Response of macrozoobenthos communities to ecological engineering remediation in a hypertrophic urban lake

The relationship of macrozoobenthos communities with some environmental variables, and their response to the ongoing restoration measures were studied in a small hypertrophic urban lake near the Yangzte River, China. Twenty taxa including 9 oligochaetes, 7 insects, 2 mollusks and two other animals were found during March 2005 to May 2006. The reappearance of some indigenous macrozoobenthos species showed that the ecological engineering remediation carried out was helpful for the recovery of the macrozoobenthos communities. Through canonical correspondence analysis (CCA), it was detected that temperature (T), conductivity (COND), Secchi depth/deep (SD/Deep), TN, total suspended solids (SS) and chemical oxygen demand (CODcr) were significant environmental factors that influenced the pattern of macrozoobenthos. Limnodrilus hoffmeisteri, Tanypus sp. and Alocinma longicornis could be used as potential bio-indicators in monitoring the development of ecological restoration.

Remediation of Persistent Organic Pollutants (POPs) in Two Different Soils

Persistent organic pollutants (POPs) are a set of chemicals that are toxic, persist in the environment for long periods of time, and biomagnify as they move up through the food chain. The most widely used method of POP destruction is incineration, which is expensive and could result in undesirable by-products. An alternative bioremediation technology, which is cheaper and environ-mentally friendly, was tested during this experiment. Two different soil types containing high and low organic matter (OM) were spiked with 100 mg/kg each of pyrene and Aroclor 1248 and planted with three different species of grasses. The objective of the study was to determine residue recovery levels (availability) and potential effectiveness of these plant species for the remediation of POPs. The results showed that recovery levels were highly dependent on the soil organic matter content—very low in all treatments with the high OM content soil compared to recoveries in the low OM soil. This indicates that availability, and, hence, biodegradability of the contaminants is dependent on the organic matter content of the soil. Moreover, the degree of availability was also significantly different for the two classes of chemicals. The polyaromatic hydrocarbon (PAH) recovery (availability) was extremely low in the high organic matter content soil compared to that of the polychlorinated biphenyls (PCBs). In both soil types, all of the plant species treatments showed significantly greater PCB biodegradation compared to the unplanted controls. Planting did not have any significant effect on the transformation of the PAHs in both soil types; however, planting with switchgrass was the best remedial option for both soil types contaminated with PCB.

植物克隆性在生态修复中的意义：鄂尔多斯高原赖草和沙鞭的案例

克隆植物通过克隆生长能够很好的适应异质性的生境。在进行植被修复的研究和实践中，注意发扬或引进具有重要资源价值的克隆植物是重要的恢复生态学思考和途径。本文主要应用实验生态学的方法，通过对鄂尔多斯高原不同克隆植物克隆性及其对水分条件的反应的比较，以及对不同克隆植物抵抗风蚀和风蚀坑修复的能力的比较，探讨克隆植物对干旱(水分条件)及风蚀的适应机制，从而对克隆植物的克隆性在生态修复中的意义进行了研究和阐述。 　　对不同水分条件下赖草(Leymus secalinus (Georgi.) Tzvel)和沙鞭(Psammochloa villosa (Trin.) Bor)克隆性的研究表明：克隆生长开始时间和克隆生长率二者与克隆植物新产生子代分株数量之间存在着显著的相关关系，说明克隆生长开始时间和克隆生长率能够作为准确评价克隆性的指标;相对于沙鞭来说，赖草具有更强的克隆性，表现在它的早的克隆生长开始时间、高的克隆生长率，并且这种差异可以被水分条件所修饰;植物的克隆性对水分条件具有较强的可塑性，这种可塑性具有种间差异。相对赖草来说，沙鞭能更好地适应干旱条件。 　　克隆植物植株有两种繁殖体类型，分株和种子。本研究对分别从分株来源和种子来源的赖草与沙鞭植株在不同水分条件下生长状况及克隆性进行了比较，结果表明：水分的增加，有利于赖草的生长;而对于沙鞭来说，水分抑制了分株来源的沙鞭植株的生长，但对种子来源的沙鞭植株的生长有着促进作用。克隆植物的克隆性在水分条件较好的情况下能够得到更好的表达。不同来源有赖草植株之间克隆性没有明显差异;对于沙鞭来说，分株来源的沙鞭植株克隆性受水分条件的影响不明显，但水分有利于种子来源的沙鞭植株克隆性的表达。说明不同繁殖体类型来源的植株，克隆性对水分的反应格局存在着一定的差异。分株来源的沙鞭植株对干旱条件具有比种子来源的植株更强的适应性。 　　通过对沙鞭和赖草实生幼苗在不同风蚀程度下生长状况的比较，结果表明二者幼苗在抵抗风蚀时采取不同的策略。风蚀显著降低了赖草产生新生分株的能力，而对沙鞭潜在分株数没有显著影响。赖草实生幼苗生长状况在轻中度风蚀条件下与对照处理没有显著差异，说明对风蚀具有较强的抵抗能力，其策略可能是风险分担，赖草具有的强克隆性使之能快速产生新的子代分株，从而分担了风蚀造成的风险;沙鞭实生幼苗的生长状况受风蚀影响较为明显，但风蚀没有能对其产生潜在分株(芽)的能力产生显著的影响，说明沙鞭实生幼苗对风蚀可能采取的是通过芽的产生贮存资源、逃避风险、等待机会的策略。赖草和沙鞭对风蚀所采用的不同适应策略，可能会影响到二者在自然条件下种群更新方式的选择。 　　为了探讨克隆植物对风蚀坑修复能力及机理，研究了沙鞭和赖草对种群内风蚀坑的修复过程，结果表明：合轴型克隆草本赖草具有比单轴型克隆草本沙鞭更强的植被修复能力，能够在风蚀坑中产生更多的新生分株，这主要归功于赖草的强克隆性，而赖草间隔子的可塑性反应也有利于将更多的新生分株放置在风蚀坑内。二者进行植被修复的机理有所差异，赖草对风蚀坑的修复主要是通过周围根茎扩展进入坑中，然后产生新的分株;而沙鞭不仅可以通过周边根茎进入产生新的分株，同时也可以通过刺激深层休眠芽来产生新的分株。二者都能在风蚀坑中产生比自然条件下更多的分株，以更好利用风蚀坑中充足的光照;但同时这些分株的生长也受到风蚀坑中养分条件的制约，生物量和生长状况都不如自然条件下形成的分株。 　　 　　

CHARACTERISTICS OF FATTY ACID METHYL ESTERS (FAMEs) AND ENZYMATIC ACTIVITIES IN SEDIMENTS OF TWO EUTROPHIC LAKES

Enzymatic activities and fatty acid methyl esters (FAMEs) in the sediments of two eutrophic lakes in Wuhan city were investigated. The results showed phosphatase and dehydrogenase activities in the lotus zone and plant floating bed zone were significantly lower than those in other sites, and urease activity was the highest where microorganism agents were put in. Fatty acid group compositions indicated the predominance of aerobic bacteria in the surface sediments in shallow lakes. The ratios of FAMEs specific for bacteria and Gram-positive bacteria exibited significant differences between the two lakes. The results of trans to cis indicated that the microorganisms in Lake Yuehu could adapt themselves to environmental stress better. The enzymatic activities and FAMEs showed differences in different sites, indicating that ecological restoration measures and environmental conditions could affect lake sediment to some extent. But the monitoring, work would be done in series to exactly evaluate the effect of the remediation measures.

EXPERIMENTS ON AQUATIC ECOSYSTEM REGIME SHIFT IN ENCLOSURES NEAR LAKE DIANCHI, CHINA

To discover how a lake converts from a turbid state to clean state, and what drives this process, we constructed controlled enclosure ecosystems and used the ecological remediation method to force ecosystems to convert from the turbid state to the clean state. Our results show that the driving forces include temperature., macrophyte, silver carp and mussel, which form a combined force to drive the controlled ecosystem to switch. There is a threshold existing in treated enclosure ecosystem during the conversion from turbid to clean state. When TP <0.09 mg.L-1, Chl-a <0.036 mg.L-1, transparency >62 cm, TN <2.15 mg.L-1, CODMn <13.7 mg.L-1, tubidity <10, and the number of algal cells <10(6) cells.L-1, the treated ecosystem changes sharply from turbid to clean state. The conversion process can be divided into three phases: turbid state, clean-turbid transitional state as well as clean state, and described with the power function Y = a*X-b (where Y is water parameter, X is time, a and b are constants), which indicates that the shift in the enclosure ecosystem from turbid to clean state is discontinuous.

Phytoremediation of triazophos by Canna indica Linn. in a hydroponic system

The phytoremediation of triazophos (O, O-diethyl-O-(1-phenyl-1, 2, 4-triazole-3-base) sulfur phosphate, TAP) by Canna indica Linn. in a hydroponic system was studied. After 21 d of exposure, the removal kinetic constant (K) of TAP was 0.0229-0.0339 d(-1) and the removal percentage of TAP was 41-55% in the plant system and the K and removal percentage of TAP were about 0.002 d(-1) and 1%, respectively, in darkness and disinfected control. However, the K and removal percentage of TAP were 0.006 d(-1) and approximately 11%, respectively, in the treatment with eluate from the media of constructed wetland. The contribution of plant to the remediation of TAP was 74% and C. indica played the most important role in the hydroponic system. Under the stress of TAP and without inorganic phosphorus nutrient, the activity of phosphatase in the plant system increased and phytodegradation was observed. The production and release of phosphatase is seen as the key mechanism for C. indica to degrade TAP. C. indica, which showed the potential of phytoremediation of TAP, and is commonly used in constructed wetland, so the technique of phytoremediation of TAP from contaminated water can be developed with the combination of constructed wetland.

Man-made desert algal crusts as affected by environmental factors in Inner Mongolia, China

Man-made desert algal crusts were constructed on a large scale (3000m(2)) in Inner Mongolia, China. Microcoleus vaginatus was mass cultivated and inoculated directly onto unconsolidated sand dune and irrigated by automatic sprinkling micro-irrigation facilities. The crusts were formed in a short time and could resist the erosion of winds and rainfalls 22 days after inoculation. The maximum biomass in the man-made algal crusts could also reach 35 mu g Chl a/cm(2) of soil. Effects of environmental factors such as temperature, irrigation, rainfall and soil nutrients on algal biomass of man-made algal crusts were also studied. It was found that rainfalls and lower light intensity had significantly positive effects on the biomass of man-made algal crusts. The preliminary results suggested that man-made algal crusts could be formed rapidly, and thus it might be a new feasible alternative method for fixing unconsolidated sand. (c) 2006 Elsevier Ltd. All rights reserved.

Effects of heavy metals on plants and resistance mechanisms

Goal, Scope and Background. As one of the consequences of heavy metal pollution in soil, water and air, plants are contaminated by heavy metals in some parts of China. To understand the effects of heavy metals upon plants and the resistance mechanisms, would make it possible to use plants for cleaning and remediating heavy metal-polluted sites. Methods. The research results on the effects of heavy metals on plants and resistant mechanisms are compiled from Chinese publications from scientific journals and university journals, mostly published during the last decade. Results and Discussion. Effects of heavy metals on plants result in growth inhibition, structure damage, a decline of physiological and biochemical activities as well as of the function of plants. The effects and bioavailability of heavy metals depend on many factors, such as environmental conditions, pH, species of element, organic substances of the media and fertilization, plant species. But, there are also studies on plant resistance mechanisms to protect plants against the toxic effects of heavy metals such as combining heavy metals by proteins and expressing of detoxifying enzyme and nucleic acid, these mechanisms are integrated to protect the plants against injury by heavy metals. Conclusions. There are two aspects on the interaction of plants and heavy metals. On one hand, heavy metals show negative effects on plants. On the other hand, plants have their own resistance mechanisms against toxic effects and for detoxifying heavy metal pollution. Recommendations and Outlook. To study the effects of heavy metals on plants and mechanisms of resistance, one must select crop cultivars and/or plants for removing heavy metals from soil and water. More highly resistant plants can be selected especially for a remediation of the pollution site. The molecular mechanisms of resistance of plants to heavy metals should be studied further to develop the actual resistance of these plants to heavy metals. Understanding the bioavailability of heavy metals is advantageous for plant cultivation and phytoremediation. Decrease in the bioavailability to farmlands would reduce the accumulation of heavy metals in food. Alternatively, one could increase the bioavailability of plants to extract more heavy metals.

铬污染土壤修复过程中土壤细菌群落多样性的RFLP分析

对污染土壤修复过程中土壤细菌群落多样性的变化进行研究。【方法】以淹水培养后的模拟铬污染土壤为供试材料,通过直接提取土壤中总细菌DNA,利用细菌专一引物克隆细菌16S rDNA片段,分别建立克隆文库。利用PCR-RFLP技术,分析比较了土壤淹水10 d(对照,S1)、添加Cr(Ⅵ)淹水10 d(S2)、添加Cr(Ⅵ)和Fe(OH)3淹水10 d(S3)及20 d(S4)4个处理中土壤细菌群落的变化。【结果】用专一引物克隆细菌16S rDNA片段,分别建立了克隆文库;用限制性内切酶RsaⅠ进行细菌16S rDNA PCR-RFLP分析,分别得到123,120,97和69个酶切类型,库容值分别为54.92%,55.43%,65.33%和76.60%;Shannon-Wiener指数、Gini指数、物种丰富度指数(dMa)和物种均匀度指数(Jgi)均表现为S1>S2>S3>S4,以上4个指数的变异系数分别为11.51%,1.84%,23.64%和1.55%;基于细菌多样性参数的聚类分析结果,将对照S1和添加Cr(Ⅵ)处理的S2归于一类,而2个添加Fe处理的土壤S3和S4聚为一类。【结论】经过10 d淹水处理,...

超积累观赏植物筛选及生态修复强化技术研究

近年来，我国土壤的重金属污染形势日益严峻，大量的重金属污染土壤亟待修复。而重金属污染土壤的植物修复技术已受到人们的普遍重视，将观赏植物应用于污染土壤修复方面的研究刚刚兴起，就已展现出巨大的发展潜力。本研究针对土壤重金属镉（Cd）、砷（As）严重污染的局面，以及目前发现的超积累观赏植物种类极少和修复能力有限的现状，通过模拟实验筛选方法，以观赏植物作为研究对象，力图从中筛选出Cd/As超积累植物；同时将施肥强化措施和络合强化技术联合使用，以提高观赏植物修复Cd污染土壤的效率，降低修复成本和可能造成的环境风险。 通过盆栽实验初步分析了18种观赏植物对Cd、As的耐性和积累特征，根据超积累植物应具备的4个基本特征，从中挑选出孔雀草、缨绒花、雏菊3种具备Cd超积累特征的潜力植物，并发现所有参试植物均不具备As超积累特征。 通过盆栽梯度实验、污染小区实验以及水培梯度实验进一步研究了3种潜力植物在不同生长环境中对Cd的耐性和积累特征。结果表明，孔雀草和缨绒花是Cd超积累植物，在一定Cd污染范围内，两种植物地上部Cd含量均达到了Cd超积累植物的临界含量标准，地上部Cd含量高于根部和土壤中Cd含量，且对Cd污染的耐性较强，完全符合Cd超积累植物的基本特征。而雏菊不是Cd超积累植物，只是一种具备部分超积累特征的Cd富集植物。 生态修复强化实验表明，铵态氮肥(NH4)2SO4和螯合剂EGTA的联合强化处理，不仅可以有效缓解螯合剂对植物的毒害，显著提高植物地上部生物量，还可以增强螯合剂促进植物吸收累积Cd的作用，最终大幅提高了孔雀草修复Cd污染土壤的效率，使其明显高于相同和加倍剂量的螯合剂处理。因此，基于铵态氮肥与螯合剂联合使用的强化修复措施，既提高了修复效率，又减少了螯合剂用量，从而降低了修复成本和环境风险，是一种高效、安全的生态修复强化措施。

多氯联苯污染土壤的钯/铁双金属还原和生物降解联合修复研究

本文以土壤为介质，以2,4,4′-三氯联苯、2,2′,5,5′-四氯联苯、2,2′4,5,5′-五氯联苯、2,2′,3,4,4′,5-六氯联苯和2,2′,3,4,4′,5,5′-七氯联苯为目标污染物，对钯/铁双金属、微生物及其联合修复多氯联苯污染土壤进行了研究。 对钯/铁双金属还原脱氯多氯联苯的影响因素和动力学进行了研究，研究结果表明：较高的钯化率、反应温度，弱酸性pH条件对脱氯反应有促进作用；在实验所考察的初始浓度范围内，脱氯效果与多氯联苯的初始浓度关系较小；而钯/铁双金属投加量则存在一个适宜值，不宜太高或太低。多氯联苯催化脱氯符合准一级反应动力学。反应速率与多氯联苯初始浓度关系很小；反应速率随钯化率、钯/铁投加量和反应温度升高而增大；初始pH为5.5时反应速率最快。且联苯环上氯取代数越少，越难以脱氯。 从受多氯联苯长期污染的土样中筛选出一株高效降解多氯联苯的细菌（H1），菌株初步鉴定为芽胞杆菌属。在本实验条件下，微生物对土壤中多氯联苯的降解较为适宜的条件为：微生物接种量10%、反应温度在30℃左右、pH在7左右。在此条件下，微生物对PCBs的降解，随初始浓度的增加，降解速率逐渐降；且随氯取代数目的增加，降解率逐渐降低。 采用化学和微生物方法联合修复多氯联苯污染土壤是可行的。经过钯/铁双金属和好氧微生物连续处理后，2,4,4′-三氯联苯和2,2′,5,5′-四氯联苯几乎被完全降解，而2,2′4,5,5′-五氯联苯、2,2′,3,4,4′,5-六氯联苯和2,2′,3,4,4′,5,5′-七氯联苯还原脱氯后生成的低氯代同系物（2,2′,5-三氯联苯）也很容易被微生物所降解。 利用GC-MS对多氯联苯的中间产物及最终产物的分析，推测多氯联苯降解的反应机理为：在钯/铁双金属——水体系中，铁作为还原剂给出电子，水为质子供体。在催化剂钯作用下，H+与铁给出的电子在双金属表面结合，形成具有高反应活性的中间产物——新生态H*。H *攻击多氯联苯取代联苯环上的氯形成脱氯产物和氯离子。反应体系中的溶解氧与溶解铁结合在钯/铁表面形成氧化层，阻碍反应进行。过多的H2气泡也会覆盖活性反应位，对脱氯反应不利。