Foliar δ³⁴S values of three soil-growing plant species (Platanus Orientalis L., Osmanthus fragrans L. and Cinnamomum camphora) have been analyzed to indicate atmospheric sulfur. The foliar δ³⁴S values of the three plant species averaged −3.11±1.94‰, similar to those of both soil sulfur (−3.73±1.04‰) and rainwater sulfate (−3.07±2.74‰). This may indicate that little isotopic fractionation had taken place in the process of sulfur uptake by root or leaves. The δ³⁴S values changed little in the transition from mature leaves to old/senescing leaves for both the plane tree and the osmanthus tree, suggestive of little isotope effect during sulfur redistribution in plant tissues. Significantly linear correlation between δ³⁴S values of leaves and rainwater sulfate for the plane and osmanthus trees allowed the tracing of temporal variations of atmospheric sulfur by means of foliar sulfur isotope, while foliage δ³⁴S values of the camphor is not an effective indicator of atmospheric sulfur.

The role of indigenous and non-indigenous arbuscular mycorrhizal fungi (AMF) on As uptake by Plantago lanceolata L. growing on substrate originating from mine waste rich in As was assessed in a pot experiment. P. lanceolata inoculated with AMF had higher shoot and root biomass and lower concentrations of As in roots than the non-inoculated plants. There were significant differences in As concentration and uptake between different AMF isolates. Inoculation with the indigenous isolate resulted in increased transfer of As from roots to shoots; AMF from non-polluted area apparently restricted plants from absorbing As to the tissue; and plants inoculated with an AMF isolate from Zn–Pb waste showed strong As retainment within the roots. Staining with dithizone indicated that AMF might be actively involved in As accumulation. The mycorrhizal colonization affected also the concentration of Cd and Zn in roots and Pb concentration, both in shoots and roots.

Cities can be modelled as giant organisms, with their own metabolic processes, and can therefore be studied using the same tools used for biological metabolic systems. The complicated distribution of compartments within these systems and the functional relationships among them define the system's network structure. Taking Beijing as an example, we divided the city's internal system into metabolic compartments, then used ecological network analysis to calculate a comprehensive utility matrix for the flows between compartments within Beijing's metabolic system from 1998 to 2007 and to identify the corresponding functional relationships among the system's compartments. Our results show how ecological network analysis, utility analysis, and relationship analysis can be used to discover the implied ecological relationships within a metabolic system, thereby providing insights into the system's internal metabolic processes. Such analyses provide scientific support for urban ecological management.

The fate of the ¹⁴C-labeled herbicides ethidimuron (ETD), methabenzthiazuron (MBT), and the fungicide anilazine (ANI) in soils was evaluated after long-term aging (9–17 years) in field based lysimeters subject to crop rotation. Analysis of residual ¹⁴C activity in the soils revealed 19% (ETD soil; 0–10 cm depth), 35% (MBT soil; 0–30), and 43% (ANI soil; 0–30) of the total initially applied. Accelerated solvent extraction yielded 90% (ETD soil), 26% (MBT soil), and 41% (ANI soil) of residual pesticide ¹⁴C activity in the samples. LC-MS/MS analysis revealed the parent compounds ETD and MBT, accounting for 3% and 2% of applied active ingredient in the soil layer, as well as dihydroxy-anilazine as the primary ANI metabolite. The results for ETD and MBT were matching with values obtained from samples of a 12 year old field plot experiment. The data demonstrate the long-term persistence of these pesticides in soils based on outdoor trials.

Three common disinfectants were selected in this study to investigate their toxicity to Daphnia magna. The methods used in this study included the traditional acute toxicity test, new embryo toxicity test, and teratogenic test. The study concluded that the acute toxicity of the three disinfectants to young daphnids and embryos were hypochlorite > formaldehyde > m-cresol. The effects on growth mostly occurred in the late stages of organogenesis. Of the organs, the Malpighian tube was the most sensitive to disinfectants during embryonic organogenesis. After exposure of the disinfectants to sunlight for 4 h, acute toxicity and teratogenic effects of hypochlorite on young daphnids decreased by 30% and 71%, respectively, while those of formaldehyde decreased by 35% and 49%, respectively. In addition, comparing toxic endpoints of the three disinfectants with and without sunlight exposure, the embryo tests were equally sensitive to the three-week reproduction test in this study.

The Laurentian Great Lakes region of North America contains substantial aquatic resources and mercury-contaminated landscapes, fish, and wildlife. This special issue emanated from a bi-national synthesis of data from monitoring programs and case studies of mercury in the region, here defined as including the Great Lakes, the eight U.S. states bordering the Great Lakes, the province of Ontario, and Lake Champlain. We provide a retrospective overview of the regional mercury problem and summarize new findings from the synthesis papers and case studies that follow. Papers in this issue examine the chronology of mercury accumulation in lakes, the importance of wet and dry atmospheric deposition and evasion to regional mercury budgets, the influence of land–water linkages on mercury contamination of surface waters, the bioaccumulation of methylmercury in aquatic foods webs; and ecological and health risks associated with methylmercury in a regionally important prey fish.

Data from 104 sediment cores from the Great Lakes and “inland lakes” in the region were compiled to assess historical and recent changes in mercury (Hg) deposition. The lower Great Lakes showed sharp increases in Hg loading c. 1850–1950 from point-source water dischargers, with marked decreases during the past half century associated with effluent controls and decreases in the industrial use of Hg. In contrast, Lake Superior and inland lakes exhibited a pattern of Hg loading consistent with an atmospheric source – gradual increases followed by recent (post-1980) decreases. Variation in sedimentary Hg flux among inland lakes was primarily attributed to the ratio of watershed area:lake area, and secondarily to a lake’s proximity to emission sources. A consistent region-wide decrease (∼20%) of sediment-Hg flux suggests that controls on local and regional atmospheric Hg emissions have been effective in decreasing the supply of Hg to Lake Superior and inland lakes.

The antiviral agent oseltamivir acid (OA, the active metabolite of Tamiflu®) may occur at high concentrations in wastewater during pandemic influenza events. To eliminate OA and its antiviral activity from wastewater, ozonation and advanced oxidation processes were investigated. For circumneutral pH, kinetic measurements yielded second-order rate constants of 1.7 ± 0.1 × 10⁵ and 4.7 ± 0.2 × 10⁹ M⁻¹ s⁻¹ for the reaction of OA with ozone and hydroxyl radical, respectively. During the degradation of OA by both oxidants, the antiviral activity of the treated aqueous solutions was measured by inhibition of neuraminidase activity of two different viral strains. A transient, moderate (two-fold) increase in antiviral activity was observed in solutions treated up to a level of 50% OA transformation, while for higher degrees of transformation the activity corresponded to that caused exclusively by OA. OA was efficiently removed by ozonation in a wastewater treatment plant effluent, suggesting that ozonation can be applied to remove OA from wastewater.

Environment Canada recently developed a clean method suitable for sampling trace levels of metals in surface waters. The results of sampling for total mercury in the Laurentian Great Lakes between 2003 and 2009 give a unique basin-wide perspective of concentrations of this important contaminant and represent improved knowledge of mercury in the region. Results indicate that concentrations of total mercury in the offshore regions of the lakes were within a relatively narrow range from about 0.3 to 0.8 ng/L. The highest concentrations were observed in the western basin of Lake Erie and concentrations then declined towards the east. Compared to the offshore, higher levels were observed at some nearshore locations, particularly in lakes Erie and Ontario. The longer-term temporal record of mercury in Niagara River suspended sediments indicates an approximate 30% decrease in equivalent water concentrations since 1986.

The HERMES model-predicted Hg concentrations and fluxes in Lake Ontario were based on twelve lake and drainage basin variables (i.e., water temperature, precipitation rate, air Hg, surface area, mean depth, water volume, water inflow rate, inflow water Hg, inflow and lake suspended particulate matter, air–water and water–air mass transfer coefficients, and sedimentation rate). The HERMES model-predicted Hg water and surface sediment concentrations were found to be significantly correlated (±20%) with measured values (r² = 0.94, p < 0.0001, n = 13) and mechanistic model predictions (LOTOX2-Hg, r² = 0.95, p < 0.0001, n = 10). The predictive capacity of HERMES was previously tested on smaller (≤1 km²) lakes in Nova Scotia and Ontario, Canada (i.e., water and sediment Hg concentrations were ±15% of measured data). Results suggest that HERMES could be applicable to a broad range of lake sizes. Uncertainty analyses on HERMES model input variables indicated a larger atmospheric Hg contribution for Lake Ontario when compared to previous predictions for smaller lakes.