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.

Intensive human activities, in particular agricultural and industrial production have led to heavy metal accumulation in the peri-urban agricultural soils of China threatening soil environmental quality and agricultural product security. A combination of spatial analysis (SA), Pb isotope ratio analysis (IRA), input fluxes analysis (IFA), and positive matrix factorization (PMF) model was successfully used to assess the status and sources of heavy metals in typical peri-urban agricultural soils from a rapidly developing region of China. Mean concentrations of Cd, As, Hg, Pb, Cu, Zn and Cr in surface soils (0–20 cm) were 0.31, 11.2, 0.08, 35.6, 44.8, 119.0 and 97.0 mg kg−1, respectively, exceeding the local background levels except for Hg. Spatial distribution of heavy metals revealed that agricultural activities have significant influence on heavy metal accumulation in the surface soils. Isotope ratio analysis suggested that fertilization along with atmospheric deposition were the major sources of heavy metal accumulation in the soils. Based on the PMF model, the relative contribution rates of the heavy metals due to fertilizer application, atmospheric deposition, industrial emission, and soil parent materials were 30.8%, 33.0%, 25.4% and 10.8%, respectively, demonstrating that anthropogenic activities had significantly higher contribution than natural sources. This study provides a reliable and robust approach for heavy metals source apportionment in this particular peri-urban area with a clear potential for future application in other regions.

Ionizing radiation causes a variety of effects, including DNA damage associated to cancers. However, the effects in progeny from irradiated parents is not well documented. Using zebrafish as a model, we previously found that parental exposure to ionizing radiation is associated with effects in offspring, such as increased hatching rates, deformities, increased DNA damage and reactive oxygen species. Here, we assessed short (one month) and long term effects (one year) on gene expression in embryonic offspring (5.5 h post fertilization) from zebrafish exposed during gametogenesis to gamma radiation (8.7 or 53 mGy/h for 27 days, total dose 5.2 or 31 Gy) using mRNA sequencing. One month after exposure, a global change in gene expression was observed in offspring from the 53 mGy/h group, followed by embryonic death at late gastrula, whereas offspring from the 8.7 mGy/h group was unaffected. Interestingly, one year after exposure newly derived embryos from the 8.7 mGy/h group exhibited 2390 (67.7% downregulated) differentially expressed genes. Overlaps in differentially expressed genes and enriched biological pathways were evident between the 53 mGy/h group one month and 8.7 mGy/h one year after exposure, but were oppositely regulated. Pathways could be linked to effects in adults and offspring, such as DNA damage (via Atm signaling) and reproduction (via Gnrh signaling). Comparison with gene expression analysis in directly exposed embryos indicate transferrin a and cytochrome P450 2x6 as possible biomarkers for radiation response in zebrafish. Our results indicate latent effects following ionizing radiation exposure from the lower dose in parents that can be transmitted to offspring and warrants monitoring effects over subsequent generations.

The estimation of PM₂.₅-related mortality is becoming increasingly important. The accuracy of results is largely dependent on the selection of methods for PM₂.₅ exposure assessment and Concentration-Response (C-R) function. In this study, PM₂.₅ observed data from the China National Environmental Monitoring Center, satellite-derived estimation, widely collected geographic and socioeconomic information variables were applied to develop a national satellite-based Land Use Regression model and evaluate PM₂.₅ exposure concentrations within 2013–2015 with the resolution of 1 km × 1 km. Population weighted concentration declined from 72.52 μg/m³ in 2013 to 57.18 μg/m³ in 2015. C-R function is another important section of health effect assessment, but most previous studies used the Integrated Exposure Regression (IER) function which may currently underestimate the excess relative risk of exceeding the exposure range in China. A new Shape Constrained Health Impact Function (SCHIF) method, which was developed from a national cohort of 189,793 Chinese men, was adopted to estimate the PM₂.₅-related premature deaths in China. Results showed that 2.19 million (2013), 1.94 million (2014), 1.65 million (2015) premature deaths were attributed to PM₂.₅ long-term exposure, different from previous understanding around 1.1–1.7 million. The top three provinces of the highest premature deaths were Henan, Shandong, Sichuan, while the least ones were Tibet, Hainan, Qinghai. The proportions of premature deaths caused by specific diseases were 53.2% for stroke, 20.5% for ischemic heart disease, 16.8% for chronic obstructive pulmonary disease and 9.5% for lung cancer. IER function was also used to calculate PM₂.₅-related premature deaths with the same exposed level used in SCHIF method, and the comparison of results indicated that IER had made a much lower estimation with less annual amounts around 0.15–0.5 million premature deaths within 2013–2015.

Chemical compositions of streambed biofilms from a major river of central Japan (the Kushida River) were obtained, with data of associated sediments (fine-grained fractions < 63 μm) and dissolved components of waters, in order to provide preliminary information about biogeochemical significance of streambed biofilms. During the sampling period (July 31st to August 3rd, 2013), dissolved components of the river waters were influenced by the dam reservoir. Concentrations of NO₃⁻, silica (as Si), SO₄²⁻, PO₄³⁻ and Ca²⁺ decreased across the dam, whereas Fe and Mn increased across the dam, and then decreased downstream rapidly. Streambed biofilms contain significant amount of non-nutrient elements such as Al (up to 21% as Al₂O₃ on water and others-free basis), indicating that they are contaminated as siliciclatic (silt and clay) materials. Siliciclastic materials in the biofilms are basically compositionally similar to fine-grained (<63 μm) fractions of streambed sediments. However, some elements such as Ca, P, Mn, and Zn are markedly enriched in the biofilms. Particularly, Mn concentrations in the biofilm samples collected just below the dam reservoir are very high (∼4.0 wt %), probably due to accumulation from the discharged water. Concentrations of trace elements such as P, Cr, Cu, Zn and V appear to be controlled by amounts of Fe-oxides and/or Mn-oxides in biofilms. Numbers of factors are involved in controlling chemical compositions of streambed biofilms, including amount of contaminated siliciclastics, authigenic mineral formation, adsorption of dissolved materials and microbial metabolisms. As demonstrated by this study, systematic analyses including major elements and comparison with associated sediments and waters could reveal biogeochemistry of this complex system.

The Sanjiang Plain, which is located in northeastern China, given the distribution of temperate freshwater wetlands there and this region has considerable significance in ensuring food security in China. Two periods of farmland reclamation that occurred during the last 100 years led to the loss of nearly 80% of the area of the native wetlands, and the development of agriculture has also increased the potential environmental risks to the residual wetlands. To evaluate the effects of farmland reclamation on the accumulation of key elements within the residual wetland ecosystems, six wetland profiles in the Sanjiang Plain are selected in this study. Using age-depth models and the concentrations of key elements, the historical accumulation rates (ARs) of carbon (C), nutrient elements (N and P) and potentially toxic elements (Hg, As, Pb, Cu, and Zn) over the last 150 years are reconstructed. The results show that the ARs of the potentially toxic elements in two of the wetland profiles begin to increase during the first reclamation period (AD 1900–1930). The ARs of both of the key elements clearly increase in all of the wetland profiles during the second reclamation period (AD 1950–1980). After land reclamation had ceased, increases in population and the development of industry became major factors that caused the potential environmental risks to wetlands to continue to increase from AD 1980 to the present. During the last 100 years, reclamation has increased the potential environmental risks and has led to the storage of additional carbon in the residual wetlands of the Sanjiang Plain.

Global water safety is facing great challenges due to increased population and demand. There is an urgent need to develop suitable water treatment strategy for small rural and remote communities in low-income developing countries. In order to find a low-cost solution, the reduction of E. coli using ceramic water disk coated with nano ZnO was investigated in this study. The performance of modified ceramic disk filters was influenced by several factors in the filter production process. Based on the factorial analysis, the pore size of the disk filters was the most significant factor for influencing E. coli removal efficiency and the clay content was the most significant one for influencing flow rate of modified disk filters. The coating of nano ZnO led to the change of disk filter surface and porosity. The reduction of E. coli could be attributed to both filter retention and photocatalytic antibacterial activity of nano ZnO. The effects of filter operation factors including initial E. coli concentration, illumination time and lamp power on E. coli removal effectiveness were also revealed. The results can help find a safe and cost-effective approach to solve drinking water problems in small rural and remote communities of developing regions.

The cyanobacterium Cylindrospermopsis raciborskii is of particular concern due to its ability to fix nitrogen (N), sporadic bloom, potential toxicity and apparent invasiveness. However, the toxicity associated behavior and response of toxic C. raciborskii under N fluctuations in water have been poorly investigated. The present study initiated based on the field survey in which Cylindrospermopsis species was found to have a high fitness under nitrate concentrations fluctuating from 0.02 mg L−1 to 2.90 mg L−1 in Chinese freshwater lakes. Examination on the role of short-term N fluctuations was conducted in two C. raciborskii strains which were exposed to a range of N concentrations supplied in two patterns, namely one-time pattern and ten-time pattern in which the equal amount of N was divided into ten-time accretions. The results showed the growth of both strains were not vulnerable to the transient nutrient fluctuations. The toxic strain showed considerable toxicological flexibility with the highest yield of cylindrospermopsin (CYN) obtained in the absence of N and the lowest in full medium. Generally, larger amounts of total CYN were observed at lower N levels, indicating that N deficiency promoted the intracellular accumulation and simultaneously restrained the extracellular release of CYN. Furthermore, CYN production was significantly different in two N supply patterns. The maximum quotas of intracellular and extracellular CYN in one-time pattern were respectively 2.79–3.53 and 3.94–7.20 times higher compared to the ten-time pattern. To our knowledge, our results are the first evidence of toxicity variations of C. raciborskii to the impermanent N fluctuations, shedding new light on its toxicological plasticity.

Microplastic polystyrene foam has been found widely in the environment and is readily transported by wind or water. Beached and virgin foams of size 0.45–1 mm were prepared as sorbents to study oxytetracycline sorption. Enhanced adsorption were found in the beached foams compared to the virgin foams, corresponding to the higher specific surface area, micropore area and the degree of oxidation of the former. The Freundlich Kf value was 894 ± 84 ((mg kg⁻¹) (mg L⁻¹)¹/ⁿ) for oxytetracycline adsorption on the beached foams, approximately twice as high as on the virgin foams. Effects of solution pH on adsorption to the beached foams were more pronounced to the virgin foams. Maximum adsorption occurred at pH 5 at which electrostatic repulsion between the microplastic surface and the oxytetracycline zwitterion was minimal, indicating that electrostatic interaction may have regulated adsorption. Moreover, H-bonding and multivalent cationic bridging mechanisms may also have affected the adsorption of oxytetracycline to the beached foams as reflected by the ionic effects. Adsorption was promoted more in the presence of humic acid than of fulvic acid, perhaps owing to π-π conjugation between the humic acid and the microplastic surface which led to enhanced electrostatic attraction for oxytetracycline. This study suggests that weathered polystyrene foams may act as carriers of antibiotics in the environment and their potential risks to ecosystem and human health merit further investigation.