Data on particulate matter of diameter <2.5 μm (PM2.5) in the city of Chongqing were first announced in 2013. We wished to assess the effects of pollutants on asthmatic children in Chongqing, China. Daily numbers of hospital visits because of asthma attacks in children aged 0–18 years in 2013 were collected from the Children's Hospital of Chongqing Medical University. Data on pollutants were accessed from the nine air quality-monitoring stations in Chongqing. A time-stratified case–crossover design was applied and conditional logistic regression was undertaken to analyze the data. We found that short-term exposure to PM10, PM2.5, sodium dioxide, nitrogen and carbon monoxide could trigger hospital visits for asthma in children. Nitrogen dioxide had an important role, whereas ozone had no effect.

The polycyclic aromatic hydrocarbons (PAHs) located on the epidermal tissues showed distinctive toxic effects to root, while the retention and distribution of PAHs on mangrove seedlings poorly understood. Our results confirmed that the partition coefficients (Kf) of the PAHs retained on the epidermal tissue of mangrove roots, such as Kandelia obovata, Avicennia marina and Aegiceras corniculatum, were much higher than the Poaceae plants roots, for example wheat and maize (Wild et al., 2005). Moreover, to the parent and alkyl PAHs, a well negative correlation was observed between the surface polarity of these three species of mangrove root and the Kf values (p < 0.05). To the N/O/S containing PAHs, these relationships were not obviously due to existing of the π-π, n-π interactions and hydrogen bonding between the N/O/S-containing PAHs and epidermal tissues. The PAHs retained on these three species of mangrove root epidermal tissues formed larger clusters than that of on Poaceae plants, such as wheat and maize (Wild et al., 2005) due to the limitation of the suberization of the root exodermis and endodermis. After exposure of 30 d, rhizo- and endophytic bacteria degraded parts of the N/O/S-containing PAHs to medium-lifetime fluorescence substances. To our knowledge, this is the first time to assess the retention of PAHs on the epidermal tissue of mangrove root, which will improve our understanding of the root uptake PAHs process.

Increased use of commercial titanium dioxide nanoparticles (TiO2 NPs) in consumer products most likely leads to their additional environmental release. Aggregation and disaggregation processes are expected to play an important role in the fate and transport of TiO2 NPs in natural aquatic ecosystems. Therefore, in this work, we have studied the colloidal stability of TiO2 NPs in the presence of extracellular polymeric substances (EPS) from Bacillus subtilis and the adsorption behavior of EPS on TiO2 NPs in aqueous solutions at different pH values and ionic strengths (IS). The adsorption and aggregation processes were found to depend on the solution chemistry. The mass fraction of EPS on TiO2 NPs decreased with increased pH and NaCl concentrations, which was verified by Fourier transform infrared spectroscopy. The presence of EPS can substantially influence the colloidal stability of TiO2 NPs. In deionized water, the aggregation of NPs was induced by the addition of EPS only when the pH was below the TiO2 NP point of zero charge (≈6). When the pH was equal to pHPZC, TiO2, the TiO2 NPs would rapidly form large aggregates, but the adsorption of EPS leads to partial fragmentation via electrostatic repulsion and steric hindrance. When the pH was greater than pHPZC, TiO2, the aggregation rate was minimally affected by the increased EPS concentration. In NaCl solution, the aggregation rate of TiO2 NPs obviously increased with increased NaCl concentration. The critical coagulation concentration (CCC) of TiO2 NPs is 13.9 mM in the absence of EPS and increases to 155.6, 213.7 and 316.4 mM in the presence of 1, 5 and 10 mg/L EPS in NaCl solution, respectively, which indicates that the steric hindrance occurs after the addition of EPS. This study suggests that environmental conditions and EPS concentration greatly modify the colloidal stability of TiO2 nanoparticles.

Increasing interests in carbon dots (CDs) research resulted in the increased production of CDs and the risk to be released into the environment, including surface water and groundwater. To assess the environmental behavior of CDs, the stability of CDs in aqueous solutions were first examined by different environmental conditions, followed by the systematic investigation of the adsorption behaviors of CDs onto Al2O3 surface. Electrostatic interactions were considered as the dominant forces in CDs adsorption onto Al2O3 process, which were further confirmed by controlling experiments as compared with other minerals or oxides, such as montmorillonite, kaolinite and SiO2. Theoretical calculations and characterization of Al2O3/CDs revealed chemisorptions exist in the adsorption process. Our investigation results provided fundamental understanding towards the interaction of CDs with Al2O3 surface, and potential fate of CDs under natural conditions in aquatic environment, as well as in soils and sediments.

Reactive nitrogen (Nr) is an important driver of global change, causing alterations in ecosystem biodiversity and functionality. Environmental assessments require monitoring the emission and deposition of both the amount and types of Nr. This is especially important in heterogeneous landscapes, as different land-cover types emit particular forms of Nr to the atmosphere, which can impact ecosystems distinctively. Such assessments require high spatial resolution maps that also integrate temporal variations, and can only be feasibly achieved by using ecological indicators. Our aim was to rank land-cover types according to the amount and form of emitted atmospheric Nr in a complex landscape with multiple sources of N. To do so, we measured and mapped nitrogen concentration and isotopic composition in lichen thalli, which we then related to land-cover data. Results suggested that, at the landscape scale, intensive agriculture and urban areas were the most important sources of Nr to the atmosphere. Additionally, the ocean greatly influences Nr in land, by providing air with low Nr concentration and a unique isotopic composition. These results have important consequences for managing air pollution at the regional level, as they provide critical information for modeling Nr emission and deposition across regional as well as continental scales.

Severe metal pollution due to industrial effluents releases has been documented in Jiulong River estuary, Southern China. However, integrated understanding of trace metal behavior in the sediment is lacking. In the present study, DGT (diffusive gradients in thin films) technique was employed together with sediment cores to study the porewater dynamics of trace metals as well as the benthic exchange fluxes from four sampling sites over three different months. The sedimentary environment showed distinct spatial and temporal variations due to effluent discharge and biological activities. Metal behavior was controlled by early diagenetic reactions below the interface, in suboxic layer and in deeper sediment. Precipitation as sulfides and adsorption onto Mn/Fe (hydr)oxides were important in scavenging trace metals. Estimated exchange fluxes at sediment-water interface in this estuary indicated that the overlying water was a major source for trace metals, whereas sediments could also be the source if surface remobilization (Mn/Fe reduction) dominated. Our results highlighted the impacts of both natural and anthropogenic processes on the source, fate and transformation of trace metals in this dynamic system.

Perturbations of rainwater chromophoric dissolved organic matter (CDOM) fluorescence induced by changes in rainfall intensity and pH were investigated by field observations and laboratory pH titrations. Microbial humic-like fluorophores dominated the rainwater CDOM pool, followed by tryptophan-like and tyrosine-like substances. Increased rainfall intensity had notable dilution effects on all six fluorescent components (C1-C6) identified using parallel factor (PARAFAC) analysis, the effect being especially pronounced for the microbial humic-like C1, tryptophan-like C3, and tyrosine-like C5. The results also indicated that increasing pH from 7 to 9 led to decreased fluorescence intensity (Fmax) of all the six components, while a pH increase from 5 to 7, resulted in increasing Fmax of terrestrial humic-like C2, tyrosine-like C5, and tryptophan-like C6 and decreasing microbial humic-like C1, tryptophan-like C3, and fulvic-like C4. Two-dimensional correlation spectroscopy (2D-COS) demonstrated that synchronous fluorescence responded first to pH modifications at fulvic-like wavelength (λEx/λEm = ∼316/416 nm), followed by tyrosine-like wavelength (λEx/λEm = ∼204/304 nm), tryptophan-like wavelength (λEx/λEm = ∼226/326 nm), microbial humic-like wavelength (∼295/395 nm), and finally terrestrial humic-like wavelength (∼360/460 nm). Our results suggest that a decrease in areas affected by acid rain in South China occurring at present may possibly result in apparent compositional changes of CDOM fluorescence. The decreased rainfall in South-West China and increased rainfall in North-West China during the past five decades may possibly accordingly result in increased and decreased Fmax of all the six components identified in South-West and North-West China, respectively.

Biochars have attracted tremendous attention due to their effects on soil improvement; they enhance carbon storage, soil fertility and quality, and contaminant (organic and heavy metal) immobilization and transformation. These effects could be achieved by modifying soil microbial habitats and (or) directly influencing microbial metabolisms, which together induce changes in microbial activity and microbial community structures. This review links microbial responses, including microbial activity, community structures and soil enzyme activities, with changes in soil properties caused by biochars. In particular, we summarized possible mechanisms that are involved in the effects that biochar-microbe interactions have on soil carbon sequestration and pollution remediation. Special attention has been paid to biochar effects on the formation and protection of soil aggregates, biochar adsorption of contaminants, biochar-mediated transformation of soil contaminants by microorganisms, and biochar-facilitated electron transfer between microbial cells and contaminants and soil organic matter. Certain reactive organic compounds and heavy metals in biochar may induce toxicity to soil microorganisms. Adsorption and hydrolysis of signaling molecules by biochar interrupts microbial interspecific communications, potentially altering soil microbial community structures. Further research is urged to verify the proposed mechanisms involved in biochar-microbiota interactions for soil remediation and improvement.

Metal tissue residue evaluation in benthic macroinvertebrates is an important component of an integrated approach to ecological risk assessment of metals and metalloids in the Nalón River basin (North Spain), where historic mining activities took place. The purpose of this study was to know the baseline tissue concentration of 7 metals (Cd, Cu, Cr, Hg, Ni, Pb, and Zn) and one metalloid (As) in aquatic oligochaetes, sediment burrower organisms, representative of the collector-gatherer functional feeding group in the macroinvertebrate community. Metal concentration was measured in sediment and field aquatic oligochaetes at several reference (minimally disturbed) sites of the Nalón River basin, selected following Water Framework Directive criteria. Metal tissue residues were measured separately in field microdriles and lumbricids and compared with tissue concentrations measured in the aquatic oligochaete Tubifex tubifex exposed to reference sediments from the Nalón and other Cantabrian River basins in 28-d chronic laboratory bioassays. Metal tissue residues in bioassay organisms attained usually higher levels than in field worms, in special for As, Cu, Hg and Zn, although metal levels were within the same order of magnitude. The baseline values for metals were calculated from 90th percentile (P90) values in field aquatic oligochaetes (microdriles and lumbricids). The P90 for Hg, As and Zn could efficiently discriminate Toxic and Non-Toxic sites, while baseline values calculated for the other metals deserve further research due either to the low range of values found in the present study, or to the regulation of the metal body concentration, as in the case of Cu.

Oil sands process-affected water (OSPW) — a byproduct of the oil sands industry in Northern Alberta, Canada – is currently stored in on-site tailings ponds. The goal of the present study was to investigate the interaction of OSPW with the olfactory system and olfactory-mediated behaviours of fish upon the first encounter with OSPW. The response of rainbow trout (Oncorhynchus mykiss) to different concentrations (0.1, 1, and 10%) of OSPW was studied using a choice maze and electro-olfactography (EOG), respectively. The results of the present study showed that rainbow trout are capable of detecting and avoiding OSPW at a concentration as low as 0.1%. Exposure to 1% OSPW impaired (i.e. reduced sensitivity) the olfactory response of rainbow trout to alarm and food cues within 5 min or less. The results of the present study demonstrated that fish could detect and avoid minute concentrations of OSPW. However, if fish were exposed to OSPW-contaminated water and unable to escape, their olfaction would be impaired.