Biochar has potential for application for in situ metal-contaminated sediment remediation, mainly because of its cost-effectiveness. In this study, the effectiveness of Phyllostachys pubescens (PP) biochar for immobilization of cadmium (Cd) chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) by decreasing the bioavailable fraction was investigated using a series of laboratory sediment remediation microcosms. The results demonstrated that biochar could significantly reduce the bioavailable fraction of metals (except for Cr) by diffusive gradients in thin film (DGT) measurement in porewater. Additionally, amended sediment treated with 15% w/w biochar resulted in 79.71%, 73.20%, 54.86%, 49.75%, 31.16% and 0.99% reductions in the acid-soluble fraction for Cu, Pb, Ni, Zn, Cd, and Cr, respectively. Similarly, bioaccumulation of metals (except for Cr) by Limnodrilus hoffmeisteri was reduced by 18.45%–59.15% in biochar amended sediment. PP biochar at 15% could also reduce the inhibition or lethality rate by 37.5%, 18.1% and 36.3% for Chlorella vulgaris, Daphnia magna and luminescent bacteria Vibrio qinghaiensis, respectively. Overall, these results demonstrate the potential for biochar application for in situ sediment remediation.

High abundances of antibiotic-resistant pathogenic bacteria (ARPB) and antibiotic resistance genes (ARGs) in agricultural soil-plant systems have become serious threats to human health and environmental safety. Therefore, it is crucial to develop targeted technology to control existing antibiotic resistance (AR) contamination and potential dissemination in soil-plant systems. In this work, polyvalent bacteriophage (phage) therapy and biochar amendment were applied separately and in combination to stimulate ARPB/ARG dissipation in a soil-lettuce system. With combined application of biochar and polyvalent phage, the abundance of Escherichia coli K-12 (tetR) and Pseudomonas aeruginosa PAO1 (ampR + fosR) and their corresponding ARGs (tetM, tetQ, tetW, ampC, and fosA) significantly decreased in the soil after 63 days' incubation (p < 0.05). Similar results for endophytic K-12 and PAO1, and ARGs, were also obtained in lettuce tissues following combined treatment. Additionally, high throughput sequencing revealed that biochar and polyvalent phage synergetically improved the structural diversity and functional stability of the indigenous bacterial communities in soil and the endophytic ones in lettuce. Hence, this work proposes a novel biotechnology that combines biochar amendment and polyvalent phage therapy to achieve targeted inactivation of ARPB, which stimulates ARG dissipation in soil-lettuce systems.

Narragansett Bay is a temperate estuary on the Atlantic coast of Rhode Island in the north-eastern United States, which receives organic pollutants from urban and industrial activities in its watershed, though detailed knowledge on sources and fluxes is missing. Twenty-four polyethylene passive samplers were deployed in the surface water of the watershed around Narragansett Bay during June–July of 2014, to examine the spatial variability and possible sources of priority pollutants, namely dissolved polycyclic aromatic hydrocarbons (PAHs) and polybrominated diphenyl ethers (PBDEs). Dissolved ∑22PAH concentrations ranged from 3.6 to 340 ng L−1, and from 2.9 to 220 pg L−1 for ∑12PBDE. The spatial variability of the concentrations was correlated to land use pattern and population distribution, in particular with human activities within 2 km of sampling sites. River discharges derived from the concentrations of PAHs and PBDEs measured here were 10–20 times greater than their previously measured concentrations in the open waters of Narragansett Bay. These results imply that river waters are the main source of PAHs and PDBEs to the Bay and that major sink terms (e.g., sedimentation, degradation) affect their concentrations in the estuary. Predicted PAH and PBDE toxicity based on dissolved concentrations did not exceed 1 toxic unit, suggested that no toxicity occurred at the sampling sites.

Nitrous oxide (N2O) is a potent greenhouse gas that contributes to climate change and stratospheric ozone destruction. Nitrogen-enriched rivers are significant sources of atmospheric N2O. This study conducted a one-year field campaign in seven N-enriched rivers draining urban, rural, and agricultural land to determine the link between the production, concentrations, and emissions of N2O and land use. Estimated N2O fluxes varied between 1.30 and 1164.38 μg N2O-N m−2 h−1 with a mean value of 154.90 μg N2O-N m−2 h−1, indicating that rivers were the net sources of atmospheric N2O. Concentrations of N2O ranged between 0.23 and 29.21 μg N2O-N L−1 with an overall mean value of 3.81 μg N2O-N L−1. Concentrations of ammonium and nitrate in urban and rural rivers were high in the cold season. The concentrations were also high in agricultural rivers in the wet season. N2O concentrations and emissions in rural and urban rivers followed a similar pattern to ammonium and a similar pattern to nitrate in agricultural rivers. A strong link between the concentrations and emissions of N2O and land use was observed. N2O concentrations in and emissions from the rivers draining the urban and rural areas were significantly higher than the rivers draining the agricultural areas (P < 0.01). Stepwise regression analysis indicated that dissolved N2O were primarily influenced by NH4+ in agricultural rivers and by NO3− in rural rivers; while dissolved N2O in urban rivers was primarily predicted by temperature and reflected the integrated impact of sewage input and river hydrology. Nitrate-N and NO3--O isotope data and linear regression of N2O and river water variables strongly indicated that dissolved N2O was mainly derived from nitrification in agricultural rivers and denitrification in rural and urban rivers.

In recent years, photochemical smog and gray haze-fog have frequently appeared over northern China. To determine the spatial distribution of volatile organic compounds (VOC) during a pollution period, tethered balloon flights were conducted over a suburban site on the North China Plain. Statistical analysis showed that the VOCs concentrations peaked at the surface, and decreased with altitude. A rapid decrease appeared from the surface to 400 m, with concnetrations of alkanes, alkenes, aromatics and halocarbons decreasing by 48.0%, 53.3%, 43.3% and 51.1%, respectively. At heights in the range of 500–1000 m, alkenes concnetrations decline by 40.2%; alkanes and halocarbons concnetrations only decreased by 24.8% and 6.4%, respectively; and aromatics increased slightly by 5.5%. High concentrations VOCs covered a higher range of height (400 m) on heavy pollution days due to lacking of diffusion power. The VOCs concentrations decreased by 50% at 200 m on light pollution days. The transport of air mass affected the composition and concentration of high-altitude VOCs, especially on lightly polluted days. These air masses originated in areas with abundant traffic and combustion sources. Reactive aromatics (kOH>20,000 ppm−1 min−1 and kOH<20,000 ppm−1 min−1) were the main contributor to the ozone formation, accounting for 37%, on the surface on light pollution days. The contribution increased to 52% with pollution aggravated, and increased to 64% with height. The contributions of reactive aromatics were influenced by the degree of air mass aging. Under the umbrella of aging air mass, the contribution of reactive aromatics increased with height.

Currently the land use and land use change (LULUC) emits 1.3 ± 0.5 Pg carbon (C) year⁻¹, equivalent to 8% of the global annual emissions. The objectives of this study were to quantify (1) the impact of LULUC on greenhouse gas (GHG) emissions in a subtropical region and (2) the role of conservation agriculture to mitigate GHG emissions promoting ecosystem services. We developed a detailed IPCC Tier 2 GHG inventory for the Campos Gerais region of southern Brazil that has large cropland area under long-term conservation agriculture with high crop yields. The inventory accounted for historical and current emissions from fossil fuel combustion, LULUC and other minor sources. We used Century model to simulate the adoption of conservation best management practices, to all croplands in the region from 2017 to 2117. Our results showed historical (1930–2017) GHG emissions of 412 Tg C, in which LULUC contributes 91% (376 ± 130 Tg C), the uncertainties ranged between 13 and 36%. Between 1930 and 1985 LULUC was a major source of GHG emission, however from 1985 to 2015 fossil fuel combustion became the primary source of GHG emission. Forestry sequestered 52 ± 24 Tg C in 0.6 Mha in a period of 47 years (1.8 Tg C Mha⁻¹ year⁻¹) and no-till sequestered 30.4 ± 24 Tg C in 2 Mha in a period of 32 years (0.5 Tg C Mha⁻¹ year⁻¹) being the principal GHG mitigating activities in the study area. The model predictions showed that best management practices have the potential to mitigate 13 years of regional emissions (330 Tg C in 100 years) or 105 years of agriculture, forestry and livestock emissions (40 Tg C in 100 years) making the agriculture sector a net carbon (C) sink and promoting ecosystem services.

The sorption and desorption behaviour of samarium (Sm), an emerging contaminant, was examined in soil samples at varying Sm concentrations. The obtained sorption and desorption parameters revealed that soil possessed a high Sm retention capacity (sorption was higher than 99% and desorption lower than 2%) at low Sm concentrations, whereas at high Sm concentrations, the sorption-desorption behaviour varied among the soil samples tested. The fractionation of the Sm sorbed in soils, obtained by sequential extractions, allowed to suggest the soil properties (pH and organic matter solubility) and phases (organic matter, carbonates and clay minerals) governing the Sm-soil interaction. The sorption models constructed in the present work along with the sorption behaviour of Sm explained in terms of soil main characteristics will allow properly assessing the Sm-soil interaction depending on the contamination scenario under study. Moreover, the sorption and desorption Kd values of radiosamarium in soils were strongly correlated with those of stable Sm at low concentrations (r = 0.98); indicating that the mobility of Sm radioisotopes and, thus, the risk of radioactive Sm contamination can be predicted using data from low concentrations of stable Sm.

An ecosystem in a cold climate river basin is vulnerable to the effects of climate change affecting permafrost thaw and glacier retreat. We currently lack sufficient data and information if and how hydrological processes such as glacier retreat, snowmelt and freezing-thawing affect sediment and nutrient runoff and transport, as well as N₂O emissions in cold climate river basins. As such, we have implemented well-established, semi-empirical equations of nitrification and denitrification within the Soil and Water Assessment Tool (SWAT), which correlate the emissions with water, sediment and nutrients. We have tested this implementation to simulate emission dynamics at three sites on the Canadian prairies. We then regionalized the optimized parameters to a SWAT model of the Athabasca River Basin (ARB), Canada, calibrated and validated for streamflow, sediment and water quality. In the base period (1990–2005), agricultural areas (2662 gN/ha/yr) constituted emission hot-spots. The spring season in agricultural areas and summer season in forest areas, constituted emission hot-moments. We found that warmer conditions (+13% to +106%) would have a greater influence on emissions than wetter conditions (−19% to +13%), and that the combined effect of wetter and warmer conditions would be more offsetting than synergetic. Our results imply that the spatiotemporal variability of N₂O emissions will depend strongly on soil water changes caused by permafrost thaw. Early snow freshet leads to spatial variability of soil erosion and nutrient runoff, as well as increases of emissions in winter and decreases in spring. Our simulations suggest crop residue management may reduce emissions by 34%, but with the mixed results reported in the literature and the soil and hydrology problems associated with stover removal more research is necessary. This modelling tool can be used to refine bottom-up emission estimations at river basin scale, test plausible management scenarios, and assess climate change impacts including climate feedback.

Antibiotic resistant bacteria are a threat to human life. Recently, sewers have been identified as potential reservoirs. The intermittent injection of sewage into adjacent surface waters is inevitable, due to capacity limitations of the urban drainage system. Information regarding the effect to natural freshwater biofilms (NFB) due to the intermittent contaminations are scarce. Therefore, a fundamental screening is necessary. In April, we placed NFB-attachment constructions in a brook upstream and downstream from urban drainage overflow constructions. In meanwhile two sampling campaigns were conducted. The sewage and the brook water were collected to gather information about antibiotic background exposure of ciprofloxacin (CIP), clarithromycin (CLA) and doxycycline (DOX). Six months later we experimentally determined the oxygen uptake rate (OUR) of the NFB-communities after a 24 h lasting exposure with additionally dosed antibiotics. Concentrations of 0.1, 1.0 and 10.0 mg L⁻¹ were selected. CIP, CLA and DOX were individually dosed, and also in mixtures. The mean antibiotic background concentration in sewage was in a range of 575.5–1289.1 ng L⁻¹, which mainly exceeded the concentrations published in literature. The determined mean concentration in the brook was in a range of 4.6–539.0 ng L⁻¹. The first significant inhibition of the OUR with individually dosed antibiotics started mainly at a concentration of 1.0 mg L⁻¹. Antibiotics in a mixture with concentrations of 0.1 and 1.0 mg L⁻¹ were as effective as single dosed antibiotics with a concentration of 10.0 mg L⁻¹. The increased antibiotic tolerance and resistance of NFB-communities downstream of the combined sewer overflow (CSO) structure was a consequence of a severe impact due to urban drainage overflows. Hence, NFB-communities downstream of CSO-constructions are hot spots of antibiotic tolerant and resistant subpopulations and access restrictions should be announced, if an infection risk is present.

Bisphenol A (BPA) is an endocrine-disrupting chemical. Studies have shown that the exposure to BPA is associated with attention-deficit/hyperactivity disorder (ADHD) during adolescent development. However the direct clinical evidence is limited. To investigate the possible association between environmental BPA exposure and the altered behavior of children, a case-control study was conducted with children aged 6–12 years in Guangzhou, China. Two hundred fifteen children diagnosed with ADHD and 253 healthy children from Guangzhou were recruited as the case and control groups, respectively. Urinary BPA and 8-hydroxy-2′-deoxyguanosine (8-OHdG, a biomarker of oxidative DNA damage) concentrations were determined by high-performance liquid chromatography/tandem spectrometry. The results showed that concentrations of urinary BPA for the case group were significantly higher than those for the control group (3.44 vs 1.70 μg/L; 4.63 vs 1.71 μg/g Crt. p < .001). A stepwise increase in the odds ratios for ADHD was observed with the increasing quartiles of children's urinary BPA (first quartile: reference category; second quartile adjusted OR: 1.79, 95% CI: 0.95–3.37; third quartile adjusted OR: 7.44, 95% CI: 3.91–14.1; fourth quartile adjusted OR: 9.41, 95% CI: 4.91–18.1). When the BPA levels were stratified by gender, the odds of ADHD among boys and girls increased significantly with urinary BPA concentrations (adjusted OR: 4.58, 95% CI: 2.84–7.37; adjusted OR: 2.83, 95% CI: 1.17–6.84). Urinary 8-OHdG concentrations in the ADHD children were significantly higher than those in the control group. Furthermore, the linear regression analysis results indicated that a significant relationship existed between BPA exposure and 8-OHdG levels (R = 0.257, p < .001). Our findings provide direct evidence that childhood BPA exposure may be related to ADHD and 8-OHdG concentrations for children. Moreover, BPA exposure could increase the higher occurrence of ADHD for boy than for girls.