Simultaneous adsorption and degradation of Zn2+ and Cu2+ from wastewaters using nanoscale zero-valent iron impregnated with clays

Clays such as kaolin, bentonite and zeolite were evaluated as support material for nanoscale zero-valent iron (nZVI) to simultaneously remove Cu²⁺ and Zn²⁺ from aqueous solution. Of the three supported nZVIs, bentonite-supported nZVI (B-nZVI) was most effective in the simultaneous removal of Cu²⁺ and Zn²⁺ from a aqueous solution containing a 100 mg/l of Cu²⁺ and Zn²⁺, where 92.9 % Cu²⁺ and 58.3 % Zn²⁺ were removed. Scanning electronic microscope (SEM) revealed that the aggregation of nZVI decreased as the proportion of bentonite increased due to the good dispersion of nZVI, while energy dispersive spectroscopy (EDS) demonstrated the deposition of copper and zinc on B-nZVI after B-nZVI reacted with Cu²⁺ and Zn²⁺. A kinetics study indicated that removing Cu²⁺ and Zn²⁺ with B-nZVI accorded with the pseudo first-order model. These suggest that simultaneous adsorption of Cu²⁺and Zn²⁺ on bentonite and the degradation of Cu²⁺and Zn²⁺ by nZVI on the bentonite. However, Cu²⁺ removal by B-nZVI was reduced rather than adsorption, while Zn²⁺ removal was main adsorption. Finally, Cu²⁺, Zn²⁺, Ni²⁺, Pb²⁺ and total Cr from various wastewaters were removed by B-nZVI, and reusability of B-nZVI with different treatment was tested, which demonstrates that B-nZVI is a potential material for the removal of heavy metals from wastewaters.     

Approximation and spatial regionalization of rainfall erosivity based on sparse data in a mountainous catchment of the Yangtze River in Central China

In densely populated countries like China, clean water is one of the most challenging issues of prospective politics and environmental planning. Water pollution and eutrophication by excessive input of nitrogen and phosphorous from nonpoint sources is mostly linked to soil erosion from agricultural land. In order to prevent such water pollution by diffuse matter fluxes, knowledge about the extent of soil loss and the spatial distribution of hot spots of soil erosion is essential. In remote areas such as the mountainous regions of the upper and middle reaches of the Yangtze River, rainfall data are scarce. Since rainfall erosivity is one of the key factors in soil erosion modeling, e.g., expressed as R factor in the Revised Universal Soil Loss Equation model, a methodology is needed to spatially determine rainfall erosivity. Our study aims at the approximation and spatial regionalization of rainfall erosivity from sparse data in the large (3,200 km²) and strongly mountainous catchment of the Xiangxi River, a first order tributary to the Yangtze River close to the Three Gorges Dam. As data on rainfall were only obtainable in daily records for one climate station in the central part of the catchment and five stations in its surrounding area, we approximated rainfall erosivity as R factors using regression analysis combined with elevation bands derived from a digital elevation model. The mean annual R factor (R _a) amounts for approximately 5,222 MJ?mm?ha^?1?h^?1?a^?1. With increasing altitudes, R _a rises up to maximum 7,547 MJ?mm ha^?1?h^?1 a^?1 at an altitude of 3,078 m a.s.l. At the outlet of the Xiangxi catchment erosivity is at minimum with approximate R _a?=?1,986 MJ?mm?ha^?1?h^?1?a^?1. The comparison of our results with R factors from high-resolution measurements at comparable study sites close to the Xiangxi catchment shows good consistance and allows us to calculate grid-based R _a as input for a spatially high-resolution and area-specific assessment of soil erosion risk.     

湿地生态系统基质重金属积累与酶活性的研究现状

湿地生态系统具有净化污水的功能,因其具有高效低耗等优点,在污水处理方面极具开发应用前景,而基质作为湿地生态系统重要组成部分,已成为众多学者的研究热点。本文综合分析了湿地生态系统基质中重金属积累和酶活性的时空分布及影响因素的研究现状,并对相关研究提出了新的认识与展望,以期为湿地生态系统基质去除废水中重金属的深入研究和应用提供综合分析资料。     

Phosphine in paddy fields and the effects of environmental factors

Ambient levels of phosphine (PH₃) in the air, phosphine emission fluxes from paddy fields and rice plants, and the distribution of matrix-bound phosphine (MBP) in paddy soils were investigated throughout the growing stages of rice. The relationships between MBP and environmental factors were analyzed to identify the principal factors determining the distribution of MBP. The phosphine ambient levels ranged from 2.368 ± 0.6060 ng m⁻³ to 24.83 ± 6.529 ng m⁻³ and averaged 14.25 ± 4.547 ng m⁻³. The highest phosphine emission flux was 22.54 ± 3.897 ng (m² h)⁻¹, the lowest flux was 7.64 ± 4.83 ng (m² h)⁻¹, and the average flux was 14.17 ± 4.977 ng (m² h)⁻¹. Rice plants transport a significant portion of the phosphine emitted from the paddy fields. The highest contribution rate of rice plants to the phosphine emission fluxes reached 73.73% and the average contribution was 43.00%. The average MBP content of 111.6 ng kg⁻¹fluctuated significantly in different stages of rice growth and initially increased then decreased with increasing depth. The peak MBP content in each growth stage occurred approximately 10 cm under the surface of paddy soils. Pearson correlation analyses and stepwise multiple regression analysis showed that soil temperature (Ts), acid phosphatase (ACP) and total phosphorus (TP) were the principal environmental factors, with correlative rankings of Ts > ACP > TP.     

A human health risk assessment of rare earth elements in soil and vegetables from a mining area in Fujian Province,Southeast China

Contaminated food through dietary intake has become the main potential risk impacts on human health. This study investigated concentrations of rare earth elements (REEs) in soil, vegetables, human hair and blood, and assessed human health risk through vegetables consumption in the vicinity of a large-scale mining area located in Hetian Town of Changting County, Fujian Province, Southeast China. The results of the study included the following mean concentrations for total and bio-available REEs of 242.92 ± 68.98 (135.85–327.56) μg g⁻¹ and 118.59 ± 38.49 (57.89–158.96) μg g⁻¹ dry weight (dw) in agricultural soil, respectively, and total REEs of 3.58 ± 5.28 (0.07–64.42) μg g⁻¹ dw in vegetable samples. Concentrations of total REEs in blood and hair collected from the local residents ranged from 424.76 to 1274.80 μg L⁻¹ with an average of 689.74 ± 254.25 μg L⁻¹ and from 0.06 to 1.59 μg g⁻¹ with an average of 0.48 ± 0.59 μg g⁻¹ of the study, respectively. In addition, a significant correlation was observed between REEs in blood and corresponding soil samples (R² = 0.6556, p < 0.05), however there was no correlation between REEs in hair and corresponding soils (p > 0.05). Mean concentrations of REEs of 2.85 (0.59–10.24) μg L⁻¹ in well water from the local households was 53-fold than that in the drinking water of Fuzhou city (0.054 μg L⁻¹). The health risk assessment indicated that vegetable consumption would not result in exceeding the safe values of estimate daily intake (EDI) REEs (100−110 μg kg⁻¹ d⁻¹) for adults and children, but attention should be paid to monitoring human beings health in such rare earth mining areas due to long-term exposure to high dose REEs from food consumptions.     

企业社会资本研究

社会资本是指行动主体通过社会网络摄取稀缺资源并由此获益的能力.本文界定了企业社会资本的内涵、特征和功能,指出企业社会资本是企业建立在规范和信任基础上的,通过社会网络摄取稀缺资源的能力,它能够给企业带来收益,促进企业实现其目标.     

Fungicidal values of bio-oils and their lignin-rich fractions obtained from wood/bark fast pyrolysis

Pine wood, pine bark, oak wood and oak bark were pyrolyzed in an auger reactor. A total of 16 bio-oils or pyrolytic oils were generated at different temperatures and residence times. Two additional pine bio-oils were produced at the National Renewable Energy Laboratory in a fluidized-bed reactor at different temperatures. All these bio-oils were fractionated to obtain lignin-rich fractions which consist mainly of phenols and neutrals. The pyrolytic lignin-rich fractions were obtained by liquid-liquid extraction. Whole bio-oils and their lignin-rich fractions were studied as potential environmentally benign wood preservatives to replace metal-based CCA and copper systems that have raised environmental concerns. Each bio-oil and several lignin-rich fractions were tested for antifungal properties. Soil block tests were conducted using one brown-rot fungus (Gloeophyllum trabeum) and one white-rot fungus (Trametes versicolor). The lignin-rich fractions showed greater fungal inhibition than whole bio-oils for a impregnation solution 10% concentration level. Water repellence tests were also performed to study wood wafer swelling behavior before and after bio-oil and lignin-rich fraction treatments. In this case, bio-oil fractions did not exhibit higher water repellency than whole bio-oils. Comparison of raw bio-oils in soil block tests, with unleached wafers, at 10% and 25% bio-oil impregnation solution concentration levels showed excellent wood preservation properties at the 25% level. The good performance of raw bio-oils at higher loading levels suggests that fractionation to generate lignin-rich fractions is unnecessary. At this more effective 25% loading level in general, the raw bio-oils performed similarly. Prevention of leaching is critically important for both raw bio-oils and their fractions to provide decay resistance. Initial tests of a polymerization chemical to prevent leaching showed some success.     

水体环境中氟喹诺酮类药物的污染现状及分析方法

阐述了水体环境中的氟喹诺酮类（FQs）药物的来源和污染现状,介绍了FQs在水体环境中的迁移、转化和转归途径,归纳了各种当前使用较多的FQs分析检测方法的功能特点和适用条件。指出今后在FQs分析技术的开发上,应注重提高检测容量、降低检出限和削减环境负面影响因素。     

在混合表面活性剂存在下锗和口底唑的胶束增溶分光光度法的研究

研究了以ＣＴＡＢ联用乳化剂ＯＰ,锗和口底唑的显色反应。结果表明,在ｐＨ５～６的酸度范围内及波长５０５ｎｍ处,络合物呈最大吸收,表观摩尔吸光系数为８１×１０４。用两种不同的方法研究了络合物的组成,组成比为Ｇｅ（Ⅳ）∶口底唑＝１∶３。本体系在０～１６０μｇＧｅ／２５ｍｌ范围内遵守比尔定律。本法使用混合掩蔽剂,提高了方法的选择性,并用于环境水样中锗的回收试验和阳极泥中锗的测定,得到了较好的结果