EDDS对海州香薷修复重金属复合污染土壤的田间效应

两年田间小区试验研究了加入易降解络合剂EDDS后污染土壤及修复植物海州香薷地上部Cu、Zn、Pb含量及地下水水质变化。结果显示,添加EDDS能在一定程度上提高海州香薷对Cu、Zn、Pb的吸收量,但是对地下水水质影响不大,符合国家III类地下水水质标准。EDDS强化海州香薷修复复合污染土壤有一定的应用前景,且对于地下水的潜在淋滤风险较小,但是在应用期间应注意对环境因素特别是降水及地下水的影响。     

铜胁迫对海州香薷和紫花香薷根系形态及铜富集的影响

通过水培试验,研究了在不同Cu浓度处理条件下海州香薷和紫花香薷根系形态和植物各器官铜含量、累积量间的差异。结果表明:低浓度Cu处理(<50μmol/L)对海州香薷的生长有一定的促进作用,植株干重、根系长度、根系表面积、根体积和侧根均略有升高。但随着Cu浓度(100～500μmol/L)增加,表现出一定的负效应,海州香薷在500μmol/LCu处理时植株干重、根系长度、根系表面积、根体积和侧根明显受到抑制,与对照相比差异达显著或者极显著水平。紫花香薷在50μmol/LCu处理时根系生长就受到严重抑制,而当浓度再增加时,根系形态的各项指标则无明显变化。海州香薷地上部铜含量明显高于紫花香薷。     

铜锌铅复合污染土壤上香薷植物的生长和重金属吸收动态

盆栽试验研究了海州香薷和紫花香薷在Cu、Zn、Pb复合污染泥沙土上的重金属耐性与吸收动态。结果发现,在Cu、Zn、Pb全量分别为223、1068、232mg/kg的土壤上,两种香薷植物地上部生物量随生长时间的延长其增长趋势明显,其中叶片积累的生物量略高于茎秆积累的生物量;在整个生长期中重金属含量呈现动态变化,重金属吸收量有增加趋势。     

修复植物香薷堆肥对缺铜土壤上冬小麦生长和铜吸收的初步研究

通过堆积腐解处理生长在Cu污染土壤上的修复植物-海州香薷,将其研制成堆肥,作为基肥施用于缺Cu土壤,以矫正作物缺Cu症状。盆栽试验研究了这种堆肥对冬小麦(TriticumaestivumL.)生长和Cu吸收的影响。结果表明,施用海州香薷堆肥可显著提高生长在缺Cu土壤上的小麦的株高、生物量和籽实千粒重。与CK相比,千粒重可提高58.9%,籽实产量提高近1倍;而在这种缺Cu土壤上单纯施加N、P、K化肥,反而降低小麦生物量和籽实千粒重。可见,将Cu污染土壤上生长的修复植物海州香薷制成堆肥,施用于缺Cu土壤是一种可实现修复植物资源化的有效途径。     

海州香薷和鸭跖草铜吸收机理

研究了解偶联剂、P-型ATP酶抑制剂、离子通道抑制剂、蛋白合成抑制剂和缺铁缺锌诱导对海州香薷(Elsholtzia.splendens)和鸭跖草(Commelina.communis)铜吸收的影响。结果表明,海州香薷对铜的富集能力高于鸭跖草,但鸭跖草对铜的运输能力大于海州香薷。解偶联剂2,4.二硝基苯酚(DNP)和P-型ATP酶抑制剂钒酸钠(Na3VO4)对海州香薷和鸭跖草铜吸收均有一定的抑制作用,说明两种植物对铜可能存在主动吸收。钙离子通道抑制剂LaCl3对海州香薷铜吸收有抑制作用,而对鸭跖草铜吸收没有抑制作用;蛋白合成抑制剂放线菌酮(CHD)对海州香薷铜吸收没有抑制作用,而显著抑制了鸭跖草对铜的吸收。说明海州香薷铜吸收与钙离子通道密切相关。缺铁诱导大大提高了海州香薷与鸭跖草对铜的吸收。低浓度铜处理下,缺锌诱导对两种植物铜吸收影响不大;但高浓度铜处理下,缺锌诱导促进了铜吸收。     

不同铜污染土壤上海州香薷生长及铜吸收动态

盆栽试验表明,生长期内海州香薷植物体内Cu含量呈现2个随着不同处理中Cu浓度的提高而斜率递增的阶段;海州香薷植株内Cu含量对外界Cu浓度的响应曲线以200mg/kg为转折点,当Cu浓度>200mg/kg时曲线斜率显著增加。在开花初期,Cu400处理污染土壤中Cu清除量达到最大值27.2mg/盆,其污染土壤重金属去除率仅为1.30%。而盛花期,各处理污染土壤中海州香薷植物内Cu含量均明显高于开花初期,Cu400处理污染土壤中Cu清除量达到最大值143mg/盆,其污染土壤重金属去除率达6.85%,与开花初期差异显著(p<0.05)。     

香薷属植物在重金属修复中的应用进展

香薷属植物应用于重金属修复经历了矿区植物资源调查和比较、室内模拟研究、田间规模修复以及修复后处置研究,已经初步形成一个植物修复技术的完整体系。在现有技术条件下,把生态修复模式、品种驯化及诱导剂"配方"应用到香薷属植物修复土壤重金属污染对提高修复效率具有重要意义。     

可降解络合剂及微生物调控对海州香薷修复污染土壤的效应

盆栽试验研究了海州香薷在Cu、Zn、Pb污染土壤上生长和对Cu、Zn、Pb的富集能力,以及调控剂EDDS、壳聚糖和微生物菌剂对海州香薷重金属吸收的影响。结果表明,Cu223mg/kg,Pb232mg/kg,Zn1068mg/kg的重金属复合污染土壤对海州香薷的生长发育没有明显影响。施用EDDS(3mmol/kg土) 微生物制剂处理组海州香薷叶片中Cu含量高达847mg/kg,Zn含量为745mg/kg;Cu吸收量高达6244μg/株,Zn吸收量为5670μg/株,叶片中Cu、Zn的含量和吸收量均极显著高于对照(p<0.01);3mmol/kg土EDDS处理海州香薷茎中Pb含量显著增加(p<0.05),茎中Pb的吸收量亦显著提高(p<0.05),茎秆中Pb的吸收量为274μg/株。微生物制剂或壳聚糖单独处理对海州香薷生长和金属元素吸收均没有明显的效果。     

无色菌产酸对土壤溶液重金属浓度及海州香薷重金属吸收的影响

利用培养试验和盆栽试验研究了一株无色菌(Achromatium sp.)对复合污染土壤上Cu、Zn的溶出效果及其对海州香薷(Elsholtzia splendens)生长和Cu、Zn吸收性的影响.结果表明,菌株在培养试验(pH = 4.65)中的产酸效果较盆栽试验(7.3＜pH＜8.2)更佳;土壤溶液可溶性Cu与pH显著正相关,而可溶性Zn与pH显著负相关;和对照处理相比,无色菌处理提高海州香薷的生物量和地上部Cu浓度,显著(p＜0.05)提高海州香薷对污染土壤中Cu的去除潜力.     

重金属污染土壤生态工程修复的试验研究

该文研究了细叶香薷(Moslem chinensis Maxim)和构树(Broussonetia papyrifera(Linn.) Vent.)对Cu、Zn污染土壤的修复及污染土壤对植物生理性状的影响。研究结果表明：随着盆栽土壤中重金属浓度的增高，植物体内吸收重金属的浓度相应增大。Cu在细叶香薷体内的含量是地上部＜地下部，Zn含量却是地上部＞地下部；重金属Cu、Zn在构树体内的浓度都是根部＞叶部＞茎部。细叶香薷的富集系数基本大于1，对Cu的最大富集系数是2.42；构树的富集系数都在0.5以下，但由于其地上部生物量很大，从土壤中移除的重金属量也很可观，而且构树能产生经济价值，建议把构树和细叶香薷组成一个立体的生态工程修复模式，既能修复污染土壤又能恢复污染地区的生态环境和土壤微生物环境，产生经济和环境效益。     

两种矿山生态型香薷对铜的吸收、分布和积累特性研究

Two ecotypes of Elsholtzia, Elsholtzia splendens and E. argyi, are dominant plants growing on Cu and Pb-Zn smelters, respectively. Samples of the two ecotypes and the corresponding soils from fields of a copper mining area and a Pb-Zn mining area of Zhejiang Province, China, were analyzed to investigate Cu or Zn tolerance of these two ecotypes. Effects of nine Cu levels (0, 5, 10, 20, 40, 80, 160, 240 and 320 mg Cu L^-1 as CuSO₄·5H₂O) on growth and uptake, translocation and accumulation of Cu in these two ecotypes were examined in a solution culture experiment. The experimental results showed that dry weights (DW) of shoots and roots were depressed, and growth of E. splendens was less depressed than that of E. argyi when treated with ≥ 5 mg Cu L^-1. Concentrations of Cu in shoots of E. splendens and E. argyi exceeded 1 000 mg kg^-1 DW at ≥ 40 mg Cu L^-1. The maximum Cu accumulated in the shoots of Cu-treated E. splendens and E. argyi reached 101 and 142 μg plant^-1. Furthermore, analysis of plant samples from the fields showed that these two ecotypes can tolerant excess heavy metals and produced high dry matter, and E. splendens can accumulate 11.7 mg Cu plant^-1 grown on the Cu smelter. Therefore, E. splendens and E. argyi could be good plants for phytoremediation.     

植被恢复对重金属污染土壤有机质及团聚体特征的影响

采用田间原位试验,研究了不同植被恢复3年对重金属污染土壤有机碳及团聚体结构和稳定性的影响,评价了不同植物修复效果的差异,为农田重金属污染土壤修复中,合理选择植被类型,以及建立评价标准提供理论依据。在某Cu,Cd重度污染农田建立田间小区,施加钝化材料石灰(对照除外)后种植海州香薷(ME),伴矿景天(MS)和巨菌草(MP)3种植物,3年的田间原位修复试验后,分析各处理下土壤有机质含,0.25 mm机械稳定性团聚体(DR_(0.25))和水稳定性(WR_(0.25))团聚体含量,团聚体平均质量直径(MWD),几何平均直径(GMD),团聚体稳定率(AR,%)和分形维数(D)等团聚体稳定性指标。结果表明,3年植被恢复后,3种植被处理均提高了土壤有机质含量,提高幅度为2.89%~5.39%,并提高了0.25mm机械稳定性团聚体(DR_(0.25))和水稳定性(WR_(0.25))团聚体含量,提高幅度分别为2.89%~5.39%,6.64%~10.40%和13.34%~17.48%。3种植物处理均可以显著提高土壤机械稳定性团聚体和水稳性团聚体的平均质量直径(MWD)和几何平均直径(GMD),其中以巨菌草处理提高幅度最大。在团聚体稳定性方面,3种植物处理均可以提高团聚体的稳定率(AR,%),以海州香薷处理提高幅度最大;植物处理可以显著降低土壤机械稳定性团聚体的分形维数(D),但对水稳定性团聚体的分形维数没有明显的影响。综上所述,采用钝化加原位植物修复可以提高重金属重度污染农田的有机质含量和土壤团聚体的稳定性,改善土壤结构,可以在重金属重度污染土壤修复中推广应用。     

共培养对土壤重金属污染植物修复的调控作用

A co-culture of two plant materials, Astragalus sinicus L., a leguminous plant with concomitant nodules, and Elsholtzia splendens Naki-a Cu accumulator, along with treatments of a chelating agent (EDTA), root excretions (citric acid), and a control with E. splendens only were used to compare the mobility of heavy metals in chelating agents with a co-culture and to determine the potential for co-culture phytoremediation in heavy metal contaminated soils. The root uptake for Cu, Zn, and Pb in all treatments was significantly greater (P < 0.05) than that of the control treatment. However with translocation in the shoots, only Cu, Zn, and Pb in plants grown with the EDTA treatment and Zn in plants co-cropped with the A. sinicus treatment increased significantly (P < 0.05). In addition, when a co-culture in soils with heavy and moderate contamination was compared, for roots in moderately contaminated soils only Zn concentration was significantly less (P < 0.05) than that of heavily contaminated soils, however, Cu, Zn, and Pb concentrations of shoots were all significantly lower (P < 0.05). Overall, this "co-culture engineering" could be as effective as or even more effective than chelating agents, thereby preventing plant metal toxicity and metal leaching in soils as was usually observed in chelate-enhanced phytoremediation.     

Variation in community structure of arbuscular mycorrhizal fungi associated with a Cu tolerant plant—Elsholtzia splendens

Little is known about the characteristics of arbuscular mycorrhizal fungi (AMF) community in the roots of host plants growing on heavy metal contaminated sites. The objectives of this study were to examine the community structure of AMF associated with the roots of a copper (Cu) tolerant plant—Elsholtzia splendens in a Cu mining area in southeastern Anhui Province, China. Molecular techniques were used to analyze AMF community composition and phylogenetic relationship in E. splendens roots sampled from three Cu mine spoils and two adjacent reference areas. Results obtained showed that root colonization and AMF diversity were very low and negatively correlated with total and extractable Cu concentrations. All the DNA sequences recovered belonged to the genus of Glomus. The principal component analysis (PCA) revealed that the AMF community composition varied remarkably among different sites and was related closely to soil properties, especially Cu concentrations. The distribution pattern of AMF species in various sites suggested the degree of AMF tolerance to Cu contamination. The unique AMF species that presented exclusively in heavily contaminated sites need to be further examined for potential application in phytoremediation of metal contaminated soils.     

Field-Scale Assessment of Phytotreatment of Soil Contaminated with Weathered Hydrocarbons and Heavy Metals (9 pp)

Background, Aim and Scope   Phytoremediation is a remediation method which uses plants to remove, contain or detoxify environmental contaminants. Phytoremediation has successfully been applied for the removal of fresh hydrocarbon contamination, but removal of aged hydrocarbons has proven more difficult. Biodegradation of hydrocarbons in the subsurface can be enhanced by the presence of plant roots, i.e. the rhizosphere effect. Phytostabilization reduces heavy metal availability via immobilization in the rhizosphere. Soils contaminated by both hydrocarbons and heavy metals are abundant and may be difficult to treat. Heavy metal toxicity can inhibit the activity of hydrocarbon-degrading microorganisms and decrease the metabolic diversity of soil bacteria. In this experiment, weathered hydrocarbon- and heavy metal- contaminated soil was treated using phytoremediation in a 39- month field study in attempts to achieve both hydrocarbon removal and heavy metal stabilization. Materials and Methods: A combination of hydrocarbon degradation and heavy metal stabilization was evaluated in a field-scale phytoremediation study of weathered contaminants. Soil had been contaminated over several years with hydrocarbons (11400±4300 mg kg dry soil)-1 and heavy metals from bus maintenance activities and was geologically characterized as till. Concentrations of soil copper, lead and zinc were 170±50 mgkg-1, 1100±1500 mg kg-1 and 390±340 mg kg-1, respectively. The effect of contaminants, plant species and soil amendment (NPK fertilizer or biowaste compost) on metabolic activity of soil microbiota was determined. Phytostabilization performance was investigated by analyses of metal concentrations in plants, soil and site leachate as well as acute toxicity to Vibrio fischeri and Enchtraeus albidus. Results: Over 39 months hydrocarbon concentrations did not decrease significantly (P=0.05) in non-amended soil, although 30% of initial hydrocarbon concentrations were removed by the last four months of study. In soil amended with NPK fertilizer and municipal biowaste compost, 65 % and 60 % of hydrocarbons were removed, respectively. The soil contained metabolically diverse bacteria, measured as carbon source utilization and extracellular enzymatic activities. Compost addition resulted in a slight increase in enzymatic activities. Diesel fuel utilization potential in Biolog MT2 plates inoculated with a soil suspension was enhanced by both compost and NPK compared to non-amended soil. Soil toxicity to V. fischeri and E. albidus was low. The leachate was not toxic to V. fischeri. Pine (Pinus sylvestris), poplar (Populus deltoides x Wettsteinii), grasses and clover (Trifolium repens) survived to varying degrees in the contaminated soil. All plants suffered from phytotoxicity symptoms and some trees died during the study period. Plants formed a dense cover over the compost-amended soil, whereas non-amended soil had areas devoid of vegetation throughout the study. Vegetation coverage in the NPK-amended quarter was about 50 % after the first four months of study, but increased gradually to 100 %. Heavy metals did not accumulate in plant tissue. Discussion: Removal of hydrocarbons from weathered unfertilized hydrocarbon-contaminated soil was not statistically significant despite the presence of a viable hydrocarbon-degrading microbial community. This effect is attributed to soil heterogeneity and low bioavailability of hydrocarbons. Hydrocarbon concentrations were not reduced to the desired level, i.e., 1500 mg hydrocarbons (kg of dry soil)-1, in any treatment. . The presence of clay minerals and organic matter within the compost may have limited heavy metal transfer to leachate and plant tissue. Conclusions: Weathered hydrocarbons were partly decomposed in soil fertilized with NPK fertilizer or biowaste compost, but not from unfertilized soil. The active hydrocarbon-degrading microbiota and low toxicity of soil to V. fischeri and E. albidus indicates low availability of contaminants to microorganisms. Despite high heavy metal concentrations, the soil contained metabolically diverse bacteria, measured as carbon source utilization and extracellular enzymatic activities. Heavy metals did not accumulate in test plants. Pine and poplar suffered from phytotoxicity symptoms in the soil and could not enhance hydrocarbon removal in compost-amended soil. Compost addition combined with a grass and legume crop is suggested for stabilization of combined hydrocarbon- and metal-contaminated soil. Recommendations and Perspectives: Both compost and NPK fertilizers can be used to enhance phytoremediation of soil contaminated with weathered hydrocarbons in the presence of heavy metals; however, compost addition is recommended since it enables greater vegetative coverage. This in turn may decrease heavy metal mobility. Phytoremediation can be used for remediation of soil contaminated with weathered hydrocarbons in the presence of heavy metals. However, phytoremediation of weathered contaminants requires extended periods of time; thus, other remediation methods should be considered in the event of soil contamination posing an immediate public health and/or environmental threat.