Following the Deepwater Horizon (DWH) event in 2010, hydrocarbons were deposited on the continental slope in the northeastern Gulf of Mexico through marine oil snow sedimentation and flocculent accumulation (MOSSFA). The objective of this study was to test the hypothesis that benthic foraminiferal δ13C would record this depositional event. From December 2010 to August 2014, a time-series of sediment cores was collected at two impacted sites and one control site in the northeastern Gulf of Mexico. Short-lived radioisotopes (210Pb and 234Th) were employed to establish the pre-DWH, DWH, and post-DWH intervals. Benthic foraminifera (Cibicidoides spp. and Uvigerina spp.) were isolated from these intervals for δ13C measurement. A modest (0.2–0.4‰), but persistent δ13C depletion in the DWH intervals of impacted sites was observed over a two-year period. This difference was significantly beyond the pre-DWH (background) variability and demonstrated that benthic foraminiferal calcite recorded the depositional event. The longevity of the depletion in the δ13C record suggested that benthic foraminifera may have recorded the change in organic matter caused by MOSSFA from 2010 to 2012. These findings have implications for assessing the subsurface spatial distribution of the DWH MOSSFA event.

Addressing the worsening urban air quality situation in Sub-Saharan Africa (SSA) is proving increasingly difficult owing to paucity of data on air pollution levels and also, lack of local evidence on the magnitude of the associated health effects. There is therefore the urgent need to expand air quality monitoring (AQM) networks in SSA to enable the conduct of high quality epidemiologic studies to help inform policies aimed at addressing air pollution and the associated health effects. In this commentary, I explore the prospects that the proliferation of low-cost sensors in recent times holds for air pollution epidemiologic research in SSA. This commentary is timely because most SSA governments do not see investments in air pollution control that requires assembling a network of sophisticated and prohibitively expensive instrumentation for AQM as necessary for improving and protecting public health. I conclude that, in a region that is bereft of air pollution data, the growing influx of low-cost sensors represents an excellent opportunity for bridging the data gap to inform air pollution control policies and regulations for public health protection. However, it is essential that only the most promising sensor technologies that performs creditably well in the harsh environmental conditions of the region are promoted.

Air pollution in China has been very serious during the recent decades. However, few studies have investigated the effects of short-term exposure to PM2.5 and O3 on daily outpatient visits for respiratory diseases. We examined the effects of PM2.5 and O3 on the daily outpatient visits for respiratory diseases, explored the sensitivities of different population subgroups and analyzed the relative risk (RR) of PM2.5 and O3 in different seasons in Shanghai during 2013–2016. The generalized linear model (GLM) was applied to analyze the exposure-response relationship between air pollutants (daily average PM2.5 and daily maximum 8-h average O3), and daily outpatient visits due to respiratory diseases. The sensitivities of males and females at the ages of 15–60 yr-old and 60+ yr-old to the pollutants were also studied for the whole year and for the cold and warm months, respectively. Finally, the results of the single-day lagged model were compared with that of the moving average lag model. At lag 0 day, the RR of respiratory outpatients increased by 0.37% with a 10 μg/m3 increase in PM2.5. Exposure to PM2.5 (RR, 1.0047, 95% CI, 1.0032–1.0062) was more sensitive for females than for males (RR, 1.0025, 95% CI, 1.0008–1.0041), and was more sensitive for the 15-60 yr-old (RR, 1.0041, 95% CI, 1.0027–1.0055) than the 60+ yr-old age group (RR, 1.0031, 95% CI, 1.0014–1.0049). O3 was not significantly associated with respiratory outpatient visits during the warm periods, but was negatively associated during the cold periods. PM2.5 was more significantly in the cold periods than that in the warm periods. The results indicated that control of PM2.5, compared to O3, in the cold periods would be more beneficial to the respiratory health in Shanghai. In addition, the single-day lagged model underestimated the relationship between PM2.5 and O3 and outpatient visits for respiratory diseases compared to the moving average lag model.

Silver, such as silver nanoparticles (AgNPs), has been widely used in commercial products and may be released into the environment. The interaction between Ag deposition and biological systems is raising serious concerns because of one health consideration. Cetaceans, as the top predators of the oceans, may be exposed to Ag/Ag compounds and suffer negative health impacts from the deposition of these compounds in their bodies. In the present study, we utilized autometallography (AMG) to localize the Ag in the liver and kidney tissues of cetaceans and developed a model called the cetacean histological Ag assay (CHAA) to estimate the Ag concentrations in the liver and kidney tissues of cetaceans. Our results revealed that Ag was mainly located in hepatocytes, Kupffer cells and the epithelial cells of some proximal renal tubules. The tissue pattern of Ag/Ag compounds deposition in cetaceans was different from those in previous studies conducted on laboratory rats. This difference may suggest that cetaceans have a different metabolic profile of Ag, so a presumptive metabolic pathway of Ag in cetaceans is advanced. Furthermore, our results suggest that the Ag contamination in cetaceans living in the North-western Pacific Ocean is more severe than that in cetaceans living in other marine regions of the world. The level of Ag deposition in cetaceans living in the former area may have caused negative impacts on their health condition. Further investigations are warranted to study the systemic Ag distribution, the cause of death/stranding, and the infectious diseases in stranded cetaceans with different Ag concentrations for comprehensively evaluating the negative health effects caused by Ag in cetaceans.

Fine particles (PM2.5) samples, collected at Weizhou Island over the Gulf of Tonkin on a daytime and nighttime basis in the spring of 2015, were analyzed for primary and secondary organic tracers, together with organic carbon (OC), elemental carbon (EC), and stable carbon isotopic composition (δ13C) of total carbon (TC). Five organic compound classes, including saccharides, lignin/resin products, fatty acids, biogenic SOA tracers and phthalic acids, were quantified by gas chromatography/mass spectrometry (GC/MS). Levoglucosan was the most abundant organic species, indicating that the sampling site was under strong influence of biomass burning. Based on the tracer-based methods, the biomass-burning-derived fraction was estimated to be the dominant contributor to aerosol OC, accounting for 15.7% ± 11.1% and 22.2% ± 17.4% of OC in daytime and nighttime samples, respectively. In two episodes E1 and E2, organic aerosols characterized by elevated concentrations of levoglucosan as well as its isomers, sugar compounds, lignin products, high molecular weight (HMW) fatty acids and β-caryophyllinic acid, were attributed to the influence of intensive biomass burning in the northern Southeast Asia (SEA). However, the discrepancies in the ratios of levoglucosan to mannosan (L/M) and OC (L/OC) as well as the δ13C values suggest the type of biomass burning and the sources of organic aerosols in E1 and E2 were different. Hardwood and/or C4 plants were the major burning materials in E1, while burning of softwood and/or C3 plants played important role in E2. Furthermore, more complex sources and enhanced secondary contribution were found to play a part in organic aerosols in E2. This study highlights the significant influence of springtime biomass burning in the northern SEA to the organic molecular compositions of marine aerosols over the Gulf of Tonkin.

The emerging insensitive munitions compound (IMC) 3-nitro-1,2,4-triazole-5-one (NTO) is currently being used to replace conventional explosives such as 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), but the environmental fate of this increasingly widespread IMC remains poorly understood. Upon release from unexploded solid phase ordinances, NTO exhibits high aqueous solubility and, hence, potential mobilization to groundwater. Adsorption and abiotic transformation at metal oxide surfaces are possible mechanisms for natural attenuation. Here, the reactions at ferrihydrite and birnessite surfaces of NTO and its biotransformation product, 3-amino-1, 2, 4-triazol-5-one (ATO), were studied in stirred batch reactor systems at controlled pH (7.0). The study was carried out at metal oxide solid to solution ratios (SSR) of 0.15, 1.5 and 15 g kg−1. The samples were collected at various time intervals up to 3 h after reaction initiation, and analyzed using HPLC with photodiode array and mass spectrometric detection. We found no detectable adsorption or transformation of NTO upon reaction with birnessite, whereas ATO was highly susceptible to oxidation by the same mineral, showing nearly complete transformation within 5 min at 15 g kg−1 SSR to urea, CO2(g) and N2(g). The mean surface-area-normalized pseudo-first order rate constant (k) for ATO oxidation by birnessite across all SSRs was 0.05 ± 0.022 h−1 m−2, and oxidation kinetics were independent of dissolved O2 concentration. Both NTO and ATO were resistant to oxidation by ferrihydrite. However, NTO showed partial removal from solution upon reaction with ferrihydrite at 0.15 and 1.5 g kg−1 SSR and complete loss at 15 g kg−1 SSR due to strong adsorption. Conversely, ATO adsorption to ferrihydrite was much weaker than that measured for NTO.

Pollutant emissions from incomplete combustion of raw coal in low-efficiency residential heating stoves greatly contribute to winter haze in China. Semi-coke coals and improved heating stoves are expected to lower air pollutant emissions and are vigorously promoted by the Chinese government in many national and local plans. In this study, the thermal performance and air pollutant emissions from semi-coke combustion in improved heating stoves were measured in a pilot rural county and compared to the baseline of burning raw coal to quantify the mitigation potential of air pollutant emissions. A total of five stove-fuel combinations were tested, and 27 samples from 27 different volunteered households were obtained. The heating efficiency of improved stoves increased, but fuel consumption appeared higher with more useful energy output compared to traditional stoves. The emission factors of PM2.5, SO2, and CO2 of semi-coke burning in specified improved stoves were lower than the baseline of burning raw coal chunk, but no significant NOx and CO decreases were observed. The total amount of PM2.5 and SO2 emissions per household in one heating season was lower, but CO, CO2, and NOx increased when semi-coke coal and specified improved stoves were deployed. Most differences were not statistically significant due to the limited samples and large variation, indicating that further evaluation would be needed to make conclusions that could be considered for policy.

Pollutant mass fluxes are rarely measured in the laboratory, especially their turbulent component. They play a major role in the dispersion of gases in urban areas and modern mathematical models often attempt some sort of parametrisation. An experimental technique to measure mean and turbulent fluxes in an idealised urban array was developed and applied to improve our understanding of how the fluxes are distributed in a dense street canyon network. As expected, horizontal advective scalar fluxes were found to be dominant compared with the turbulent components. This is an important result because it reduces the complexity in developing parametrisations for street network models. On the other hand, vertical mean and turbulent fluxes appear to be approximately of the same order of magnitude. Building height variability does not appear to affect the exchange process significantly, while the presence of isolated taller buildings upwind of the area of interest does. One of the most interesting results, again, is the fact that even very simple and regular geometries lead to complex advective patterns at intersections: parametrisations derived from measurements in simpler geometries are unlikely to capture the full complexity of a real urban area.

Microplastics, which are plastic debris with a particle diameter of less than 5 mm, have attracted growing attention in recent years. Its widespread distributions in a variety of habitats have urged scientists to understand deeper regarding their potential impact on the marine living resources. Most studies on microplastics hitherto are focused on the marine environment, and research on risk assessment methodology is still limited. To understand the distribution of microplastics in urban rivers, this study investigated river sediments in Shanghai, the largest urban area in China. Seven sites were sampled to ensure maximum coverage of the city's central districts, and a tidal flat was also included to compare with river samples. Density separation, microscopic inspection and μ-FT-IR analysis were conducted to analyze the characteristics of microplastics and the type of polymers. The average abundance of microplastics in six river sediment samples was 802 items per kilogram of dry weight. The abundance in rivers was one to two orders of magnitude higher than in the tidal flat. White microplastic spheres were most commonly distributed in river sediments. Seven types of microplastics were identified, of which polypropylene was the most prevailing polymers presented. The study then conducted risk assessment of microplastics in sediments based on the observed results, and proposed a framework of environmental risk assessment. After reviewing waste disposal related legislation and regulations in China, this study conclude that in situ data and legitimate estimations should be incorporated as part of the practice when developing environmental policies aiming to tackle microplastic pollution.

In this study, 14 antibiotics and one metabolite were determined in sewages and size-dependent sewer sediments at three sampling sites in the city of Dresden, Germany. Adsorption and desorption experiments were conducted with fractionated sediments. All antibiotics and the metabolite investigated were determined in the sewages; 9 of 14 antibiotics and the metabolite were adsorbed to sewer sediments. The adsorbed antibiotic loads in ng of antibiotic per g of sediment correlated with antibiotic concentrations in ng of antibiotic per litre of sewage. The size fractions <63 μm, 63–100 μm and 100–200 μm had significantly higher loads of adsorbed antibiotics than bigger size fractions. In general, the adsorbed load decreased with an increasing size fraction, but size fractions >200 μm had similar levels of adsorbed antibiotic loads. An antibiotic-specific adsorption coefficient, normalized to organic content, was calculated: four antibiotics exceeded 10.0 L g⁻¹, three antibiotics fell below 1.0 L g⁻¹ and all residual antibiotics and the metabolite were in the range of 1.0–10.0 L g⁻¹. The adsorbed antibiotic load and the organic matter increased with time, generally. The mineral composition had a minor effect on the adsorption coefficients. Desorption dynamics of five antibiotics and the metabolite were quantified. Regardless of the size fraction, the predominant part of the equilibrium antibiotic concentration was desorbed after 10 min. The calculated desorption distribution coefficient indicated adsorption as irreversible at the pH investigated (7.5 ± 0.5).