Influence of agricultural amendments on arsenic biogeochemistry and phytotoxicity in a soil polluted by the destruction of arsenic-containing shells

Arsenic and heavy metals at Japanese abandoned chemical weapons site in China: distribution characterization, source identification and contamination risk assessment

As-containing chemical weapons (CWs) and their degraded products pose a great threat to the environment and to human health. In this study, concentration and distribution characteristics, source identification, and health risk assessments were determined for As, Cr, Ni, Cu, Zn, Cd and Pb in environmental samples from Lianhuapao (LHP), a typical site of Japanese abandoned chemical weapons (JACWs) in China. The results show that the concentration levels of As, Cr and Ni in the LHP soils are abnormally high, with 69.57%, 83.33% and 91.67%, respectively, of the total sample exceeding the risk screening values for soil contamination of agricultural land. As levels in water samples were generally within safety limits, with the exception of perched water in the core contamination area. In the study area, none of the dominant plant species were enriched with As, except for the Pteris vittata L. Pentavalent arsenic was found to be the predominant arsenic species in the topsoil and water samples. Source identification using statistical approaches indicated that the concentrations of As, Pb, Cu, Cd and Zn are likely influenced by JACWs, while Cr and Ni levels may be related to the natural weathering process. The total concentrations of As, Cr and Ni showed a significant degree of contamination, but only As displayed high potential ecological risk. The calculated indexes of health risk evaluation strongly indicate an unacceptable carcinogenic risk (1E-04) to children, and higher non-carcinogenic risk, relative to that of adults. Our data indicate that the health risk from the resulting As contamination is still a cause for concern, although the JACWs were excavated decades ago from these soils.

Loading ferric lignin on polyethylene film and its influence on arsenic-polluted soil and growth of romaine lettuce plant

This work developed a composite (Pe-FeLs) which loaded ferric lignin on polyethylene film (PE film) by chemical modification and physico-chemically characterized by Microscope, FESEM with elemental mapping analysis, and XRD. Microscope pictures showed that chemical modification did not destroy the appearance of PE film. The FESEM images of Pe-FeLs showed the well-distributed clusters could be clearly seen and most of the particles were spherical morphology. Elemental mapping of individual element on Pe-FeLs clearly indicated the existing of iron. The XRD pattern showed the amorphous hydroxides of iron on Pe-FeLs. In arsenic solution, the total arsenic adsorption capacity of Pe-FeLs was much higher than that of ferric lignin and PE, which showed Pe-FeLs had the ability to adsorb arsenic. For making Pe-FeLs work well in the soil, a Pe-FeLs system was set up with plastic grid plate, PE film with holes, Pe-FeLs, PE film, and plastic grid plate from the upper to bottom in order. With applying Pe-FeLs system under the soil, arsenic was significantly reduced by 25.5 ~ 53.4% in heavily, moderately, and lower arsenic-polluted soils, the biomass of the romaine lettuce increased and arsenic accumulation in the romaine lettuce decreased.