钙、氯对磷酸盐稳定污染土壤中铅的促进作用研究

为探讨促进磷酸盐稳定污染土壤中铅的方法,在全铅含量为517 mg·kg-1的铅冶炼污染土壤中加入5 mmol·kg-1磷酸盐,同时加入10mmol·kg-1硝酸钙或5 mmol·kg-1氯化钾,在15%或30%的含水率下培养40 d,之后种植黑麦草.结果表明,与单独施用磷酸盐相比,采用磷酸盐与钙、氯结合或增加培养期间的土壤含水率后,土壤DTPA-Pb含量下降3.92%~26.1%;对于同一添加剂处理,培养期间土壤含水率从15%增加到30%,土壤有效铅(DTPA-Pb)含量下降8.83%~24.4%.增加土壤含水率后,土壤有效磷(Olsen-P)含量均显著升高(p0.05).土壤铅的EXAFS分析表明,与未施用磷酸盐的对照相比,土壤中加入磷酸盐后矿物态铅的比例由57%上升至81%,加施钙、氯或增加土壤含水率后,多数处理矿物态铅的比例有所下降,而有机结合态铅比例上升.与对照相比,污染土壤中施用磷酸盐后,植物产量大幅增加,但施用钙、氯或增加培养期间含水率后,部分处理植物产量有所下降.以上结果表明,在铅冶炼污染土壤中加入磷酸盐时,加入钙、氯或者增加土壤含水率均有利于铅的稳定,但以上措施可能对植物生长产生不利影响.     

覆膜与降雨类型对土壤水分及NO3--N淋失的影响

在丹江口库区青塘河五龙池小流域,以黄棕壤横垄种植玉米为例,设置覆膜与无覆膜两种处理,采用田间小区实验研究覆膜与降雨类型对0~30 cm土壤水分和NO-3-N淋失的影响.结果表明:两处理土壤含水量均随土层加深而增加,与无覆膜相比覆膜可降低0~10、10~20、20~30cm土层中的含水量.不同降雨类型对覆膜土壤含水量的影响有区别,小雨时3层土壤间差异显著,含水量随土层加深急剧增加;中雨时10~20cm比0~10 cm、20~30 cm比10~20 cm分别高50.80%、6.62%,0~10 cm土壤含水量显著低于10~20 cm和20~30 cm;暴雨时含水量随土层加深增幅变小;覆膜土壤土层越深土壤含水量受降雨的影响越小.覆膜可降低0~10、10~20 cm土层中的NO-3-N淋失量,分别降低40.74%、24.48%,但会增加20~30 cm的淋失;两处理土壤NO-3-N淋失量均随土层加深而增加.不同降雨类型对覆膜土壤NO-3-N淋失的影响也有区别,小雨时随土壤深度的增加淋失量增多;中雨时,0~10、20~30 cm NO-3-N淋失量分别为10~20 cm的1.75、8.41倍;暴雨时,0~10、20~30 cm分别比10~20 cm低18.97%和60.69%.土壤中NO-3-N淋失受土壤含水量的影响,且随土层加深含水量对NO-3-N淋失的影响减弱.     

交联壳聚糖对铀的吸附研究

以壳聚糖(CTS)为原料,在碱性条件下用环氧氯丙烷对壳聚糖进行化学改性,制得不溶水的交联壳聚糖(CCTS)。利用CCTS吸附铀(UO22+),探讨吸附动力学规律以及初始浓度,pH值的影响。实验结果表明,CCTS对UO22+的吸附符合Langmu ir吸附等温模型,并能用准二级速率方程对吸附动力学加以描述。当在CCTS为10 mg,pH为3,UO22+初始浓度为50μg/mL条件下,CCTS对UO22+的吸附去除率为98%以上。     

马拉硫磷及其水解产物对圆瘤浮萍的生长抑制及氧化损伤作用

为了探讨马拉硫磷和主要水解产物对圆瘤浮萍的生长抑制作用及可能的氧化损伤机制,采用静态培养法,研究不同浓度的马拉硫磷及其水解产物二甲基二硫代磷酸酯(DMDTP)、二甲基硫代磷酸酯(DMTP)、二甲基磷酸酯(DMP)对圆瘤浮萍生长、叶绿素含量、叶绿体活性、超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性及丙二醛(MDA)含量的影响。结果表明,暴露7 d后,浓度为100 mg a.i.·L-1处理下的浮萍叶状体生长量与空白对照组无显著性差异;DMDTP、DMTP和DMP对圆瘤浮萍叶状体生长量的半数抑制浓度(7 d-IC50)分别为52.9、45.5和98.0 mg a.i.·L-1。随着试验液中DMDTP、DMTP和DMP浓度的升高,圆瘤浮萍叶绿素含量均明显降低,叶绿体活性则分别表现为诱导-抑制、抑制和抑制效应。在DMDTP、DMTP和DMP胁迫下,脂质过氧化产物丙二醛(MDA)含量明显增加;圆瘤浮萍体内的抗氧化酶系统均受到影响。总体表现为随着DMDTP浓度的增加,SOD活性先降低后升高;DMTP和DMP胁迫下,SOD活性呈现先降后升再降的趋势;POD和CAT活性则随3种水解产物浓度的增加呈现先升后降趋势;这表明抗氧化酶系统对外部胁迫的应答很复杂。马拉硫磷对圆瘤浮萍的毒性较小,其水解产物DMDTP、DMTP和DMP均对圆瘤浮萍的生长产生一定的毒性作用。在实际生产中,应多加关注马拉硫磷水解产物对环境生物的风险评估。     

Americium,plutonium and uranium contamination and speciation in well waters,streams and atomic lakes in the Sarzhal region of the Semipalatinsk Nuclear Test Site,Kazakhstan

New data are reported on the concentrations, isotopic composition and speciation of americium, plutonium and uranium in surface and ground waters in the Sarzhal region of the Semipalatinsk Test Site, and an adjacent area including the settlement of Sarzhal. The data relate to filtered water and suspended particulate from (a) streams originating in the Degelen Mountains, (b) the Tel′kem 1 and Tel′kem 2 atomic craters, and (c) wells on farms located within the study area and at Sarzhal. The measurements show that ²⁴¹Am, ^239,240Pu and ²³⁸U concentrations in well waters within the study area are in the range 0.04–87 mBq dm⁻³, 0.7–99 mBq dm⁻³, and 74–213 mBq dm⁻³, respectively, and for ²⁴¹Am and ^239,240Pu are elevated above the levels expected solely on the basis of global fallout. Concentrations in streams sourced in the Degelen Mountains are similar, while concentrations in the two water-filled atomic craters are somewhat higher. Suspended particulate concentrations in well waters vary considerably, though median values are very low, at 0.01 mBq dm⁻³, 0.08 mBq dm⁻³ and 0.32 mBq dm⁻³ for ²⁴¹Am, ^239,240Pu and ²³⁸U, respectively. The ²³⁵U/²³⁸U isotopic ratio in almost all well and stream waters is slightly elevated above the ‘best estimate’ value for natural uranium worldwide, suggesting that some of the uranium in these waters is of test-site provenance. Redox analysis shows that on average most of the plutonium present in the microfiltered fraction of these waters is in a chemically reduced form (mean 69%; 95% confidence interval 53–85%). In the case of the atomic craters, the proportion is even higher. As expected, all of the americium present appears to be in a reduced form. Calculations suggest that annual committed effective doses to individual adults arising from the daily ingestion of these well waters are in the range 11–42 μSv (mean 21 μSv). Presently, the ground water feeding these wells would not appear to be contaminated with radioactivity from past underground testing in the Degelen Mountains or from the Tel′kem explosions.     

Appraisal of measurement methods, chemical composition and sources of fine atmospheric particles over six different areas of Northern Belgium

Daily and seasonal variation in the total elemental, organic carbon (OC) and elemental carbon (EC) content and mass of PM_2.5 were studied at industrial, urban, suburban and agricultural/rural areas. Continuous (optical Dustscan, standard tapered element oscillating micro-balance (TEOM), TEOM with filter dynamics measurement system), semi-continuous (Partisol filter-sampling) and non-continuous (Dekati-impactor sampling and gravimetry) methods of PM_2.5 mass monitoring were critically evaluated. The average elemental fraction accounted for 2-6% of the PM_2.5 mass measured by gravimetry. Metals, like K, Mn, Fe, Cu, Zn and Pb were strongly inter-correlated, also frequently with non-metallic elements (P, S, Cl and/or Br) and EC/OC. A high OC/EC ratio (2-9) was generally observed. The total carbon content of PM_2.5 ranged between 3 and 77% (averages: 12-32%), peaking near industrial/heavy trafficked sites. Principal component analysis identified heavy oil burning, ferrous/non-ferrous industry and vehicular emissions as the main sources of metal pollution.     

Facilitating substance phase‐out through material information systems and improving environmental impacts in the recycling stage of a product

The amount of electrical and electronic products is increasing rapidly, and this inevitably leads to the generation of large quantities of waste from these goods. Some of the generated e‐waste ends up in regions with sub‐standard recycling systems and may be processed under poor conditions. During uncontrolled incineration, halogenated dioxins and furans can be generated from brominated and chlorinated compounds in the products. In order to reduce the health and environmental risks involved in the recycling stage of the life cycle of electronics, an effective design‐for‐environment process must be established during the product development phase. Knowledge of the chemical substances in the product is crucial to being able to make informed decisions. Through full knowledge of the material content of procured components, phase‐outs of unwanted substances, such as halogenated substances, can be performed in an effective manner. Therefore, information is the key to success in phasing‐out substances; facilitating compliance of legal provisions for manufacturers of electrical and electronic devices; and improving the environmental footprint of products as they reach the end of the life cycle. After an introduction to the challenges of electronics waste management, this paper describes supply chain information systems and how they are used to facilitate substance phase‐outs in the electronics industry. Sony Ericsson has been working with phase‐outs of unwanted substances since it was founded in 2001. Through the introduction of a material declaration system that keeps track of all substances in the components used in the company's products, Sony Ericsson has been able to replace unwanted substances to improve environmental impacts at the recycling stage of a product.     

EFFECT OF SOIL STERILIZATION BY MERCURIC CHLORIDE ON HERBICIDE SORPTION BY SOIL

Microbial inhibitors such as mercuric chloride are frequently used to sterilize soil or soil–water slurries in experimental studies on the fate of xenobiotics in the environment. This study examined the influence of mercuric chloride additions to soil–water slurries on the sorptive behaviour of a phenoxy herbicide (2,4-D) in soil. The results demonstrated that mercuric chloride strongly decreased the capacity of the soil to retain herbicides, and that the interference of mercuric chloride with herbicide sorption increased with increasing soil organic carbon contents. Because of the competitive sorption between mercuric chloride and the phenoxy herbicide, we conclude that mercuric chloride may not be a good soil sterilization procedure for use in xenobiotic fate studies.     

艾比湖水体中氯离子测定方法分析

用氯离子选择电极法测定艾比湖水体中氯离子的含量,对测定条件进行了探讨。结果表明,标准曲线在1.0×10-1~1.0×10-4mol/L内呈良好的线性关系,回收率为96.4%~103%,RSD为3.41%~4.34%,该方法简便、快速、准确,在实际工作中应用效果较为满意。     

2,4-D mineralization in unsaturated and near-saturated surface soils of an undulating,cultivated Canadian prairie landscape

The herbicide 2,4-D [2,4-(dichlorophenoxy) acetic acid] is one of the most widely used pesticides in the Canadian prairies and is frequently detected as a ground and surface water contaminant. The objective of this paper was to determine the magnitude and extent of variation of 2,4-D mineralization in a cultivated undulating prairie landscape. Microcosm incubation experiments, using a 4 × 3 × 2 factorial experimental design (soil moisture, 4 levels: 60, 85, 110, 135% of field capacity; slope position, 3 levels: upper-, mid- and lower-slopes; soil depth, 2 levels: 0–5 and 5–15 cm), were used to assess 2,4-D mineralization. The first-order mineralization rate constant (k₁) varied from 0.03 to 0.22 day^{? 1}, while total 2,4-D mineralization varied from 31 to 52%. At near-saturated conditions (110 and 135% of field capacity), the onset of 2,4-D degradation was delayed in soil obtained from the upper- and mid-slopes but not in soils obtained from the lower-slope position. The k₁ and total 2,4-D mineralizationwas significantly influenced by all three factors and their interactions. The Freundlich sorption coefficient of 2,4-D ranged from 0.83 to 2.46 ug ^1–1/ng^{? 1} mL^1/n and was significantly influenced by variations in soil organic carbon content across slope positions. The infield variability of 2,4-D sorption and mineralization observed across slope positions in this undulating field was comparable in magnitude and extent to the regional variability of 2,4-D sorption and mineralization observed in surface soils across Manitoba. The large variability of 2,4-D mineralization and sorption at different slope positions in this cultivated undulating field suggests that landform segmentation models, which are used to delineate slope positions, are important considerations in pesticide fate studies.