A novel and simple method for measuring nano/microplastic concentrations in soil using UV-Vis spectroscopy with optimal wavelength selection.

A simple method for measuring the concentration of nano/microplastics (N/MPs) in soil, which is difficult owing to the size of the filter mesh and the resolution of the measuring instrument, was investigated. A spectrophotometer was used for the measurements and polystyrene particles were used as the N/MP samples. When measuring N/MP concentrations in soil suspensions, absorbance was measured at two wavelengths, and the best combination of wavelengths for measurement was extracted because soil particles and leached components interfere with N/MP absorbance.

Potentially toxic elements pose significant and long-term human health risks in river basin districts with abandoned gold mines.

Gold (Au) mining area is known to be one of the major sources of toxic elements; however, the potential risks of toxic elements from abandoned Au mines to the surrounding river basin districts and human exposure pathways to toxic elements need to be clarified. In this study, the distribution and mobilities of nine toxic elements (As, Cd, Cu, Pb, Sb, Zn, Cr, Ni and V) in Kesennuma City, Tohoku Region in Japan, a typical Au-mining district with several river basins, were studied through a geochemical survey (including element total concentrations and water-/acid-leaching concentrations determinations, as well as GB calculations), and environmental assessment on these elements in soil, river sediment, and river water samples from the study area. The contamination evaluation by index of geo-accumulation (I) and enrichment factor (EF) suggested that As, Cu, Ni and Sb enrichments were greatly observed in the vicinity of the abandoned Au mines; moreover, calculated GB upper values for Cu in the river sediment surpass that of Tohoku Region.

Using data-driven analysis of geochemical environmental information to infer the environmental impact of closed mines.

River sediments have the effect of aggregating geochemical environmental information, such as that related to geological and artificial pollution resulting from mine closure. This information comprises high-dimensional data and is related to the distribution and quantities of elements in river sediments. However, accessing and interpreting this geochemical information can be difficult.

Effects of ferrous iron supplementation on reductive dechlorination of tetrachloroethene and on methanogenic microbial community.

Chloroethenes are common soil and groundwater pollutants. Their dechlorination is impacted by environmental factors, such as the presence of metal ions. We here investigated the effect of ferrous iron on bacterial reductive dechlorination of chloroethenes and on methanogen community.

Data-driven analysis for source apportionment and geochemical backgrounds establishment of toxic elements and REEs in the Tohoku region, Japan.

The Tohoku region of Japan is geologically diverse, with a long agriculture and mining history; however, little information about the origins and distribution mechanisms of elements in this region has been reported. This study aims to provide fundamental insights into the effects of geological features and anthropogenic activities on various elements, including toxic elements and rare-earth elements (REEs), in the Tohoku region. A geochemical database (2007, AIST) consisting of data for 53 elements in 485 river sediment samples from the region was used, and a data-driven method combining principal component analysis (PCA) was applied for analysis.

A Case Study of Natural Attenuation of Chlorinated Solvents Under Unstable Groundwater Conditions in Takahata, Japan.

The natural attenuation behavior of chlorinated solvents and their risks to human health at a contaminated groundwater site in Takahata, Japan, were investigated. It was found that volatile organic compound (VOC) concentrations gradually decreased via two attenuation mechanisms, namely dilution and biodegradation. It was estimated that the VOC concentrations will be below the Japanese limits within 30 years after stopping the active remediation in 2003, which suggests that there is a high possibility that monitored natural attenuation can be adopted as the clean-up method at this contaminated site.

Extraction of heavy metals characteristics of the 2011 Tohoku tsunami deposits using multiple classification analysis.

Tsunami deposits accumulated on the Tohoku coastal area in Japan due to the impact of the Tohoku-oki earthquake. In the study reported in this paper, we applied principal component analysis (PCA) and cluster analysis (CA) to determine the concentrations of heavy metals in tsunami deposits that had been diluted with water or digested using 1 M HCl. The results suggest that the environmental risk is relatively low, evidenced by the following geometric mean concentrations: Pb, 16 mg kg(-1) and 0.

Distribution of dissolved and particulate radiocesium concentrations along rivers and the relations between radiocesium concentration and deposition after the nuclear power plant accident in Fukushima.

This study involved measurement of concentrations of dissolved and particulate radiocesium ((134)Cs and (137)Cs) in river water, and determination of the quantitative relations between the amount of deposited (137)Cs and (137)Cs concentrations in river waters after the Fukushima Daiichi nuclear power plant accident. First, the current concentrations of dissolved and particulate (134)Cs·(137)Cs were determined in a river watershed from 20 sampling locations in four contaminated rivers (Abukuma, Kuchibuto, Shakado, and Ota). Distribution characteristics of different (137)Cs forms varied with rivers.

Comparative study of microbial dechlorination of chlorinated ethenes in an aquifer and a clayey aquitard.

In order to determine whether natural attenuation of chlorinated ethenes by microbial activity occurs in aquitards, sediments at a site contaminated with tetrachloroethene were vertically studied by drilling. The distribution of microbes (Dehalococcoides group and anaerobic hydrogen producers) and the ability of the sediments to sustain microbial dechlorination were determined in an aquitard as well as in an aquifer. Close-spaced sampling revealed the existence of large populations of Dehalococcoides and H(2)-producing bacteria, especially in the organic-rich clayey aquitard rather than in the aquifer.

Non-destructive Analysis of Oil-Contaminated Soil Core Samples by X-ray Computed Tomography and Low-Field Nuclear Magnetic Resonance Relaxometry: a Case Study.

Non-destructive measurements of contaminated soil core samples are desirable prior to destructive measurements because they allow obtaining gross information from the core samples without touching harmful chemical species. Medical X-ray computed tomography (CT) and time-domain low-field nuclear magnetic resonance (NMR) relaxometry were applied to non-destructive measurements of sandy soil core samples from a real site contaminated with heavy oil. The medical CT visualized the spatial distribution of the bulk density averaged over the voxel of 0.

Inhibitory effect of high concentrations of ferric ions on the activity of Acidithiobacillus ferrooxidans.

The influence of high concentrations of ferric ions on the biochemical activity of Acidithiobacillus ferrooxidans was studied using intact cells. The specific oxidation rate of ferrous ions decreased with increasing ferric ion concentration. Lineweaver-Burk plots revealed typical competitive inhibition kinetics, because the slopes varied with the ferric ion concentration.