In China, total Hg (HgT) and methylmercury (MeHg) were quantified in rice grain grown in three sites using water-saving rice cultivation methods, and in one Hg-contaminated site, where rice was grown under flooded conditions. Polished white rice concentrations of HgT (water-saving: 3.3±1.6ng/g; flooded: 110±9.2ng/g) and MeHg (water-saving 1.3±0.56ng/g; flooded: 12±2.4ng/g) were positively correlated with root-soil HgT and MeHg contents (HgT: r²=0.97, MeHg: r²=0.87, p<0.05 for both), which suggested a portion of Hg species in rice grain was derived from the soil, and translocation of Hg species from soil to rice grain was independent of irrigation practices and Hg levels, although other factors may be important. Concentrations of HgT and other trace elements were significantly higher in unmilled brown rice (p<0.05), while MeHg content was similar (p>0.20), indicating MeHg infiltrated the endosperm (i.e., white rice) more efficiently than inorganic Hg(II).

The soil-living springtail Folsomia candida is frequently used in reproduction bioassays to assess soil contamination. Alternatively, the response of genes to contamination is assessed. In this study the expression of F. candida’s gene encoding the deduced metallothionein-like motif containing protein (MTC) was assessed, using quantitative PCR, in response to six different metals, each at two concentrations in soil. The expression of mtc was induced after exposure to all metals, except for one chromium concentration. Exposure to soil originating from metal-contaminated field sites also induced mtc, while the expression did not change in response to a polycyclic aromatic hydrocarbon. Since this transcript is induced by most of the tested metals, it may potentially be a good indicator of metal contamination. The presented gene expression assay might become a useful tool to screen potentially polluted sites, in order to identify the ones that need further ecotoxicological investigation.

Observation and characterization of environmental pollution, focussing on Volatile Organic Compounds (VOCs), in a high-risk industrial area, are particularly important in order to provide indications on a safe level of exposure, indicate eventual priorities and advise on policy interventions. The aim of this study is to use the Solid Phase Micro Extraction (SPME) method to measure VOCs, directly coupled with atmospheric measurements taken on a small aircraft environmental platform, to evaluate and locate the presence of VOC emission sources in the Marghera industrial area. Lab analysis of collected SPME fibres and subsequent analysis of mass spectrum and chromatograms in Scan Mode allowed the detection of a wide range of VOCs. The combination of this information during the monitoring campaign allowed a model (Gaussian Plume) to be implemented that estimates the localization of emission sources on the ground.

The study presented the concentrations and distributions of polybrominated dibenzo-p-dioxins and polybrominated dibenzofurans (PBDD/Fs) as impurities in some commercial decabromodiphenyl ether (DBDE) mixtures that were produced by several manufacturers. The total concentrations of 12 2,3,7,8-substituted tetra- to octa-BDD/F congeners were found to be in the range of 3.4–13.6 (mean 7.8)μg/g, averagely accounting for 99% of total PBDD/Fs. OBDF was the prevailing congener, followed by 1,2,3,4,6,7,8-HpBDF. In addition, OBDD and 1,2,3,4,7,8-HxBDF were also obviously detectable. The total concentrations of PBDD/Fs varied both between the manufacturers and between the lots. On the basis of the global demand for the commercial DBDE in 2001, the annual potential emissions of PBDD/Fs were calculated coarsely to be 0.43 (range: 0.21–0.78)tons. The major dioxin congeners, OBDF and 1,2,3,4,6,7,8-HpBDF, presenting in DBDE, were estimated to be formed from BDE-209, BDE-206, and/or BDE-207 via an intra-molecular elimination of Br₂/HBr.

Polybrominated diphenyl ethers (PBDEs) are flame retardants that are commonly found in commercial and household products. These compounds are considered persistent organic pollutants. In this study, we used 4,4′-dibromodiphenyl ether (BDE-15) as a model compound to elucidate the sorption and desorption behavior of PBDEs in soils. The organic carbon-normalized sorption coefficient (KOC) of BDE-15 was more than three times higher for humin than for bulk soils. However, pronounced desorption hysteresis was obtained mainly for bulk soils. For humin, increasing concentration of sorbed BDE-15 resulted in decreased desorption. Our data illustrate that BDE-15 and probably other PBDEs exhibit high sorption affinity to soils. Moreover, sorption is irreversible and thus PBDEs can potentially accumulate in the topsoil layer. We also suggest that although humin is probably a major sorbent for PBDEs in soils, other humic materials are also responsible for their sequestration.

Using the monthly hydrogeochemical data of ChangLe River system from 2004 to 2008, total nitrogen (TN) export load (Sₙ) from nonpoint sources (NPS) to stream and in-stream attenuation load (AL) was estimated by the inverse and forward format of an existing in-stream nutrient transport equation, respectively. Estimated Sₙ contributed 96±2% of TN entering the river system, while AL reduced the input TN by 23±14% in average. In-stream TN attenuation efficiency in high flow periods (10±5% in average for the entire river system) was much lower than that in low flow periods (39±17%). TN attenuation efficiency in tributaries (28±16% in average) was much higher than that in mainstream (11±8%). Hydrological conditions are important in determining the spatio-temporal distributions of NPS TN export, stream attenuation and discharge. Increasing the water residence time might be a practical method for mitigating stream TN.

AsIII uptake in living cells is through aquaglyceroporin transporters, but it is unknown in arsenic-hyperaccumulator Pteris vittata. We investigated the effects of AsIII analogs glycerol and antimonite (SbIII) at 0–100 mM and aquaporin inhibitor AgNO₃ at 0–0.1 mM on the uptake of 0.1 mM AsIII or AsV by P. vittata over 1–2 h. Glycerol or SbIII didn’t impact AsIII or AsV uptake by P. vittata (p < 0.05), with As concentrations in the fronds and roots being 4.4–6.3 and 3.9–6.2 mg/kg. However, 0.01 mM AgNO₃ reduced As concentrations in the fronds and roots by 64% and 58%. Hence, AsIII uptake in P. vittata might be via an aquaporin transporter different from glycerol and SbIII transporters. Further as AsIII analogs and aquaporin inhibitor had no impact on AsV uptake, AsIII and AsV were likely taken up by different transporters in P. vittata. Our results imply a different AsIII transporter in P. vittata from other plants.

The biogeochemical dynamics of 15 perfluorinated compounds (PFCs) were investigated in a heavily urbanised river (River Seine, Paris, France). The target compounds included C4-C10 sulfonates and C5-C14 acids; eleven PFCs were detected and ∑PFCs ranged between 31 and 91 ng L⁻¹ (median: 47 ng L⁻¹). The molecular pattern was dominated by the perfluoroalkyl sulfonates PFHxS and PFOS (>54% of ∑PFCs), which were the only PFCs quantified in both the dissolved and particulate phases. For these PFCs, the sorbed fraction positively correlated with suspended sediment levels. Total PFC levels negatively correlated with river flow rate, which varied between 150 and 640 m³ s⁻¹. This suggests the predominance of point sources (likely WWTP effluent discharge), but a contribution of non-point sources such as combined sewer overflow could not be excluded. The annual PFC mass flow was estimated at 500 kg, which is less than observed for other large European rivers.

As part of a field campaign that studied the impact of Mexico City pollution plume at the local, sub-regional and regional levels, we studied transport-related changes in PM₁₀ composition, oxidative potential and in vitro toxicological patterns (hemolysis, DNA degradation). We collected PM₁₀ in Mexico City (T₀) and at a suburban-receptor site (T₁), pooled according to two observed ventilation patterns (T₀ → T₁ influence and non-influence). T₀ samples contained more Cu, Zn, and carbon whereas; T₁ samples contained more of Al, Si, P, S, and K (p < 0.05). Only SO₄ ⁻² increased in T₁ during the influence periods. Oxidative potential correlated with Cu/Zn content (r = 0.74; p < 0.05) but not with biological effects. T₁ PM₁₀ induced greater hemolysis and T₀ PM₁₀ induced greater DNA degradation. Influence/non-influence did not affect oxidative potential nor biological effects. Results indicate that ventilation patterns had little effect on intrinsic PM₁₀ composition and toxicological potential, which suggests a significant involvement of local sources.

Quantifying diffuse sources of pollution is becoming increasingly important when characterising river catchments in entirety – a prerequisite for environmental management. This study examines both low and high flow events, as well as spatial variability, in order to assess point and diffuse components of zinc pollution within the River West Allen catchment, which lies within the northern England lead–zinc Orefield. Zinc levels in the river are elevated under all flow regimes, and are of environmental concern. Diffuse components are of little importance at low flow, with point source mine water discharges dominating instream zinc concentration and load. During higher river flows 90% of the instream zinc load is attributed to diffuse sources, where inputs from resuspension of metal-rich sediments, and groundwater influx are likely to be more dominant. Remediating point mine water discharges should significantly improve water quality at lower flows, but contribution from diffuse sources will continue to elevate zinc flux at higher flows.