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391.
392.
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. 相似文献
393.
采用盆栽试验法,研究了苏丹草对土壤中菲、芘的去除效果,及植物和微生物在去除土壤菲、芘中的交互效应。结果显示,在试验浓度范围(0-322.06mg·kg^-1内,土壤~苏丹草系统(TR,)对菲、芘的去除效果明显。种植苏丹草60d后,土壤菲、芘去除率分别为73.07%-83.92%、63%~77.62%;平均去除率分别比对照1(无植物,不加0.1%NaN3)高55.58%、50.71%,比对照2(无植物,加0.1%NaN3)高72.71%、66.57%,说明种植苏丹草可以促进微生物对土壤中芘、菲降解。土壤酶活性测定结果也显示,酶活性越高,污染物降解率越高,反之亦然。因此,植物一微生物间的交互效应是土壤中多环芳烃降解的主要途径。 相似文献
394.
重金属污染植物修复技术的研究进展 总被引:8,自引:0,他引:8
分别从植物修复的类型、超富集植物的筛选、超富集植物吸收富集重金属的生理和分子学机制等方面对国内外重金属污染植物修复技术研究进展进行综述,指出目前研究中存在的问题和今后的研究方向。 相似文献
395.
重金属污染的植物修复研究进展 总被引:1,自引:1,他引:1
植物重金属污染以及针对重金属污染的植物修复是近年来国际上环境治理的研究热点。以我国若干矿区植物或植被为例,综述了近年来植物重金属污染的研究状况,介绍了植物重金属耐性和超积累特性方面的研究进展,并对植物修复的研究前景提出了一些见解。 相似文献
396.
植物间作体系根际修复土壤多氯联苯的效应 总被引:2,自引:1,他引:2
以大豆、黑麦草和南瓜为材料,运用盆栽实验,通过3种植物的单作和间作对多氯联苯污染土壤的根际修复效应进行了研究。结果表明,植物不同种植方式均对根际土壤中PCB浓度的降解有促进作用,其中植物单作的去除率比CK提高了10.4%~17.0%,植物间作的去除率比CK提高18.4%~23.9%。南瓜-大豆体系中的大豆根的蓄积浓度显著差异高于其他处理,而与大豆南瓜间作方式下黑麦草根蓄积浓度均比其单作显著提高,大豆-南瓜和南瓜-黑麦草间作系统中的大豆和黑麦草根中PCB蓄积浓度也显著提高(P0.05)。各处理间根际土壤的pH、Eh、电导率的差异性规律性不大。相关分析结果表明,根际土壤PCB去除率与植物吸收量呈显著正相关,而与pH、Eh和电导率没有达到显著相关。 相似文献
397.
398.
海州香薷和紫花香薷对Cu、Zn的吸收和积累 总被引:13,自引:1,他引:13
采用水培试验方法,研究了Cu、Zn处理对海州香薷和紫花香薷(两种分别在铜矿和铅锌矿上良好生长的优势植物)生长及Cu、Zn吸收和积累的影响。结果表明,50μmol·L-1的Cu有利于海州香薷根系的生长,但却明显抑制紫花香薷地上部分的干物质产量,而Zn处理浓度直到200μmol·L-1也未对两种香薷的干物质量产生影响。低Cu(对照)时Zn的增加并未影响海州香薷地上部分Cu的含量和积累量,但高Cu(50和200μmol·L-1)时,Zn浓度的增加减少了海州香薷地上部分Cu的含量和积累量;而紫花香薷地上部分Cu含量和积累量无论是高Cu还是低Cu时都随Zn的增加而减少。同样,海州香薷和紫花香薷地上部分的Zn含量和积累量在低Zn时并未受Cu浓度的抑制,但在高Zn时,Cu的增加却减少了Zn含量的增加。而且海州香薷在高Cu(200μmol·L-1)和高Zn(200μmol·L-1)时对Cu和Zn的积累量明显高于紫花香薷,在Cu和Zn的修复上表现出优势。 相似文献
399.
报道了凤眼莲修复水溶液中乙硫磷、三氯杀螨醇和三氟氯氰菊酯的效果及主要机理.研究结果表明,10~11 g凤眼莲可将250 mL的1 mg/L的乙硫磷、三氯杀螨醇和三氟氯氰菊酯消解速度分别提高283.33%、106.64%和362.23%%.其修复机理主要是凤眼莲吸收农药后在体内积累或进一步降解,贡献率分别达69.28%、37.77%和63.06%%,而其中乙硫磷和三氯杀螨醇消解量的约60%由积累作用造成,积累对三氟氯氰菊酯的消解也起了约30%的作用.微生物的降解贡献率相对较小,分别占乙硫磷、三氯杀螨醇和三氟氯氰菊酯消解率的19.72%、13.93%和15.30%. 相似文献
400.
芸苔属蔬菜的Cd富集特性及其修复土壤Cd污染的潜力 总被引:22,自引:1,他引:22
通过温室水培13个小白菜和11个结球甘蓝品种,研究其对重金属镉(Cd)的富集特性.结果表明,在0(CK)、25、50、125、250μmol·L-15个不同Cd供应浓度下,不同芸苔属蔬菜品种的地上部Cd含量之间差异达极显著水平;且随Cd浓度的升高,不同品种对Cd的富集呈现一定规律:即单峰富集型、双峰富集型和递增型.以生物富集因子(BCF)为指标进行分析,则可分为2种类型:递减型和单峰型,前者BCF随Cd供应浓度升高而减小,最高BCF为146.85(品种Invinto);后者BCF随Cd供应浓度升高而升高,在50μmol·L-1出现一个峰值,随后BCF下降,最高BCF峰值达到72.95(品种94-N1).可见BCF是筛选修复土壤Cd污染植物材料的较为合适的指标.在本试验条件下,筛选出小白菜品种福绿1号、94-N1、日本华冠、日本冬妃、虹桥矮青和结球甘蓝品种Ducati、Matsumo、Gideon、Invinto可作为潜在修复土壤Cd污染的植物材料. 相似文献