Occurrence of 222Rn, 226Ra, 228Ra and U in groundwater in Fujian Province, China

222Rn, 226Ra, 228Ra and U were determined in a total of 552 groundwater samples collected throughout Fujian Province of China. The geometric mean concentrations of 222Rn, 226Ra, 228Ra and total U in the groundwater were 147.8 kBq m-3, 12.7 Bq m-3, 30.2 Bq m-3 and 0.54 microgram kg-1, respectively. High groundwater 222Rn was explained by the predominantly granitic rock aquifers in Fujian. A lifetime risk of 1.7 x 10(-3) was estimated for the ingestion of groundwater 222Rn. High ratios of 228Ra to 226Ra contents (geometric mean of 2.4) and their disproportion suggest that 228Ra should also be measured in the assessment of population doses from drinking water in the regions of high rock or soil 232Th. No significant correlation between the 222Rn concentrations in groundwater and air was found.     

Carbon disulfide at a Chinese viscose factory external and internal exposure assessment

This article presents the results of carbon disulfide exposure measurements in a Chinese viscose rayon factory. The objectives of the study were to identify the external exposure levels at a large factory and to investigate the 2-thiothiazolidine-4-carboxylic acid (TTCA) concentrations in the urine of the subjects who were exposed to carbon disulfide in the working place atmosphere. The metabolism of carbon disulfide in the exposed subjects was also studied in order to demonstrate the best points in time for the internal exposure sampling. The measurement of the amount of personal exposure to carbon disulfide in the air of the workplace was performed by GC-FPD; the presence of TTCA in the workers urine was analyzed by use of a modified HPLC method. The kinetics of TTCA excretion was studied by analyses at different time-points both during and after exposure to carbon disulfide in the subjects. A total of 155 personal samples were obtained. The carbon disulfide concentration in the staple viscose hall was 13.72 +/- 1.12 mg m-3 in terms of the geometric mean +/- geometric standard deviation, and was 20.05 +/- 1.33 mg m-3 in the filament spinning hall. The TTCA values in the subjects who worked in the staple spinning hall were 1.18 +/- 0.43 mg g-1 creatinine and 1.07 +/- 0.38 mg g-1 creatinine for subjects working in the filament spinning hall. The best time for TTCA sampling is at the end of the working shift, the TTCA excretion was stable for a period of 4-12 h after exposure of the subjects to the carbon disulfide. It might be that the Chinese have different anthropometric characteristics; a sampling bias may therefore appear among different races.     

Effects of Acid Rain on Competitive Releases of Cd, Cu, and Zn from Two Natural Soils and Two Contaminated Soils in Hunan, China

Leaching experiments of rebuilt soil columns with two simulated acid rain solutions (pH 4.6–3.8) were conducted for two natural soils and two artificial contaminated soils from Hunan, south-central China, to study effects of acid rain on competitive releases of soil Cd, Cu, and Zn. Distilled water was used in comparison. The results showed that the total releases were Zn>Cu>Cd for the natural soils and Cd>Zn≫Cu for the contaminated soils, which reflected sensitivity of these metals to acid rain. Leached with different acid rain, about 26–76% of external Cd and 11–68% external Zn were released, but more than 99% of external Cu was adsorbed by the soils, and therefore Cu had a different sorption and desorption pattern from Cd and Zn. Metal releases were obviously correlated with releases of TOC in the leachates, which could be described as an exponential equation. Compared with the natural soils, acid rain not only led to changes in total metal contents, but also in metal fraction distributions in the contaminated soils. More acidified soils had a lower sorption capacity to metals, mostly related to soil properties such as pH, organic matter, soil particles, adsorbed SO₄ ²⁻, exchangeable Al³⁺ and H⁺, and contents of Fe₂O₃ and Al₂O₃.     

改进的灰色关联分析在滑坡危险性评价中的应用——以广东省滑坡危险性评价为例

利用改进的灰色关联分析方法,采用“中心化”无量纲的处理方法,对广东滑坡灾害危险性的影响因素进行灰色关联度分析。通过地形地貌条件、地层岩性特征、地质构造特征、岩土体结构特性、水文地质条件、植被覆盖率、降雨分布、地震、人类经济工程活动等9个评价因素与滑坡危险性的关联度计算,得出各影响因素与滑坡危险性评价的关系,具有一定的客观性、科学性和合理性。     

Arsenic stabilization by zero-valent iron,bauxite residue,and zeolite at a contaminated site planting Panax notoginseng

Panax notoginseng (Burk.) F.H. Chen, a rare traditional Chinese medicinal herb, is a widely used phytomedicine used all over the world. In recent years, the arsenic contamination of the herb and its relative products becomes a serious problem due to elevated soil As concentration. This study aimed to evaluate the effects of different types and dosages of amendments on As stabilization in soil and its uptake by P. notoginseng. Results showed that comparing to control treatment, the As concentrations of P. notoginseng declined by 49–63%, 43–61% and 52–66% in 0.25% zero-valent iron (Fe(0)), 0.5% bauxite residue, and 1% zeolite treatment, respectively; whereas the biomasses were elevated by 62–116%, 45–152% and 114–265%, respectively. The As(III) proportions of P. notoginseng increased by 8%, 9%, and 8%, and the transfer factors of As from root to shoot increased by 37%, 42% and 84% in the optimal treatments of Fe(0), bauxite residue, and zeolite. For soil As, all the three amendments could transform the non-specifically adsorbed As fraction to hydrous oxides Fe/Al fractions (by Fe(0) and red mud) or specifically adsorbed As fraction (by zeolite), therefore reduced the bioavailability of soil As. With a comprehensive consideration of stabilization efficiency, plant growth, environmental influence, and cost, Fe(0) appeared to be the best amendment, and zeolite could also be a good choice. In conclusion, this study was of significance in developing As contamination control in P. notoginseng planting areas, and even other areas for medicinal herb growing.     

Removal of organic toxic chemicals using the spent mushroom compost of Ganoderma lucidum

The removal of the organic toxic chemicals di-n-butyl phthalate (DBP), di-2-ethyl hexyl phthalate (DEHP), nonylphenol (NP), and bisphenol-A (BPA) by laccase obtained from the spent mushroom compost (SMC) of the white rot fungi, Ganoderma lucidum, was investigated. The optimal conditions for the extraction of laccase from SMC required using sodium acetate buffer (pH 5.0, solid : solution ratio 1 : 5), and extraction over 3 h at 4 °C. The removal of NP was enhanced by adding CuSO(4) (1 mM), MnSO(4) (0.5 mM), tartaric acid (20 mM), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS; 1 mM), and 1-hydroxybenzotriazole (HBT; 20 mg L(-1)), with ABTS yielding a higher NP removal efficiency than the other additives. At a concentration of 2 mg L(-1), DBP, DEHP, NP, and BPA were almost entirely removed by laccase after incubation for 1 day. The removal efficiencies, in descending order of magnitude, were DBP > BPA > NP > DEHP. We believe that these findings could provide useful information for improving the efficiency of the removal of organic toxic chemicals in the environment.