of the atmospheric trajectory and synoptic weather conditions were also performed. The results demonstrated that control measures implemented during the week preceding the conference reduced the fine particulate matter (PM2.5) pollution level to some extent, with a decline in the total PM2.5 concentration in Hangzhou of 15% (7%–25% daily). Pollutant long-range transport, which occurred due to a southward intrusion of strong cold air driven by the Siberia High, led to severe pollution in Hangzhou on December 15, 2015, accounting for 85% of the PM2.5 concentration. This study provides new insights into the challenge of winter pollution prevention in Hangzhou. For adequate pollution prevention, more regional collaborations should be fostered when creating policies for northern China.

Complexity of anthropogenic influences on coastal ecosystems necessitates use of an integrated assessment strategy for effective interpretation and subsequent management. In this study a multiple lines of evidence (LOE) approach for sediment assessment, that combined use of chemistry, toxicity, and benthic community structure in the sediment quality triad was used to assess spatiotemporal changes and potential risks of persistent toxic substances (PTSs) in sediments of Masan Bay highlighting “long-term changes” between 1998 and 2014. Specific target objectives encompassed sedimentary PTSs (PAHs, alkylphenols (APs), and styrene oligomers), potential aryl hydrocarbon receptor (AhR; H4IIE-luc assay)- and estrogen receptor (ER; MVLN assay)-mediated activities, and finally several ecological quality (EcoQ) indices of benthic community structure. Concentrations of target PTSs in Masan Bay sediments were generally less by half in 2014 compared to those measured in 1998. Second, AhR-mediated potencies in sediments also decreased during this time interval, whereas ER-mediated potencies increased (+3790%), indicating that there has been substantial ongoing, input of ER agonists over the past 16 years. Potency balance analysis revealed that only 3% and 22% of the AhR- and ER-mediated potencies could be explained by identified known chemicals, such as PAHs and APs, respectively. This result indicated that non-targeted AhR and ER agonists had a considerable presence in the sediments over time. Third, EcoQ indices tended to reflect PTSs contamination in the region. Finally, ratio-to-mean values obtained from the aforementioned three LOEs indicated that quality of sediments from the outer region of the bay had recovery more during the period of 16-years than did the inner region. Overall, the results showed that even with the progress supported by recent efforts from the Korean governmental pollution control, PTSs remain a threat to local ecosystem, especially in the inner region of Masan Bay.

To meet the increasing global energy demand, expanding exploration for oil and gas reserves as well as associated drilling activities are expected in the Arctic-boreal region where sponge aggregations contribute to up to 90% of benthic biomass. These deep-water sponges along with their microbial endobionts play key roles in the nitrogen cycling in Arctic-boreal ecosystems. This study aimed to investigate the effects of drilling discharges and associated sediment resuspension events on net fluxes of oxygen, ammonium, nitrate and nitrite in three common deep-water sponge species in the form of explants. Sponges were exposed to suspended bentonite and barite, the primary particulate compounds in drilling waste, as well as suspended natural sediment particles for a period of 33 days (on average 10 mg L−1 for 12 h day−1). The exposure period was followed by a pollution abatement period for a further 33 days. No sponge mortality was observed during the experiment. However, exposure to these particles, especially to barite, led to reduced oxygen consumption by up to 33% that was linearly correlated with reduced nitrite/nitrate release by the sponges. The changes in net fluxes were accompanied by decreased tissue oxygenation by up to 54% within the sponges. These findings reveal the effects of fine particles on sponge metabolic processes by reducing aerobic respiration and microbial nitrification, and possibly by favouring anaerobic processes such as microbial denitrification. Most of the sponge responses recovered to their control levels upon the pollution abatement period, but the effects caused by barite may not be reversible. Our findings provide the first insight into the ecological consequences of oil and gas drilling activities on sponge-mediated nitrogen cycling in the Arctic-boreal region.

PM2.5 pollution is an environmental issue caused by multiple natural and socioeconomic factors, presenting with significant spatial disparities across mainland China. However, the determinant power of natural and socioeconomic factors and their interactive impact on PM2.5 pollution is still unclear. In the study, the GeogDetector method was used to quantify nonlinear associations between PM2.5 and potential factors. This study found that natural factors, including ecological environments and climate, were more influential than socioeconomic factors, and climate was the predominant factor (q = 0.56) in influencing PM2.5 pollution. Among all interactions of the six influencing factors, the interaction of industry and climate had the largest influence (q = 0.66). Two recognized major contaminated areas were the Tarim Basin in the northwest region and the eastern plain region; the former was mainly influenced by the warm temperate arid climate and desert, and the latter was mainly influenced by the warm temperate semi-humid climate and multiple socioeconomic factors. The findings provided an interpretation of the influencing mechanisms of PM2.5 pollution, which can contribute to more specific policies aimed at successful PM2.5 pollution control and abatement.

Activated sludge (AS) has been regarded as the main driver in the removal of organic pollutants such as pesticides due to a high diversity and abundance of microorganisms. However, little is known about the biodegradation genes (BDGs) and pesticide degradation genes (PDGs) harbored in the AS from wastewater treatment plants (WWTPs). In this study, we explored the bacterial communities and BDGs/PDGs in the AS from five WWTPs affiliated with pesticide factories across four consecutive seasons based on high-throughput sequencing. The AS in pesticide WWTPs exhibited unique bacterial taxa at the genus level. Furthermore, a total of 17 BDGs and 68 PDGs were explored with a corresponding average relative abundance of 0.002–0.046% and 2.078–7.143% in each AS sample, respectively, and some BDGs/PDGs clusters were also identified in the AS. The bacterial communities and BDGs/PDGs were season-dependent, and the total variations of 50.4% and 76.8% were jointly explained by environmental variables (pesticide types, wastewater characteristics, and temperature). In addition, network analysis and distribution patterns suggested that the potential hosts of BDGs/PDGs were Thauera, Stenotrophomonas, Mycobacterium, Hyphomicrobium, Allochromatium, Ralstonia, and Dechloromonas. Our findings demonstrated the linkages of bacterial communities and BDGs/PDGs in the AS, and depended on the seasons and the pesticide wastewater characteristics.