Rapid detection of soils contaminated with heavy metals and oils by laser induced breakdown spectroscopy (LIBS).

A laser induced breakdown spectroscopy (LIBS) coupled with the chemometric method was applied to rapidly discriminate between soils contaminated with heavy metals or oils and clean soils. The effects of the water contents and grain sizes of soil samples on LIBS emissions were also investigated. The LIBS emission lines decreased by 59-75% when the water content increased from 1.2% to 7.8%, and soil samples with a grain size of 75 µm displayed higher LIBS emission lines with lower relative standard deviations than those with a 2mm grain size. The water content was found to have a more pronounced effect on the LIBS emission lines than the grain size. Pelletizing and sieving were conducted for all samples collected from abandoned mining areas and military camp to have similar water contents and grain sizes before being analyzed by the LIBS with the chemometric analysis. The data show that three types of soil samples were clearly discerned by using the first three principal components from the spectral data of soil samples. A blind test was conducted with a 100% correction rate for soil samples contaminated with heavy metals and oil residues.

Bioaccumulation and the soil factors affecting the uptake of arsenic in earthworm, Eisenia fetida.

To better understand arsenic (As) bioaccumulation, a soil invertebrate species was exposed to 17 field soils contaminated with arsenic due to mining activity. Earthworms (Eisenia fetida) were kept in the soils for 70 days under laboratory conditions, as body burden increased and failed to reach equilibrium in all soils. After 70 days of exposure, XANES spectra determined that As was biotransformed to a highly reduced form. Uptake kinetics for As was calculated using one compartment model. Stepwise multiple regression suggested that sorbed As in soils are bioaccessible, and uptake is governed by soil properties (iron oxide, sulfate, and dissolved organic carbon) that control As mobility in soils. As in soil solution are highly related to uptake rate except four soils which had relatively high chloride or phosphate. The results imply that uptake of As is through As interaction with soil characteristics as well as direct from the soil solution. Internal validation showed that empirically derived regression equations can be used for predicting As uptake as a function of soil properties within the range of soil properties in the data set.

Arsenic detoxification potential of aox genes in arsenite-oxidizing bacteria isolated from natural and constructed wetlands in the Republic of Korea.

Arsenic is subject to microbial interactions, which support a wide range of biogeochemical transformations of elements in natural environments such as wetlands. The arsenic detoxification potential of the bacterial strains was investigated with the arsenite oxidation gene, aox genotype, which were isolated from the natural and constructed wetlands. The isolates were able to grow in the presence of 10 mM of sodium arsenite (As(III) as NaAsO(2)) and 1 mM of D: +glucose. Phylogenetic analysis based on 16S rRNA gene sequencing indicated that these isolated strains resembled members of the genus that have arsenic-resistant systems (Acinetobacter sp., Aeromonas sp., Agrobacterium sp., Comamonas sp., Enterobacter sp., Pantoea sp., and Pseudomonas sp.) with sequence similarities of 81-98%. One bacterial isolate identified as Pseudomonas stutzeri strain GIST-BDan2 (EF429003) showed the activity of arsenite oxidation and existence of aoxB and aoxR gene, which could play an important role in arsenite oxidation to arsenate. This reaction may be considered as arsenic detoxification process. The results of a batch test showed that P. stutzeri GIST-BDan2 (EF429003) completely oxidized in 1 mM of As(III) to As(V) within 25-30 h. In this study, microbial activity was evaluated to provide a better understanding of arsenic biogeochemical cycle in both natural and constructed wetlands, where ecological niches for microorganisms could be different, with a specific focus on arsenic oxidation/reduction and detoxification.

Occupations and Parkinson's disease: a multi-center case-control study in South Korea.

OBJECTIVE: We performed a hospital based case-control study in South Korea (1) to clarify the role of occupational exposure, and especially manganese (Mn) exposure in the etiology of Parkinson's disease (PD) and (2) to discover the association between any occupations and PD. METHODS: We selected two groups, PD patient group (N1) and controls (N2). Three hundred sixty-seven consecutive outpatients with PD (177 men, 190 women) and 309 controls were interviewed about life style, past history, family history, education level, and occupational history etc. We employed a range of industrial categories as defined by section (the most broad category) and division (sub-category) of the Korea Standard Industry Code (KSIC) Manual. Along with KSIC, we also used the Korea Standard Classification of Occupations (KSCO) as proxies of occupational exposure. The odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for age, sex, smoking status, and education level are presented. RESULTS: As regarding the exposure to hazardous materials, especially Mn, more subjects in the control group than the PD patient group have worked in the occupations with potential exposure to Mn (P < 0.001). Ever having worked in 'agriculture, hunting, and forestry' section of industry was positively associated with PD (OR 1.88), and 'agriculture production crops (OR 1.96)' division of industry was positively associated with PD. On the other hand, ever having worked in the 'manufacturing (OR 0.56)', 'transportation (OR 0.28)' section of industry, and 'transporting (OR 0.20)' division of industry were negatively associated with PD. 'Drivers (OR 0.13)' division of occupation also was negatively associated with PD. CONCLUSIONS: To our knowledge, this is the first case-control studies to find an inverse relationship between 'transporting' or 'technicians like machinery engineers' as his/her longest job and PD risk. Because of this unexpected finding, our work should be replicated in various populations.