Given its wide distribution in the natural environment and global transport potential, mercury (Hg) is regarded as a ubiquitous pollutant. In this study, we carried out nation-wide sampling campaigns across China to investigate the distribution of Hg in agricultural soils. Concentrations of Hg in the soils collected in 2011 and 2016 ranged from 0.04 to 0.69 and 0.06–0.78 mg kg−1, respectively. Based on the data from 2016, the reserve of Hg in the surface arable soils (0–20 cm) in China was 4.1 × 104 metric tons and Chinese cultivated soils accounted for 63.4–364 metric tons of Hg released to the global atmosphere. The soil Hg concentrations were significantly higher than the reference background level, highlighting the impacts of anthropogenic activities. The vertical distribution pattern showed a clear enrichment at the surface and a decrease with depth of the soils. Comparison of calculated geo-accumulation indexes among individual provinces showed that Northwest China had higher levels of Hg contamination than other regions of China, likely due to long-term energy related combustions in the area. Soil Hg level showed strong positive correlations with organic matter contents of soil, as well as the mean annual precipitation and temperature of the sampling locations. The non-carcinogenic human health risks of soil Hg were below the threshold level, but the general risk to the ecosystem was considerable. The increases in Hg accumulation from 2011 to 2016 at provincial level were found to relate to coal combustion, power generation and per capita GDP. This examination of energy consumption and socioeconomic drivers for China's soil Hg reserve increase is critical for direct Hg control by guiding policy-making and targets of technology development in era of rapid economic growth.

Satellite-based aerosol optical depth (AOD) is now comprehensively applied to estimate ground-level concentrations of fine particulate matter (PM2.5). This study aimed to construct the AOD-PM2.5 estimation models over Taiwan. The AOD-PM2.5 modeling in Taiwan island is challenging owing to heterogeneous land use, complex topography, and humid tropical to subtropical climate conditions with frequent cloud cover and prolonged rainy season. The AOD retrievals from the MODerate resolution Imaging Spectroradiometer (MODIS) onboard the Terra and Aqua satellites were combined with the meteorological variables from reanalysis data and high resolution localized land use variables to estimate PM2.5 over Taiwan island from 2005 to 2015. Ten-fold cross validation was carried out and the residuals of the estimation model at various locations and seasons are assessed. The cross validation (CV) R2 based on monitoring stations were 0.66 and 0.66, with CV root mean square errors of 14.0 μg/m3 (34%) and 12.9 μg/m3 (33%), respectively, for models based on Terra and Aqua AOD. The results provided PM2.5 estimations at locations without surface stations. The estimation revealed PM2.5 concentration hotspots in the central and southern part of the western plain areas, particularly in winter and spring. The annual average of estimated PM2.5 concentrations over Taiwan consistently declined during 2005–2015. The AOD-PM2.5 model is a reliable and validated method for estimating PM2.5 concentrations at locations without monitoring stations in Taiwan, which is crucial for epidemiological study and for the assessment of air quality control policy.

The wide use of antibiotics in aquaculture for prophylactic and therapeutic purposes can potentially lead to the prevalence of antibiotic resistance genes (ARGs). This study reports for the first time the profile of ARGs from effluents of coastal aquaculture located in South Jeolla province and Jeju Island, South Korea. Using quantitative PCR (qPCR), twenty-two ARGs encoding tetracycline resistance (tetA, tetB, tetD, tetE, tetG, tetH, tetM, tetQ, tetX, tetZ, tetBP), sulfonamide resistance (sul1, sul2), quinolone resistance (qnrD, qnrS, aac(6′)-Ib-cr), β-lactams resistance (blaTEM, blaCTX, blaSHV), macrolide resistance (ermC), florfenicol resistance (floR) and multidrug resistance (oqxA) and a class 1 integrons-integrase gene (intI1) were quantified. In addition, Illumina Miseq sequencing was applied to investigate microbial community differences across fish farm effluents. Results from qPCR showed that the total number of detected ARGs ranged from 4.24 × 10⁻³ to 1.46 × 10⁻² copies/16S rRNA gene. Among them, tetB and tetD were predominant, accounting for 74.8%–98.0% of the total ARGs. Furthermore, intI1 gene showed positive correlation with tetB, tetD, tetE, tetH, tetX, tetZ tetQ and sul1. Microbial community analysis revealed potential host bacteria for ARGs and intI1. Two genera, Vibrio and Marinomonas belonging to Gammaproteobacteria, showed significant correlation with tetB and tetD, the most dominant ARGs in all samples. Also, operational taxonomic units (OTUs)-based network analysis revealed that ten OTUs, classified into the phyla Proteobacteria, Cyanobacteria/Chloroplast, Bacteroidetes, Verrucomicrobia and an unclassified phylum, were potential hosts of tetracycline resistance genes (i.e., tetA, tetG, tetH, tetM, tetQ and tetZ). Further systematic monitoring of ARGs is warranted for risk assessment and management of antibacterial resistance from fish farm effluents.

Global change affects the functioning of forest ecosystems and the services they provide, but little is known about the interactive effects of co-occurring global change drivers on important functions such as tree growth and vitality. In the present study we quantified the interactive (i.e. synergistic or antagonistic) effects of atmospheric nitrogen (N) deposition and climatic variables (temperature, precipitation) on tree growth (in terms of tree-ring width, TRW), taking forest ecosystems with European beech (Fagus sylvatica L.) as an example. We hypothesised that (i) N deposition and climatic variables can evoke non-additive responses of the radial increment of beech trees, and (ii) N loads have the potential to strengthen the trees' sensitivity to climate change. In young stands, we found a synergistic positive effect of N deposition and annual mean temperature on TRW, possibly linked to the alleviation of an N shortage in young stands. In mature stands, however, high N deposition significantly increased the trees’ sensitivity to increasing annual mean temperatures (antagonistic effect on TRW), possibly due to increased fine root dieback, decreasing mycorrhizal colonization or shifts in biomass allocation patterns (aboveground vs. belowground). Accordingly, N deposition and climatic variables caused both synergistic and antagonistic effects on the radial increment of beech trees, depending on tree age and stand characteristics. Hence, the nature of interactions could mediate the long-term effects of global change drivers (including N deposition) on forest carbon sequestration. In conclusion, our findings illustrate that interaction processes between climatic variables and N deposition are complex and have the potential to impair growth and performance of European beech. This in turn emphasises the importance of multiple-factor studies to foster an integrated understanding and models aiming at improved projections of tree growth responses to co-occurring drivers of global change.

Laboratory research has indicated that antibiotics had negative effects on coral growth by disturbing natural microbiota; however, no field studies have reported antibiotic contamination levels and their influence on coral growth in natural coral reef regions (CRRs). This study investigated antibiotic occurrence and sources in the surface water from CRRs that have suffered from rapid coral degradation and evaluated their risk to coral growth. These regions are in the South China Sea, including four coastal and two offshore CRRs. The results show that 13 antibiotics were detected in the coastal CRRs with concentrations ranging from 10⁻²–10⁰ ng L⁻¹, while 5 antibiotics occurred in offshore CRRs (300–950 km from the mainland), with concentrations ranging from 10⁻² to 10⁻¹ ng L⁻¹. Their concentrations decreased gradually from the coast to offshore in the transport process. However, Yongxing Island, which is approximately 300 km from the mainland, was an exception with relatively higher concentrations than the surrounding reefs because of the ever-increasing human activity on the island. The presence of anthropogenic contaminants antibiotics in CRRs may be a potential risk to coral growth.

Pharmaceutically active compounds (PhACs) are excreted by humans and animals and released into the aquatic environment through wastewater, which can have potential negative impacts on ecological systems. To conduct a nationwide investigation of the occurrence of PhACs in water resources in China, an analytical procedure based on solid-phase extraction (SPE) and LC-MS/MS was used to measure 45 PhACs in surface water samples from a network of 29 rivers across 31 provinces in China in 2014 and 2015. PhACs were prevalent in all sampled streams. The concentrations of commonly detected PhACs were comparable to those detected in other countries. High total concentrations (mean > 1 μg L−1) of all tested PhACs were primarily detected in areas under extreme water stress, specifically northern and eastern coastal areas. Source apportionment based on the profiles of the target compounds found that 54% of the PhACs in China originated from freshly discharged untreated sewage. Metformin (MET) and its biodegradation product, guanylurea (GUL), were used as a pair of indicators to predict PhAC contamination levels and differentiate between biotreated and unbiotreated wastewater. High MET/GUL can be used to indicate untreated wastewater, whereas low MET/GUL values are a strong indicator of treated wastewater. Furthermore, wastewater biotreatment ratios were calculated. We estimated that the biotreatment ratios of most of the provinces in China were less than 50%. We conclude that more attention should be paid to untreated sewage water, especially water in rural areas rather than the existing concentration on urban sewage treatment-oriented management.

Municipal solid wastes (MSW) can be composted to become an organic fertilizer. However, besides plant nutrients, it can also contain high concentration of some toxic metals than can pollute agricultural soils, contaminate food, animals and human being. A greenhouse experiment was carried out for two purposes: i) to evaluate the concentrations of cadmium, copper, chromium, nickel, lead and zinc in four Brazilian MSW composts, and, ii) to know which is the best solution for extracting those metals in phytoavailable form from the composts. In order to evaluate the phytoavailability of metals, they were extracted with six chemical extractants: i) water, ii) 0.05 mol L⁻¹ Ca(NO₃)₂, iii) 0.1 mol L⁻¹ HCl, iv) 0.005 mol L⁻¹ DTPA at pH 7.3, v) 0.05 mol L⁻¹ CaCl₂ and vi) Mehlich 3 solution. In addition, lettuces were cultivated as a test plant in pots containing 1.8 kg of MSW compost as substrate. Fifty-six days later, lettuce plants were harvested. New lettuces were then planted for a second cycle, and then harvested after fifty-six days. Semi-total concentration of metals in composts and total in plants was also determined through an extraction with nitric-perchloric acid. Semi–total concentration of Cd and Pb exceeded the intervention limits from Brazil in the four studied composts, and lettuce plants were polluted by those two elements. Therefore, compost made of MSW must be characterized before being used for agricultural soils. Copper and nickel in phytoavailable were effectively extracted with the strongest chelating agents used, HCl and Mehlich 3, probably because most metal is bound to organic matter in the compost. Cadmium, chromium, lead and zinc were no efficiently extracted with any of the tested extractants.

Phthalates are widely used as plasticizers that influence sexual and reproductive development. Here, we investigated whether di-(2-ethylhexyl) phthalate (DEHP) affects macrophage polarization that are associated with tumor initiation and progression. No changes were observed in LPS- or ConA-stimulated in vitro spleen B or T cell proliferation for 48 h, respectively. In contrast, macrophage functions were inhibited in response to DEHP for 12 h as judged by LPS-induced H₂O₂ and NO production and zymosan A-mediated phagocytosis. When six weeks old male mice were pre-exposed to 4.0 mg/kg DEHP for 21 days before the injection of B16F10 melanoma cells and post-exposed to 4.0 mg/kg DEHP for 7 days, tumor nodule formation and the changes in tumor volume were higher than those in control group. Furthermore, when male mice were intraperitoneally pretreated with DEHP for 3 or 4 weeks and peritoneal exudate cells (PECs) or bone marrow-derived macrophages (BMDMs) were incubated with lipopolysaccharide (LPS), the expression of COX-2, TNF-α, and IL-6 was reduced in DEHP-pretreated cells as compared with that in LPS-stimulated control cells. While the production of nitric oxide (NO) for 18 h was reduced by LPS-stimulated PECs and M1-type BMDMs, IL-4 expression was enhanced in LPS-stimulated BMDMs. When BMDMs were incubated with IL-4 for 30 h, arginase 1 for M2-type macrophages was increased in transcriptional and translational level. Data implicate that macrophages were differentially polarized by DEHP treatment, which reduced M1-polarzation but enhanced M2-polarization. Taken together, these data demonstrate that DEHP could affect in vivo immune responses of macrophages, leading to the suppression of their tumor-preventing ability. This suggests that individuals at high risk for tumor incidence should avoid long-term exposure to various kind of phthalate including DEHP.

Even though the Amazon region is widely studied, there is still a gap regarding Cr exposure and its risk to human health. The objectives of this study were to 1) determine Cr concentrations in seven chemical fractions and 6 particle sizes in Amazon soils, 2) quantify hexavalent Cr (CrVI) concentrations using an alkaline extraction, 3) determine the oral and lung bioaccessible Cr, and 4) assess Cr exposure risks based on total and bioaccessible Cr in soils. The total Cr in both A (0–20 cm) and B (80–100 cm) horizons was high at 2346 and 1864 mg kg⁻¹. However, sequential extraction indicated that available Cr fraction was low compared to total Cr, with Cr in the residual fraction being the highest (74–76%). There was little difference in total Cr concentrations among particle sizes. Hexavalent Cr concentration was also low, averaging 0.72 and 2.05 mg kg⁻¹ in A and B horizon. In addition, both gastrointestinal (21–22 mg kg⁻¹) and lung (0.95–1.25 mg kg⁻¹) bioaccessible Cr were low (<1.2%). The low bioavailability of soil Cr and its uniform distribution in different particle sizes indicated that Cr was probably of geogenic origin. Exposure based on total Cr resulted in daily intake > the oral reference dose for children, but not when using CrVI or bioaccessible Cr. The data indicated that it is important to consider both Cr speciation and bioaccessibility when evaluating risk from Cr in Amazon soils.

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.