The dynamics of mercury near Idrija mercury mine, Slovenia: Horizontal and vertical distributions of total, methyl, and ethyl mercury concentrations in soils.

The distributions of the total mercury (T-Hg), methylmercury (MeHg), and ethylmercury (EtHg) concentrations in soil and their relationship to chemical composition of the soil and total organic carbon content (TOC, %) were investigated. Core samples were collected from hill slope on the right and left riverbanks of the Idrija River. Former smelting plant is located on the right bank. The T-Hg average in each of the core samples ranged from 0.25 to 1650 mg kg-1. The vertical T-Hg variations in the samples from the left bank showed no significant change with depth. Conversely, the T-Hg varied with depth, with the surface, or layers several centimeters from the surface, tending to show the highest values in the samples from the right bank. Since the right and left bank soils have different chemical compositions, different pathways of mercury delivery into soils were suggested. The MeHg and EtHg concentrations ranged from n.d. (not detected) to 444 µg kg-1 and n.d. to 17.4 µg kg-1, respectively. The vertical variations of MeHg and EtHg were similar to those of TOC, except for the near-surface layers containing TOC greater than 20%. These results suggest that the decomposition of organic matter is closely related to organic mercury formation.

Distribution of total mercury and methylmercury around the small-scale gold mining area along the Cikaniki River, Bogor, Indonesia.

This study investigates the distribution of total mercury (T-Hg) and methylmercury (MeHg) in the soil and water around the artisanal and small-scale gold mining (ASGM) area along the Cikaniki River, West Java, Indonesia. The concentration of T-Hg and MeHg in the forest soil ranged from 0.07 to 16.7 mg kg-1 and from <0.07 to 2.0 µg kg-1, respectively, whereas it ranged from 0.40 to 24.9 mg kg-1 and from <0.07 to 56.3 µg kg-1, respectively, in the paddy field soil. In the vertical variation of the T-Hg of forest soil, the highest values were observed at the soil surface, and these values were found to decrease with increasing depth. A similar variation was observed for MeHg and total organic carbon content (TOC), and a linear relationship was observed between them. Mercury deposited on the soil surface can be trapped and retained by organic matter and subjected to methylation. The slope of the line obtained for the T-Hg vs. TOC plot became larger near the ASGM villages, implying a higher rate of mercury deposition in these areas. In contrast, the plots of MeHg vs. TOC fell along the same trend line regardless of the distance from the ASGM village. Organic carbon content may be a predominant factor in controlling MeHg formation in forest soils. The T-Hg concentration in the river water ranged from 0.40 to 9.6 µg L-1. River water used for irrigation can prove to be a source of mercury for the paddy fields. The concentrations of Hg0 and Hg2+ in river water showed similar variations as that observed for the T-Hg concentration. The highest Hg0 concentration of 3.2 µg L-1 can be attributed to the waste inflow from work sites. The presence of Hg0 in river water can become a source of mercury present in the atmosphere along the river. MeHg concentration in the river water was found to be 0.004-0.14% of T-Hg concentration, which was considerably lower than the concentrations of other Hg species. However, MeHg comprised approximately 0.2% of the T-Hg in paddy field soil. Mercury deposited from the atmosphere and the river water can be subjected to methylation. Paddy fields are very important ecosystems; therefore, the effect of MeHg on these ecosystems and human beings should be further investigated.

Low level mercury uptake by plants from natural environments--mercury distribution in Solidago altissima L.-.

In order to elucidate the participation of plants in the biogeochemical cycling of mercury in natural environments, total mercury contents in leaves, stems and roots of tall goldenrod (Solidago altissima L.), Compositae, were determined. The mercury content in stems was considerably lower than that in leaves and roots. A positive correlation of mercury content was observed between soil and roots. The leaves at the lower part of the plant tended to have a higher concentration of mercury than the upper leaves. However, the mercury content of the leaves was independent of that in the soil. These observations suggested that the leaves of the plant can accumulate environmental mercury, but the mercury does not come from the soil via the root and stems. The mercury in leaves might originate predominantly from ambient air. The mercury in the leaves accumulated from the air can be delivered to the soil when the leaves fall. The roots also can adsorb the mercury from the soil; however, the mercury does not move from the roots and is not released into the air via the plant body.

Vertical variations in the concentration of mercury in soils around Sakurajima Volcano, Southern Kyushu, Japan.

In an effort to estimate the influence of mercury emitted from Sakurajima Volcano, Southern Kyushu, Japan, on the accumulation of mercury in soil, the vertical distribution of total mercury in soils was investigated together with organic matter content and grain size. The soils were sampled at a thickness of 1 cm from the surface to depth of 1 m at five locations on Sakurajima and two control locations, i.e. Takatoge approximately 11 km southeast and Suzuyama 22 km southwest of the volcano. The concentration in soils increased with the distance from the volcano and was 6.5+/-1.9 ngg(-1) (n=335), 29.0+/-15.6 ngg(-1) (n=100) and 229+/-105 ngg(-1) (n=103) for Sakurajima, Takatoge and Suzuyama, respectively. The concentration of mercury correlated with the amount of organic matter, but not with grain size distribution. The sedimentation rate for Sakurajima, Takatoge and Suzuyama was estimated from geological data to be approximately 1.3, 0.083 and 0.0048 cmyear(-1), respectively. The relatively fast sedimentation of Sakurajima soil was caused by the frequent precipitation of volcanic ash. The annual deposition of mercury estimated for Sakurajima, Takatoge and Suzuyama from the mercury concentration, sedimentation rate and soil density was 9 x 10(4), 3 x 10(4) and 2 x 10(4) ngm(-2)year(-1), respectively. Although the soil of Sakurajima had the lowest concentration among the three sites, it received the largest amount of mercury.