铬污染土壤修复技术研究进展

指出了土壤铬污染问题日益严重,铬污染土壤的修复成为当今的研究热点.对土壤铬污染特征及危害、铬污染土壤的修复技术、机理及应用进行了综述,分析了不同物理、化学、生物修复技术的优劣势,提出了在未来铬污染的修复中,综合考虑土壤适用类型、修复周期、铬污染浓度、经济成本等因素来选择合适的修复方案.并建议选用实地污染土壤为研究对象,...     

铬污染场地修复技术研究概况

指出了随着我国工业化进程的不断加快,工业污染给环境造成极大破坏,尤其重金属污染不仅引起了我国环保部门的高度重视,而且已成为全球关注的热点.铬(Cr)因具有致癌、高毒性特点,给土壤造成的污染在重金属污染中尤为严重,加强对铬污染的治理是一件利国利民的大事,无论是环保部门还是相关生产企业都应将铬污染治理当做工作中的重点.考虑到我国铬污染场地比较多,而且治理形式严峻,因此,需要对铬污染场地修复技术进行一定的研究.鉴于此,分析Cr的存在形态及当前Cr污染现状,以此为基础提出了Cr污染场地修复技术,为有效降低Cr污染提供参考.     

高压旋喷注射法在城市石油烃污染场地修复中的实践应用

指出了土壤的石油烃污染问题已成为全球面临的重要环境问题之一,在分析土壤石油烃污染危害的基础上,介绍了目前修复石油烃污染土壤的技术,包括物理修复、生物修复和化学修复等,并对各种技术的修复原理、优缺点及适用范围进行了综述。其中,原位化学氧化技术是修复城市保留建筑内的石油烃污染场地有效的技术之一,以上海市的工程实例对高压旋喷注射法在城市石油烃污染场地的原位修复过程中的应用情况进行了论证。     

有机物-重金属复合污染土壤的治理

有机物-重金属复合污染土壤现阶段已经成为一种普遍的土壤污染形式,由于污染物质之间的相互作用,使得复合污染土壤的处理难度增大,在前人研究的基础上总结了有机物污染场地、重金属污染场地,以及有机物重金属复合污染场地修复技术的研究现状,提出了植物-微生物联合修复、电动-氧化修复和热脱附-土壤淋洗技术是修复复合污染土壤的有效途径,为进一步开发新型协同处理技术提供参考,对复合污染土壤的修复有积极意义。     

污染场地调查评估现状及市场分析

指出了我国正处于工业化和城市化迅猛发展的时期,污染场地所引发的环境损害和民事纠纷等受到广泛关注,污染场地土壤与地下水的修复治理刻不容缓。分析了我国污染场地修复的现状与存在的问题:我国污染场地修复起步较晚,相应的管理体系尚未完全建立,导致当前污染场地的调查与修复存在相关法律法规和标准不完善、场地修复资金落实困难、污染场地修复技术工程应用经验不足、场地资料整合困难等。在我国污染场地修复产业发展潜力巨大的背景下,提出了只有深刻认识到问题现状并建立规范的市场秩序才能更好地推动土壤修复产业的健康发展。     

工业用地土壤铬污染现状及修复技术概述

以工业用地铬(Cr)污染为背景,阐述了铬(Cr)的地球环境化学行为特征。介绍了固化/稳定化、淋洗技术、生物修复技术和电动修复技术这4种适合于工业铬污染用地的修复技术,分析了其优缺点和使用范围,供相关人员进行参考。     

焦化类污染场地氧化降解多环芳烃试验研究

随着我国城市化进程的加快,工业场地中高浓度残留的多环芳烃污染已成为研究者亟待解决的难题。选取我国山西某典型焦化类污染场地,筛选化学氧化技术对场地污染土壤进行修复。为研究不同的化学氧化药剂对本工程多环芳烃污染土壤的修复效果,为后期工程实施提供技术支持,启动化学氧化修复试验。试验样品来自于现场两个不同地点,土壤中6种目标污染物总浓度分别高达24.43 mg/kg、74.96 mg/kg。试验分别研究了两种化学氧化药剂K药剂(主要成分为过硫酸钠和硫酸亚铁)及S药剂(主要成分为过氧化氢和硫酸亚铁)对轻度和重度污染土壤修复的效果,并结合工程修复目标值、现场土质特点等情况,确定采用S药剂修复本场地PAHs和TPH污染土壤,建议工程药剂投加比为2%且分批次投加。结果表明:化学氧化修复技术具有去除效率高的特点,非常适合我国焦化类场地污染土壤的修复;试验除为山西某焦化类污染场地提供技术外,对其它场地多环芳烃和石油烃污染土壤的化学氧化修复也具有非常好的参考价值。     

多环芳烃污染土壤化学氧化修复及案例研究

以某化工厂场地PAHs污染土壤化学氧化修复工程为例。综述了多环芳烃(PAHs)污染土壤化学氧化修复技术,根据场地污染情况,将污染土壤分为中度及轻度污染土壤,通过现场中试确定活化过硫酸盐作为工程的修复药剂。现场施工中,采用筛分混合设备对土壤进行修复施工,修复后进行暂存养护。养护完成后,由第三方检测机构进行了取样检测,并评估了修复效果。结果表明:工程土壤中PAHs总体达到修复目标值,修复达标。     

重金属污染土壤生态修复研究

阐述了土壤重金属污染的修复,在此基础上分析了土壤重金属污染修复的必要性,就重金属土壤生态修复技术从物理工程、物化修复以及生物修复三方面进行了重点研究。     

土壤污染修复技术研究综述

介绍了土壤重金属污染、有机物污染采用生物修复、植物修复、光化学修复、利用城市固体废弃物修复等技术。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.