红外法测定土壤中石油烃的改进研究

通过气相色谱-质谱法定性解析红外法测定土壤中石油烃的各前处理阶段萃取物组分变化情况,探讨了用石油醚萃取土壤中石油烃空白高的原因,发现采用二氯甲烷为萃取剂,空白值低且精密度提高.     

化工厂场地酸化土壤工程化中和修复案例研究

对江苏某化工厂酸化地块进行了氧化钙中和修复工程研究。Ⅰ、Ⅱ、Ⅲ号地块剖面混合土样pH值分别为3.56、4.68和4.74,土壤修复目标定在pH值为6~8基本近中性。通过室内试验确定Ⅰ、Ⅱ、Ⅲ号地块土壤生石灰掺混比例为0.5%、0.3%和0.3%;现场中试后Ⅰ、Ⅱ、Ⅲ号地块石灰掺混比例调整为0.7%、0.35%和0.3%;中试结果用于场地机械搅拌工程修复,修复过程中定期随机采样对中和效果进行连续监测。监测结果基本达标后请第三方对修复效果进行评估,最后土壤回填压实。修复结果表明借助于科学的石灰添加量和工程机械混合措施,能快速有效地修复酸化地块土壤。     

面向污染场地的环境修复功能材料

在回顾环境功能材料研究进展的基础上,将材料按功效分为固化/稳定化材料、氧化还原剂类材料以及催化剂类材料,重点对固化/稳定化材料进行了介绍。根据环境材料科学的发展前沿提出了污染场地环境修复功能材料的发展趋势,并总结了功能材料开发与应用中的一些问题。     

重金属污染土壤及场地的植物修复技术发展与应用

重金属污染土壤及场地的治理工作迫在眉睫,植物修复技术以其成本低、不破坏土壤生态环境、无二次污染、易被公众接受等优点,受到了学术界的广泛关注.近年来,国内外在植物修复技术的植物资源筛选、调控技术、修复植物产后处理等方面进行了广泛的研究.植物修复已经从实验室阶段走向了田间示范和推广应用阶段.现就近年来植物修复技术在重金属污...     

石墨炉原子吸收光谱法测定土壤中痕量钻

建立了硝酸－氢氟酸－盐酸混酸体系微波消解土壤样品,石墨炉原子吸收分光光谱法测定土壤中痕量钴的方法。通过对标准土样的测定结果表明,该方法容易操作、准确、可靠。     

New best estimates for radionuclide solid–liquid distribution coefficients in soils. Part 2. Naturally occurring radionuclides

Predicting the transfer of radionuclides in the environment for normal release, accidental, disposal or remediation scenarios in order to assess exposure requires the availability of an important number of generic parameter values. One of the key parameters in environmental assessment is the solid liquid distribution coefficient, K_d, which is used to predict radionuclide–soil interaction and subsequent radionuclide transport in the soil column. This article presents a review of K_d values for uranium, radium, lead, polonium and thorium based on an extensive literature survey, including recent publications. The K_d estimates were presented per soil groups defined by their texture and organic matter content (Sand, Loam, Clay and Organic), although the texture class seemed not to significantly affect K_d. Where relevant, other K_d classification systems are proposed and correlations with soil parameters are highlighted. The K_d values obtained in this compilation are compared with earlier review data.     

Combined use of GIS and environmental indicators for assessment of chemical, physical and biological soil degradation in a Spanish Mediterranean region

Soil is one of the main non-renewable natural resources in the world. In the Valencian Community (Mediterranean coast of Spain), it is especially important because agriculture and forest biomass exploitation are two of the main economic activities in the region. More than 44% of the total area is under agriculture and 52% is forested. The frequently arid or semi-arid climate with rainfall concentrated in few events, usually in the autumn and spring, scarcity of vegetation cover, and eroded and shallow soils in several areas lead to soil degradation processes. These processes, mainly water erosion and salinization, can be intense in many locations within the Valencian Community. Evaluation of soil degradation on a regional scale is important because degradation is incompatible with sustainable development. Policy makers involved in land use planning require tools to evaluate soil degradation so they can go on to develop measures aimed at protecting and conserving soils. In this study, a methodology to evaluate physical, chemical and biological soil degradation in a GIS-based approach was developed for the Valencian Community on a 1/200,000 scale. The information used in this study was obtained from two different sources: (i) a soil survey with more than 850 soil profiles sampled within the Valencian Community, and (ii) the environmental information implemented in the Geo-scientific map of the Valencian Community digitised on an Arc/Info GIS. Maps of physical, chemical and biological soil degradation in the Valencian Community on a 1/200,000 scale were obtained using the methodology devised. These maps can be used to make a cost-effective evaluation of soil degradation on a regional scale. Around 29% of the area corresponding to the Valencian Community is affected by high to very high physical soil degradation, 36% by high to very high biological degradation, and 6% by high to very high chemical degradation. It is, therefore, necessary to draw up legislation and to establish the policy framework for actions focused on preventing soil degradation and conserving its productive potential.     

Oxidation of antimony (III) in soil by manganese (IV) oxide using X-ray absorption fine structure

The oxidation of antimony (III) in soils was studied using X-ray absorption fine structure (XAFS) spectra. An andosol soil sample and artificial soil samples (SiO₂ blended with iron (III) hydroxide and manganese (IV) oxide) were used herein. After adding antimony (III) oxide to all soil samples, the oxidation process was observed by recording the XAFS spectra of Sb K-edge, Fe K-edge, and Mn K-edge. The results indicated that manganese (IV) oxide played an important role in the oxidation of Sb(III); however iron (III) hydroxide was not directly related to the reaction. During a 2-hr continuous Sb K-edge X-ray absorption near edge structure (XANES) measurement with an interval of 1 min of one of the artificial soil samples (SiO₂ + MnO₂ + Sb₂O₃), a pseudo-first-order reaction was determined with an average estimated rate of 0.52 ± 0.04 hr^? 1. Compared to the lower oxidation rate of andosol, it is suggested that because of the low concentration of Mn(IV) in natural soils, the oxidation process of Sb(III) might be relatively slow and require more time to convert Sb(III) to Sb(V).     

Natural and anthropogenic contamination of the Fratta-Gorzone river (Veneto, Italy)

Stream-bed sediment samples were collected in 2001 and 2004 along the Fratta-Gorzone River (Italy) to assess the level of heavy metal contamination. The river stretch most affected by discharges of tannery effluent showed total and pseudo-total Cr levels (up to 2,860 mg/kg) that greatly exceed national and international chemical sediment quality standards. The most contaminated section of the river bed is located downstream of the main industrial discharge. However, a large fraction of the Cr present in the sediment appears to be of lithogenic origin. At most sites, more than 50% of Cr is not soluble in aqua-regia and thus unlikely to be very mobile or easily bio-available. A negligible risk to the benthic community can be inferred for Pb, Zn, Cd, Cu and Ni. This work highlights the limitation of using existing chemical sediment quality standards alone for risk assessment. The collection and analysis of suspended solids, the determination of river discharge and of dissolved Cr at 10 field stations allowed to estimate the particulate and dissolved Cr load and to locate the river stretch that was the likely source of contaminated sediment. The pumping of dilution water from the Adige River into the Fratta-Gorzone River did not produce the expected contaminant dilution effect due to re-suspension of contaminated solid particles and the release of Cr in solution.     

Predicted effects of prescribed burning and harvesting on forest recovery and sustainability in southwest Georgia, USA

A model-based analysis of the effect of prescribed burning and forest thinning or clear-cutting on stand recovery and sustainability was conducted at Fort Benning, GA, in the southeastern USA. Two experiments were performed with the model. In the first experiment, forest recovery from degraded soils was predicted for 100 years with or without prescribed burning. In the second experiment simulations began with 100 years of predicted stand growth, then forest sustainability was predicted for an additional 100 years under different combinations of prescribed burning and forest harvesting. Three levels of fire intensity (low, medium, and high), that corresponded to 17%, 33%, and 50% consumption of the forest floor C stock by fire, were evaluated at 1-, 2-, and 3-year fire return intervals. Relative to the control (no fire), prescribed burning with a 2- or 3-year return interval caused only a small reduction in predicted steady state soil C stocks (< or =25%) and had no effect on steady state tree wood biomass, regardless of fire intensity. Annual high intensity burns did adversely impact forest recovery and sustainability (after harvesting) on less sandy soils, but not on more sandy soils that had greater N availability. Higher intensity and frequency of ground fires increased the chance that tree biomass would not return to pre-harvest levels. Soil N limitation was indicated as the cause of unsustainable forests when prescribed burns were too frequent or too intense to permit stand recovery.