掺杂La3+纳米ZnO的制备及其光催化性能

采用共沉淀法制备了不同La3＋含量的La3＋-ZnO催化剂,采用x射线衍射仪、透射电子显微镜等对催化剂的结构、相组成、形貌和粒径进行了表征,比较了不同La3＋含量的La3＋-ZnO催化剂对罗丹明B降解率的影响。实验结果表明,掺杂La3＋导致ZnO粒径减小,比表面积增大,延长了光生电子-空穴对的寿命,提高了ZnO的光量子产率,La3＋-ZnO催化剂的光催化活性比ZnO显著增强。La3＋质量分数为0．8％时,罗丹明B降解率最高,为92．5％。经La3＋质量分数0．8％的La3＋-ZnO催化剂降解后罗丹明B已被完全降解为无机小分子。     

The geostatistic-based spatial distribution variations of soil salts under long-term wastewater irrigation

The purpose of this study was to determine and evaluate the spatial changes in soil salinity by using geostatistical methods. The study focused on the suburb area of Beijing, where urban development led to water shortage and accelerated wastewater reuse to farm irrigation for more than 30 years. The data were then processed by GIS using three different interpolation techniques of ordinary kriging (OK), disjunctive kriging (DK), and universal kriging (UK). The normality test and overall trend analysis were applied for each interpolation technique to select the best fitted model for soil parameters. Results showed that OK was suitable for soil sodium adsorption ratio (SAR) and Na⁺ interpolation; UK was suitable for soil Cl^? and pH; DK was suitable for soil Ca²⁺. The nugget-to-sill ratio was applied to evaluate the effects of structural and stochastic factors. The maps showed that the areas of non-saline soil and slight salinity soil accounted for 6.39 and 93.61 %, respectively. The spatial distribution and accumulation of soil salt were significantly affected by the irrigation probabilities and drainage situation under long-term wastewater irrigation.     

树皮在大气有机氯农药监测中应用的研究进展

有机氯农药(Organochlorine pesticides,OCPs)曾在全世界被大量使用,即使禁用多年,仍能在各种环境介质中被广泛检出,对生态环境和人体健康存在着潜在的威胁。因此OCPs的环境迁移和归趋一直是该领域的研究热点。树皮是一种天然的被动采样器,能够很好的反映出大气有机物长期的污染程度。本文简要论述了树皮作为被动采样器在大气污染物监测研究中应用的优势,并对OCPs在树皮中的残留浓度、特征及影响其富集的因素进行了探讨,最后特别针对具有手性的OCPs在树皮中的对映体选择性特征进行了评述。     

Mercury release during thermal treatment of two Chinese coal gangues

The utilization of coal gangue in power plants has become a new anthropogenic discharge source of mercury and attracted much concern in China. It is crucial to obtain the information about the mercury release during thermal treatment of coal gangue. In this study, the mercury release behavior of two coal gangues selected from two power plants were studied under different thermal treatment conditions of heating rate, residence time, and atmosphere. The results of mercury release profile show that the specified release temperature ranges for the different modes of occurrence of Hg are scarcely affected by the heating rate of 10, 20, and 40 °C/min. A higher heating rate could promote the Hg release to some extent. The mercury release ratio gradually increases with the extension of residence time for both coal gangues. The oxidizing environment has a positive effect on mercury release < 600 °C and has a minor effect > 600 °C. Mercury in coal gangue is more volatile than coal gangue matrix and the mercury in GD coal gangue is more easily released out than that in ED coal gangue.     

Bioavailability evaluation,uptake of heavy metals and potential health risks via dietary exposure in urban-industrial areas

A verity of human activities i.e. urbanization and industrialization have been resulted serious environmental contaminations by heavy metals in all over the world. The settlement of populations in urban and nearby industrial areas for economic development has significant share in their exposure to these metallic contaminants. Depending on the nature and type of the pollutants, targeted urban-industrial environments can have harmful and chronic health risk impacts on exposed local inhabitants and may require detoxification, healing and remedial therapy. Consequently, environmental monitoring as well as human health risk assessments of urban environments under industrial influence are key dominant features. We believe this work will provide new insights into the studies of metals exposure and associated health risks in emerging industrials cities of developing countries. Present study aimed to study the bioavailability of metals, quantify the changeability in soil and vegetable metal concentrations and estimation of human health risks via dietary exposure, focusing on urban-industrial environment. Soil and vegetable samples were collected in six random sites within the urban, periurban and industrial areas and analyzed for metal concentrations. In addition, risk assessment model proposed by US-EPA was employed to estimate the potential health risk of heavy metals via dietary intake. Results indicated that the heavy metal concentrations were noteworthy in periurban and urban-industrial areas. However, contamination levels varied with the type of vegetable, and the point source pollution such as traffic, urban wastes and industrial effluent. According to the estimated THQ and HI values for non-carcinogenic risk, little or no negative impact of heavy metals was observed on local inhabitants. However, the concentrations of Cr, Cd, Pb and Ni were nearly closed to the permissible limits described by US-EPA in urban-industrial areas. Conclusively, some efficient remedial strategies should be focus to overcome the increasing levels of Cr, Cd, Pb and Ni in this study area to protect the health of local inhabitants.     

Deriving sorption indices for the prediction of potential phosphorus loss from calcareous soils

The aim of this study was to develop techniques to evaluate soil phosphorus (P) sorption capacity (PSC) and determine critical soil P levels to predict P loss potential for calcareous soils. Seventy-five soils mostly from Northern China were analyzed for soil P using four extraction methods (water, P_w; carbonate, P_Ols; ammonium oxalate, P_ox; and Mehlich 3, P_M3) as well as PSC derived from single-point (PSC₁₅₀) and multipoint sorption (S _t) isotherms. Strong correlation was found between PSC₁₅₀ and S _t (r ²=0.89, p<0.001). The sum of αCa_M3 and βMg_M3 as an index of PSC (PSC_{(CaM3 + MgM3)}) was most closely related to the maximum amount of P sorbed (S _max) as given by the sum of S _t and soil initial P setting α=0.039 and β=0.462 (r ²=0.80, p<0.001). The degree of P saturation (DPS) was thereafter calculated from PSC_{(CaM3 + MgM3)} (DPS_{(CaM3 + MgM3)}), to which Olsen P (P_Ols) was significantly correlated (r ²=0.82, p<0.001). In a split-line regression from P_w against DPS_{(CaM3 + MgM3)} (r ²=0.87, p<0.05), a change point was identified at 28.1% DPS_{(CaM3 + MgM3)}, which was equivalent to 49.2 mg kg^?1 P_Ols and corresponded to a P_w concentration of 8.8 mg kg^?1. After the change point, a sharp increase in P_w was observed. Our results reveal a new approach to approximating DPS from Ca_M3 and Mg_M3 for calcareous soils without the need to generate a S _max. We conclude that in the absence of an environmental soil test criteria for P, the DPS_{(CaM3 + MgM3)} and P_Ols could be used to predict P loss potential from calcareous soils.     

Characteristics of water-soluble inorganic ions in PM2.5 and PM2.5–10 in the coastal urban agglomeration along the Western Taiwan Strait Region,China

PM_2.5 and PM_2.5–10 aerosol samples were collected in four seasons during November 2010, January, April, and August 2011 at 13 urban/suburban sites and one background site in Western Taiwan Straits Region (WTSR), which is the coastal area with rapid urbanization, high population density, and deteriorating air quality. The 10 days average PM_2.5 concentrations were 92.92, 51.96, 74.48, and 89.69 μg/m³ in spring, summer, autumn, and winter, respectively, exceeding the Chinese ambient air quality standard for annual average value of PM_2.5 (grade II, 35 μg/m³). Temporal distribution of water-soluble inorganic ions (WSIIs) in PM_2.5 was coincident with PM_2.5 mass concentrations, showing highest in spring, lowest in summer, and middle in autumn and winter. WSIIs took considerable proportion (42.2～50.1 %) in PM_2.5 and PM_2.5–10. Generally, urban/suburban sites had obviously suffered severer pollution of fine particles compared with the background site. The WSIIs concentrations and characteristics were closely related to the local anthropogenic activities and natural environment, urban sites in cities with higher urbanization level, or sites with weaker diffuse condition suffered severer WSIIs pollution. Fossil fuel combustion, traffic emissions, crustal/soil dust, municipal constructions, and sea salt and biomass burnings were the major potential sources of WSIIs in PM_2.5 in WTSR according to the result of principal component analysis.     

Health risk assessment of exposure to organic matter from the use of reclaimed water in toilets

To estimate the carcinogenic and non-carcinogenic risks of six volatile organic compounds (VOCs) found in reclaimed water used for flushing toilets, a probabilistic health risk assessment based on Monte Carlo simulations was used. Before Monte Carlo simulations, the contaminant volatilization model was applied to estimate the concentration of the pollutants in air. Moreover, a questionnaire was used to acquire daily exposure time and the Batch Fit tool of Crystal Ball software was applied to find the best-fitting distribution of a part of the input parameters. The risk analysis indicated that the health risks from six VOCs were lower than the negligible risk level (1?×?10^?8) in all cases, and the health risk for females was slightly higher than that for males. Overall, exposure to organic pollutants in reclaimed water during toilet flushing does not currently pose a significant carcinogenic risk to humans. In this study, we want to provide some information on the health risk from reclaimed water used for toilet flushing in China and hope that it will be useful to promote the application of reclaimed water in water-deficient areas.     

Physiological and biochemical responses of rice seeds to phosphine exposure during germination

Rice seeds (Tianyou, 3618) were used to examine the physiological and biochemical responses to phosphine exposure during germination. A control (0 mg m⁻³) and four concentrations of phosphine (1.4 mg m⁻³, 4.2 mg m⁻³, 7.0 mg m⁻³ and 13.9 mg m⁻³) were used to treat the rice seeds. Each treatment was applied for 90 min once per day for five days. The germination rate (GR); germination potential (GP); germination index (GI); antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT); and lipid peroxidation measured through via malondialdehyde (MDA) were determined as indicators of the physiological and biochemical responses of the rice seeds to phosphine exposure. These indicators were determined once per day for five days. The results indicated that the GR, GP and GI of the rice seeds markedly decreased after phosphine exposure. The changes in the activities of the antioxidant enzymes due to the phosphine exposure were also significant. The exposure lowered the CAT and SOD activities and increased POD activity in the treated rice seeds compared with controls. The MDA content exhibited a slow increase trend with the increase of phosphine concentration. These results suggest that phosphine has inhibitory effects on seed germination. In addition, phosphine exposure caused oxidative stress in the seeds. The antioxidant enzymes could play a pivotal role against oxidative injury. Overall, the effect of phosphine on rice seeds is different from what has been reported previously for insects and mammals.