The speciation of mercury (Hg) in Minamata Bay (Japan) was studied over a 2-year period (2006–2008). Concentrations of dissolved total Hg, dissolved methylmercury (MeHg), particulate total Hg, and suspended solids were 0.43 ± 0.14 ng/l (mean ± standard deviation), 0.10 ± 0.06 ng/l, 3.04 ± 2.96 ng/l, and 5.94 ± 2.10 mg/l, respectively. Correlations between concentrations of particulate total Hg and suspended solids at four depths (surface: 0 m; mid-depth: −6 m, −10 m; and bottom +1 m layer) were only significant in the bottom +1 m layer. The mean dissolved MeHg concentration and the ratio of dissolved MeHg to dissolved total Hg were considerably higher in summer compared to other seasons. The data suggest that bottom sediment was not the sole source of MeHg, and that MeHg may be produced in the water column by the conversion of divalent Hg eluted from resuspended bottom sediment. The correlation between seawater characteristics such as salinity, temperature, dissolved oxygen (DO), and dissolved MeHg concentration indicates that Hg methylation could be influenced by the heterotrophic activity of microorganisms in the seawater. In particular, inverse correlations were observed between DO, salinity, and MeHg concentration. However, dissolved MeHg concentrations did not correlate with seawater characteristics such as pH or chlorophyll-a.

Photolysis, sonolysis, and photosonolysis of common groundwater contaminants, namely 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene, were investigated using a flow-through photosono reactor system. Simulated groundwater containing the chlorinated volatile organic compounds (VOCs) was exposed to ultraviolet light (UV), ultrasonication (US), and UV and US concurrently (UVUS), without a photo catalyst. VOC removal efficiencies of the UV, US, and UVUS treatment processes were computed from the VOC concentrations in influent and effluent of the reactor. The process using UVUS exhibited larger degradation efficiencies than that with UV and US separately in most cases; however, statistical analysis showed that the UVUS treatment efficiency is likely to be additive of the UV and US treatment efficiencies. The results also showed that the increase of the detention time from 26 to 60 min had no significant effect on the VOC removal efficiencies in these processes.

Fungicides are used to prevent foliar diseases on a wide range of vegetable, field, fruit, and ornamental crops. They are generally more effective as protective rather than curative treatments, and hence tend to be applied before infections take place. Less than 1% of US soybeans were treated with a fungicide in 2002 but by 2006, 4% were treated. Like other pesticides, fungicides can move-off of fields after application and subsequently contaminate surface water, groundwater, and associated sediments. Due to the constant pressure from fungal diseases such as the recent Asian soybean rust outbreak, and the always-present desire to increase crop yields, there is the potential for a significant increase in the amount of fungicides used on US farms. Increased fungicide use could lead to increased environmental concentrations of these compounds. This study documents the occurrence of fungicides in select US streams soon after the first documentation of soybean rust in the US and prior to the corresponding increase in fungicide use to treat this problem. Water samples were collected from 29 streams in 13 states in 2005 and/or 2006, and analyzed for 12 target fungicides. Nine of the 12 fungicides were detected in at least one stream sample and at least one fungicide was detected in 20 of 29 streams. At least one fungicide was detected in 56% of the 103 samples, as many as five fungicides were detected in an individual sample, and mixtures of fungicides were common. Azoxystrobin was detected most frequently (45% of 103 samples) followed by metalaxyl (27%), propiconazole (17%), myclobutanil (9%), and tebuconazole (6%). Fungicide detections ranged from 0.002 to 1.15 μg/L. There was indication of a seasonal pattern to fungicide occurrence, with detections more common and concentrations higher in late summer and early fall than in spring. At a few sites, fungicides were detected in all samples collected suggesting the potential for season-long occurrence in some streams. Fungicide occurrence appears to be related to fungicide use in the associated drainage basins; however, current use information is generally lacking and more detailed occurrence data are needed to accurately quantify such a relation. Maximum concentrations of fungicides were typically one or more orders of magnitude less than current toxicity estimates for freshwater aquatic organisms or humans; however, gaps in current toxicological understandings of the effects of fungicides in the environment limit these interpretations.

This study was conducted to determine the potential of in situ biodegradation and identify the geochemical and microbial processes of the petroleum-contaminated subsurface environment using integrated hydro-bio-geochemical markers so that the risk of contamination to subsurface environment can be better understood. The contamination process and corresponding bio-geo-chemistry were analysed in parallel with geochemical and multi-variant statistical modelling at a petroleum-contaminated site in the northeast China. The total petroleum hydrocarbon analysed in the monitoring wells and soil profile demonstrated heavy contamination with potential risk to human health and eco-environment. Further detailed analysis of petroleum fractions revealed a clear spatial variation of organic compositions in groundwater. It was evident that biodegradation and preferential biodegradability contributed considerably to the fraction distribution pattern, which can also be implicated by carbon and microbial respiration in the subsurface environment. The steady decrease in SO4 2- concentration, detection of S2-, and increase in pH and alkalinity (HCO3 -) in groundwater during the monitoring period demonstrated that sulphate reduction was the dominant biodegradation process in most contaminated zones. The results of statistical analysis further suggested that the hydro-geochemical environment was mainly controlled by the regional hydro-geochemical and sulphate reduction process associated closely with the total petroleum hydrocarbon. Knowledge from the comprehensive study provides useful insight on fate, transport and risk assessment of the petroleum contaminants in the shallow subsurface environment.

This study evaluated the copper ion adsorption capacity of sugarcane bagasse in natura and chemically modified with citric acid and sodium hydroxide. Adsorption analyses in batch system were carried out in function of contact time with the adsorbent and adsorbate concentration. Flame atomic absorption spectrometry was used to determine the copper concentrations. Adsorption experimental data were fitted to Langmuir and Freundlich linear models, and the maximum adsorption capacity was estimated for copper ions in function of modifications. The chemical modifications were confirmed at 1,730 cm−1 peak in infrared spectra, referring to the carboxylate groups. The required time for the adsorption to reach equilibrium was 24 h and the kinetics follows the behavior described by the pseudo-second order equation. Besides, a significant improvement of the copper adsorption has been observed after the bagasse treatment, where the maximum adsorption capacity was 31.53 mg g−1 for copper using modified bagasse with nitric acid according to Langmuir isotherm linear model. The high uptake of copper ions from aqueous medium verified by chemically modified sugarcane bagasse makes this material an attractive alternative for effluent treatment and avoids environmental contamination.

Streptomyces sp. MC1, previously isolated from sugar cane, has shown ability to reduce Cr(VI) in liquid minimal medium and soil samples. The objective of this work was to demonstrate the intracellular chromium accumulation by Streptomyces sp. MC1 under different culture conditions. This strain was able to accumulate up to 3.54 mg of Cr(III) per gram of wet biomass, reducing the 98% of Cr(VI) and removing 13.9% of chromium from the culture medium supernatants. Streptomyces sp. MC1 chromium bioaccumulation ability was corroborated by using Timm's reagent technique, a low-cost method, which has been used by first time to detect chromium deposits in bacteria. The results of atomic absorption spectrometry, scanning electron microscopy, and energy dispersive X-ray analysis suggest that the mechanism of Cr(VI) resistance observed in Streptomyces sp. MC1 includes adsorption coupled with reduction to Cr(III), and finally, Cr(III) bioaccumulation. This mechanism have special relevance to remediation of Cr(VI) contaminated environments by Streptomyces sp. MC1.

The influence of a change from daily to weekly sampling of bulk precipitation on the obtained deposition values was studied with parallel sampling for 8 months at the station of Virolahti in 2004. Due to dry deposition, the deposition values of the whole period were found to be 5–70% higher from weekly sampling than from daily sampling, the biggest difference being for K+, Ca2+, Mg+ and Na+. The collection efficiencies of the summer sampler and the winter sampler compared to the standard rain gauge were studied from daily sampling in 1991–2003 and weekly sampling in 2004–2008. The performance was best in summer and in winter with rain samples (median value 85–88%), while the median value for daily snow samples was 72%. In winter, the total sum of precipitation collected in the daily sampler and the weekly sampler was 78% and 69%, respectively. The deficit in the weekly sampler in winter was concluded to be due to evaporation, while from the summer sampler no evaporation seemed to occur. Use of the precipitation amount measured by the standard rain gauge when calculating annual precipitation-weighted mean values gave higher mean concentrations than the use of the precipitation measured by the deposition sampler itself, the biggest difference of 8–11% being in the sea-salt ions Cl−, Mg+ and Na+. It was concluded that the concentration and deposition values measured by daily and weekly bulk sampling are incompatible, and should not be combined into the same time series.

Coal is one of the major sources of fuel for electricity production and will continue to be used for many more decades. Thus, it is important to study the effects of disposal of coal burning byproducts including fly ash into the environment. In this study, the solubility of cations and anions from the fly ash in water is discussed. Also, the fractionation of different metals from fly ash in water is studied to understand which fraction of the metals would likely be mobilized. The results from these studies suggested that the metals in the fly ash are bound mostly to carbonate, organic, and residual fractions. Also, when water solubility data are modeled with a geochemical model (Visual MINTEQ), the saturation index predictions suggested that brucite (Mg(OH)2) and calcite (CaCO3) could potentially precipitate and mineralize the atmospheric CO2. Such mineralization process could potentially reduce the leaching of toxic metals from fly ash. Results from this study will be helpful in understanding the fate of different metals from fly ash land disposal environments.

The objective of this study is to develop a method for using the single-well natural gradient drift test (SWNGDT) in the field to assess in situ aerobic cometabolism of trichloroethylene (TCE) and to analyze microbial community changes. The SWNGDT was performed in a monitoring well installed in a TCE-contaminated aquifer in Wonju, South Korea. The natural gradient drift biostimulation test (NGDBT) and surrogate test (NGDST) were performed by injecting dissolved solutes (bromide (a tracer), toluene (a growth substrate), ethylene (a nontoxic surrogate substrate to probe for TCE transformation activity), dissolved oxygen (DO, an electron acceptor), and nitrate (nutrient)) into the aquifer. Push–pull blocking tests (PPBT) were also performed to examine whether the monooxygenase of toluene oxidizers is involved in the degradation of toluene and the transformation of ethylene. Through the NGDBT, NGDST, and PPBT, we confirmed that the addition of toluene and oxygen in these field tests stimulated indigenous toluene utilizers to cometabolize aerobically TCE, with the following results: (1) the observed simultaneous utilization of toluene and DO; (2) the transformation of ethylene to ethylene oxide and propylene to propylene oxide; and (3) the transformation of TCE. Furthermore, the results of restriction fragment length polymorphism suggested that the microbial community shifts and the microbes capable of transforming TCE are stimulated by injecting the growth substrate, toluene.

The sequential elution technique (SET) is used to determine the distribution of elements in the different cell fractions of mosses. The extracellular extractants most commonly used in this technique are NiCl2 and EDTA, although there are certain disadvantages associated with their use. In order to avoid such problems, we searched for new extractants that displace extracellularly bound metals, either because they are present at high concentrations (Ca) or because they have a high affinity for cation exchange sites (Hg and Au). The compounds HCl, NaCl, and CaCl2 were tested as extractants of the former type, as possible alternatives for the determination of extracellular metals in the moss Pseudoscleropodium purum. Calcium chloride was finally chosen as is it potentially the most successful in terms of binding to the cation exchange sites without altering the membrane permeability. The concentration chosen was 160 mM, as this yielded maximum displacement of Zn without membrane alterations. An experiment was then carried out to test the efficiency of Ca in extracting extracellular Zn, under laboratory and field conditions. In addition, Hg and Au were tested, at different concentrations, as extractants with high affinity for cation exchange sites, as neither of these elements has previously been used in the SET, and both display electronic characteristics that suggest their potential usefulness in displacing other cations from cation exchange sites. The results obtained show that extraction of extracellularly bound metal by high concentrations of Ca should be ruled out, as total extraction of Zn was not achieved. Both Hg and Au produced membrane alterations at low concentrations and moreover, neither was more efficient at extracting Zn than the reference extractant (20 mM NiCl2).