We assessed the potential of nitrate-nitrogen (NO₃-N) and fluoride (F) contamination in drinking groundwater of an intensively cultivated district in India as a function of its agricultural activities. Three hundred and forty two groundwater samples were collected from different types of wells with varying depths and analyzed for pH, EC, NO₃-N load and F content. Database on predominant cropping system, fertilizer and pesticide uses were also recorded for the district. The NO₃-N load in groundwater samples were low ranging from 0.01 to 5.97 mg L⁻¹ with only 6.7% of them contained greater than 3.0 mg L⁻¹. Samples from the habitational areas showed higher NO₃-N content over the agricultural fields. But all the samples contained NO₃-N below the 10 mg L⁻¹, the threshold limit fixed by WHO for drinking purpose. The content decreased with increasing depth of wells (r = -0.297, P <= 0.01) and increased with increasing rate of nitrogenous fertilizer application (r = 0.931, P <= 0.01) and was higher in areas where shallow-rather than deep-rooted crops are grown. Fluoride content in groundwater was also low (0.02 to 1.19 mg L⁻¹) with only 2.4% of them exceeding 1.0 mg L⁻¹ posing a potential threat of fluorosis in some locality. On average, its content varied little spatially and along depth of sampling aquifers indicating homogeneity in lithology of the district. The content showed a significant positive correlation (r = 0.237, P <= 0.01) with the amount of phosphatic fertilizer (single super phosphate) used for agriculture. Results thus indicated that the groundwater of the study area is presently safe for drinking purpose but some anthropogenic activities associated with intensive cultivation had a positive influence on its loading with NO₃-N and F.

Atmospheric mercury deposition by wet and dry processes contributes mercury to terrestrial and aquatic systems. Factors influencing the amount of mercury deposited to boreal forests were identified in this study. Throughfall and open canopy precipitation samples were collected in 2005 and 2006 using passive precipitation collectors from pristine sites located across the Superior National Forest in northern Minnesota, USA. Samples were collected approximately every 2 weeks and analyzed for total (THg) and methyl mercury (MeHg). Forest canopy type and density were the primary influences on THg and MeHg deposition. Highest THg and MeHg concentrations were measured beneath conifer canopies (THg mean = 19.02 ng L⁻¹; MeHg mean = 0.28 ng L⁻¹) followed by deciduous throughfall (THg mean = 12.53 ng L⁻¹; MeHg mean = 0.19 ng L⁻¹) then open precipitation (THg mean = 8.19 ng L⁻¹; MeHg mean = 0.12 ng L⁻¹). The greater efficiency of conifers at scavenging THg and MeHg from the atmosphere may increase the risk of mercury related water quality issues in conifer-dominated systems.

Two soils with explosives and metals were evaluated for the degradation efficiency of explosives by native microorganisms under anaerobic conditions. The commercially available method Daramend®, amended with zero-valent iron (ZVI), was compared with a horse-manure-amended compost and a treatment with ZVI alone. In a moderately contaminated soil, Daramend® and ZVI treatment gave significantly higher removal rates compared to compost and control treatments (Tukey's test, P < 0.05). The largest overall decrease in ecotoxicity, measured with bioluminescent bacteria (Vibrio fischeri), was achieved with ZVI treatment. In a more contaminated soil, no degradation of contaminants and no decline in soil toxicity could be distinguished after the same time period. Problems with establishment of anaerobic conditions during parts of the remediation process and low microbial activity due to acute toxicity of contaminants are plausible explanations. Redistribution that could potentially lead to mobilization of the co-contaminant Pb was not observed in either of the soils during the biological treatments.

The fate and transport of tricyclazole and imidacloprid in paddy plots after nursery-box application was monitored. Water and surface soil samples were collected over a period of 35 days. Rates of dissipation from paddy waters and soils were also measured. Dissipation of the two pesticides from paddy water can be described by first-order kinetics. In the soil, only the dissipation of imidacloprid fitted to the simple first-order kinetics, whereas tricyclazole concentrations fluctuated until the end of the monitoring period. Mean half-life (DT₅₀) values for tricyclazole were 11.8 and 305 days, respectively, in paddy water and surface soil. The corresponding values of imidacloprid were 2.0 and 12.5 days, respectively, in water and in surface soil. Less than 0.9% of tricyclazole and 0.1% of imidacloprid were lost through runoff during the monitoring period even under 6.3 cm of rainfall. The pesticide formulation seemed to affect the environmental fate of these pesticides when these results were compared to those of other studies.

Effects of elevated arsenic (As) concentrations on hydroponic Kalmi (Ipomoea aquatica L.) were investigated. Plants were treated with 0, 10, 25, and 50 μM As in the greenhouse for 14 days. Arsenic was added from sodium meta-arsenite (NaAsO₂). Visible toxicity symptom could not easily be recognized without visible growth reduction. Little brown spots on the leaf blade were found at 50 μM As treatment. Dry matter yields decreased by 18.8%, 43.2%, and 78.2% in leaves; 23.6%, 56.4%, and 81.8% in stems; and 11.0%, 28.6%, and 63.7% in roots in the 10-, 25-, and 50-μM As treatments, respectively. Arsenic concentrations increased in leaves (except in 50 μM As treatment), stems, and roots with increasing As concentrations in the medium. Roots contained 12.7, 11.3, and 10.5 times higher As concentrations as compared to stems and 15.5, 15.9, and 52.8 times higher as compared to leaves in the 10-, 25-, and 50-μM As treatments, respectively. Arsenic concentration followed the trend of roots > stems > leaves. Kalmi concentrated unaccepted levels of As in leaf and stem tissues for human consumption in the As-treated plants. Based on 10% dry weight (DW) reduction, the critical toxicity level (CTL) of As in the leaves was 7.02 and 23.6 μg g⁻¹ DW in stems.

This laboratory-scale study investigated initially the potential of heavy metal removal from a metal-finishing wastewater using fly and bottom ash from a power plant as coagulants. It was found that the maximum heavy metal content in the ash-sludge mix was obtained at a fly ash-to-bottom ash ratio of 1.5:1 and a stirring time of 3 h, which resulted in heavy metal removal (i.e., Cr, Ni, Cu, Zn, Cd, and Pb) in excess of 99%, with effluent concentrations below the corresponding regulatory standards of Thailand. Furthermore, the feasibility of using fly ash as an admixture to stabilize and solidify the ash-sludge mix generated previously was explored. Results indicated that the stabilization/solidification process can achieve a high level of heavy metal removal efficiency from the ash-sludge mix. The optimum ratio regarding chromium leaching was found to be 1:0.75:0.75 (cement:fly ash:ash-sludge). In addition, the compressive strength and the chromium leaching concentration of the solidified sludge were within acceptable levels for secure landfill disposal and/or use as a construction material.

Water and sediment were studied to assess the impact of wastes from an area used for a disposal area of treated petrochemical effluents in Rio Grande do Sul, Brazil. The study was performed using the Daphnia magna (Straus 1820) for chronical evaluations, mutagenesis in Salmonella/microsome assays, and micronuclei induction in cultures of V79 cell to assess genotoxicity. Six sites were defined for chronic and genotoxic tests by micronuclei induction with liquid and sediment samples. Long-term tests were planned in semi-static flow, with microcrustaceans 2 to 26 h old in the beginning of assays. The minimum level of reproduction required to maintain the species was not reached. There are delays for the beginning of the reproductive process. Survival was also affected in some samples. The reproductive responses were more sensitive on identifying environmental quality than the survival rate. The study of mutagenicity by Salmonella/microsome assay made it possible to define the seasonality of the components showing greater frequency in winter. The predominant event was the frameshift mutation in assays with the presence of metabolism. However, the cytotoxic activity, although present in all seasons, was less frequent in winter. The genotoxicity analysis in V79 cells exposed to liquid samples from the area also showed that cytotoxicity was the most frequent event. This may have interfered in the detection of a potential micronuclei induction. The results showed that, even after treatment, effluents disposed on the soil continue with active pollutants interfering in cladoceran's quality of life, cellular physiology, and DNA integrity.

The dynamic removal of cadmium from aqueous solutions by natural and surfactant-modified Mexican zeolitic rocks (clinoptilolite-heulandite type) in fixed bed column systems was investigated. The performances of fixed bed columns were described through the breakthrough curves obtained from column experiments and the values of column parameters predicted as a function of bed height. The column adsorption data were evaluated in terms of the bed adsorption capacity and the efficiency of the process. The experimental results fitted well the bed depth service time model (BDST) for both adsorbents, and the empty bed residence time model (EBRT) was used to optimize column operating conditions. The surface modification of the zeolitic rock with surfactant affected the removal of cadmium in fixed bed systems. Moreover, a column experiment with surfactant modified zeolitic rock previously saturated with 4-chlorophenol was carried out and the results showed that this saturation had a negative effect on the performance of the column.

We tested the hypothesis that there would be measurable losses of phosphorus (P) from surficial sediments of Upper Klamath Lake (UKL), Oregon, if sediments were a source of P during an algal bloom. We compared concentrations of total and forms of P at various depths in cores collected before and after the onset of a large Aphanizomenon flos-aquae bloom. Concentrations of inorganic P were determined in extraction solutions of MgCl₂ (1 M, pH 8), citrate-dithionite-bicarbonate, and 1 M HCl. Sediments below 2 cm were dominated by residual P which is defined as total P minus inorganic P. During the study period, data from the top 2-cm of sediment indicated (a) significant decrease in total P concentration, primarily associated with iron oxyhydroxides at one site, and (b) significant increase in total P concentration associated with residual P at a second site. Data from two other sites indicated no net changes in concentrations of total P.

The objective of this investigation is to analyse the variations of xenobiotic concentrations and the fluxes of dissolved xenobiotics during runoff events in the small rural Mess catchment (35 km²) in the Southwestern part of Luxembourg. Sulfonamides, tetracyclines, analgesics and hormones, dissolved nutrients, sulphate and chloride were measured to gather information about runoff generation. Typically, the highest values can be found during the first flush mainly in the rising limb of the flood hydrographs. The highest concentrations in eleven flood events are measured for ibuprofen (2,383 ng l⁻¹), estrone (27 ng l⁻¹) and diclofenac (20 ng l⁻¹). From the tetracycline group tetracycline (9 ng l⁻¹) itself is of relevance, while the sulfonamides are mainly represented by sulfamethoxazole (5 ng l⁻¹). The variable patterns of chemographs are attributed to the heterogeneous runoff generation characterised by different reactions of storm overflows from the combined sewer systems. During single flood events, the fluxes of ibuprofen (maximum 24,000 mg), 17α-ethinylestradiol (122 mg), 17β-estradiol (32 mg) or estrone (274 mg) are rather low.