Concurrent sorption of Zn(II), Cu(II) and Co(II) by Oscillatoria angustissima as a function of pH in binary and ternary metal solutions

This paper reports biosorption of Zn(II), Cu(II) and Co(II) onto O. angustissima biomass from single, binary and ternary metal solutions, as a function of pH and metal concentrations via Central Composite Design generated by statistical software package Design Expert 6.0. The experimental design revealed that metal interactions could be best studied at lower pH range i.e. 4.0-5.0, which facilitates adequate availability of all the metal ions. The sorption capacities for single metal decreased in the order Zn(II)>Co(II)>Cu(II). In absence of any interfering metals, at pH 4.0 and an initial metal concentration of 0.5 mM in the solution, the adsorption capacities were 0.33 mmol/g Zn(II), 0.26 mmol/g Co(II) and 0.12 mmol/g Cu(II). In a binary system, copper inhibited both Zn(II) and Co(II) sorption but the extent of inhibition of former was greater than the latter; sorption values being 0.14 mmol/g Zn(II) and 0.27 mmol/g Co(II) at initial Zn(II) and Co(II) concentration of 1.5 mM each, pH 4.0 and 1mM Cu(II) as the interfering metal. Zn(II) and Co(II) were equally antagonistic to each others sorption; Zn(II) and Co(II) sorption being 0.23 and 0.24 mmol/g, respectively, at initial metal concentration of 1.5 mM each, pH 4.0 and 1mM interfering metal concentration. In contrast, Cu(II) sorption remained almost unaffected at lower concentrations of the competing metals. Thus, in binary system inhibition dominance observed was Cu(II)>Zn(II), Cu(II)>Co(II) and Zn(II) approximately Co(II), due to this the biosorbent exhibited net preference/affinity for Cu(II) sorption over Zn(II) or Co(II). Hence, the affinity series showed a trend of Cu(II)>Co(II)>Zn(II). In a ternary system, increasing Co(II) concentration exhibited protection against the inhibitory effect of Cu(II) on Zn(II) sorption. On the other hand, the inhibitory effect of Zn(II) and Cu(II) on Co(II) sorption was additive. The model equation for metal interactions was found to be valid within the design space.     

Biosorption of nickel and cadmium by metal resistant bacterial isolates from agricultural soil irrigated with industrial wastewater

Agricultural soil irrigated with industrial wastewater (more than two decades) analysed for heavy metals revealed high levels of Fe, Cr, Cu, Zn, Ni and Cd. Out of a total of 40 bacterial isolates obtained from these soils, 17 belonged to the family enterobacteriaceae and 10 were Pseudomonas spp. A maximum MIC of 200 for Cd, 400 for Zn and Cu, 800 for Ni, and 1600 microg/ml for Pb was observed. Biosorption of Ni and Cd studies over a range of metal ion concentrations with Escherichia coli WS11 both in single and bi-metal systems showed that the adsorption of Cd and Ni was dependent on the concentrations and followed the Freundlich adsorption isotherm. The biosorption of Ni increased from 6.96 to 55.31 mg/g of cells, and Cd from 4.96 to 45.37 mg/g of cells at a concentration ranging from 50 to 400 microg/ml after 2h of incubation in a single metal solution. A further increase in incubation time had no significant effect on the biosorption of metals.     

Interaction of Pseudomonas putida CZ1 with clays and ability of the composite to immobilize copper and zinc from solution

The present study was conducted to determine the abilities of the living and nonliving Pseudomonas putida CZ1 cells, clays (goethite, kaolinite, smectite and manganite) and their composites to accumulate copper and zinc from a liquid medium, and elucidate the role of microbes on the mobility of heavy metals. Various mixtures of bacteria and clays were exposed to solutions of 0.025 mM or 0.5mM Cu(II) and Zn(II) in 0.01M KNO(3) to differentiate between so-called "high-affinity" sites and "low-affinity" sites. Clays associated in an edge-on orientation to the cells was observed by electron microscope (EM) examination of these metal-treated bacteria-clay aggregates. Adsorption experiments and desorption with 1.0M CH(3)COOK solution indicated that clays contain more high-affinity copper binding sites and less high-affinity zinc binding sites than that of bacteria, however, bacteria are involved in more low-affinity heavy-metal-binding sites. Carboxyl group activity is more important at weak-binding sites than at strong-binding sites. TEM-EDS analysis confirmed that most of Zn removed from solution was associated with P. putida CZ1 in the composites. These results suggest that bacteria play an important role in regulating the mobility of heavy metals in the soil environment.     

蛋白酶分泌菌对重金属胁迫的反应

本文研究了Pb、Zn、Cu和Cd对3种蛋白酶产生菌：碱性地衣芽孢杆菌2709(Bacillus licheniformis 2709)、中性枯草杆菌1.398(Bacillus subtilis1.398)和酸性宇佐美曲霉537(Aspergillus usamii 537)生长及其酶活性的影响, 并采用生长抑制皿分析(GIPA)方法针对3种菌株在Pb、Zn、Cu、Cd不同胁迫浓度下的生长量进行打分, 分析其耐性与抗性指标(MTC与MIC)。结果表明4种重金属在超过一定临界浓度后, 对3种菌株的生长和蛋白酶活性均产生了较大的抑制作用。碱性蛋白酶对4种重金属均具有较大的适应性, 其次是中性蛋白酶对Zn和Cd具有一定的适应性, 而酸性蛋白酶对4种重金属均表现出被抑制状态。3种菌株对Pb和Zn耐性与抗性最高(2.0 mmol/L~6.0 mmol/L), 其次是对Cd也具有一定的抗性(0.5 mmol/L~0.75 mmol/L)。     

蛋白酶分泌菌对重金属胁迫的反应

本文研究了Pb、zn、cu和Cd对3种蛋白酶产生菌:碱性地衣芽孢杆菌2709(Bacilluslicheniformis 2709)、中性枯草杆菌1.398(Bacillus subtilis1.398)和酸性宇佐美曲霉537(Aspergillususamii 537)生长及其酶活性的影响,并采用生长抑制皿分析(GIPA)方法针对3种菌株在Pb、zn、Cu、Cd不同胁迫浓度下的生长量进行打分,分析其耐性与抗性指标(MTC与MIC).结果表明4种重金属在超过一定临界浓度后,对3种菌株的生长和蛋白酶活性均产生了较大的抑制作用.碱性蛋白酶对4种重金属均具有较大的适应性,其次是中性蛋白酶对Zn和Cd具有一定的适应性.而酸性蛋白酶对4种重金属均表现出被抑制状态.3种菌株对Pb和Zn耐性与抗性最高(2.0 mmol/L～6.0 mmol/L),其次是对Cd也具有一定的抗性(0.5 mmol/L～0.75 mmol/L).     

Biosorption of chromium, copper, manganese and zinc by Pseudomonas aeruginosa AT18 isolated from a site contaminated with petroleum

The study describes the sorption of Cr, Cu, Mn and Zn by Pseudomonas aeruginosa AT18 isolated from a site contaminated with petroleum and heavy metals. The concentrations studied were 50, 49, 60 and 70 (mg L(-1)) for Cr, Cu, Mn and Zn, respectively. The solution pH and ionic strength were very important factors in the metal biosorption performance and the biosorption capacity of P. aeruginosa AT18 for Cr3+,Cu2+, Mn2+ and Zn2+. In aqueous solution, the biosorption increased with increasing pH in the range 5.46-7.72. The results obtained in the experimental assays show that P. aeruginosa AT18 has the capacity for biosorption of the metallic ions Cr3+, Cu2+ and Zn2+ in solutions, although its capacity for the sorption of manganese is low (22.39 mg Mn2+/g of biomass) in comparison to the Cr3+, Cu2+ and Zn2+ ions, as shown by the individual analyses. However, 20% of the manganese was removed from an initial concentration of 49.0 mg L(-1), with a Qm value similar to that obtained in solutions containing mixtures of Cr3+, Cu2+, Mn2+and Zn2+. The chromium level sorbed by P. aeruginosa AT18 biomass was higher than that for Cu, Mn and Zn, with 100% removal in the pH range 7.00-7.72 and a Qm of 121.90-200.00 mg of Cr3+/g of biomass. The removal of Cr, Cu and Zn is also a result of precipitation processes.     

Biosorption of Heavy Metals from Wastewater by Biosolids

In a study where the removal of heavy metals from wastewater is the primary aim, the biosorption of heavy metals onto biosolids prepared as Pseudomonas aeruginosa immobilized onto granular activated carbon was investigated in batch and column systems. In the batch system, adsorption equilibriums of heavy metals were reached between 20 and 50 min, and the optimal dosage of biosolids was 0.3 g/L. The biosorption efficiencies were 84, 80, 79, 59 and 42 % for Cr(VI), Ni(II), Cu(II), Zn(II) and Cd(II) ions, respectively. The rate constants of biosorption and pore diffusion of heavy metals were 0.013–0.089 min^–1 and 0.026–0.690 min^–0.5. In the column systems, the biosorption efficiencies for all heavy metals increased up to 81–100 %. The affinity of biosorption for various metal ions towards biosolids was decreased in the order: Cr = Ni > Cu > Zn > Cd.     

Biosorption of Cu(II) and Pb(II) ions from aqueous solution by natural spider silk

Aside from its excellent mechanical properties, spider silk (SS) would offer an active surface for heavy metal interaction due to its rich protein structure. The present study describes the potential use of natural (SS) as a sorbent of heavy metals from aqueous solutions. Single and multi-species biosorption experiments of heavy metals by natural SS were conducted using batch and column experiments. The biosorption kinetics, in general, was found to follow the second-order rate expression, and the experimental equilibrium biosorption data fitted reasonably well to Freundlich isotherm. From the Freundlich isotherm, the biosorption capacities of Cu(II) and Pb(II) ions onto SS were found as 0.20 and 0.007 mmol g?1, respectively. The results showed a decrease in the extent of metal ion uptake with lowering the pH.     

Biotechnological potential of Microcystis sp. in Cu, Zn and Cd biosorption from single and multimetallic systems

This paper provides information on biosorption of Cu, Zn and Cd by Microcystis sp. in single, bi and trimetallic combination. Highest biosorption of Cu followed by Zn and Cd in single as well as in mixtures containing two or three metals was noticed. The order of inhibition of Cu, Zn and Cd biosorption in bi and trimetallic combinations was suggestive of screening or competition for the binding sites on the cell surface. This observation was reconfirmed by Freundlich adsorption isotherm. K_f values were maximum for Cu (K_f=45.18), followed by Zn (K_f=16.71), and Cd (K_f=15.63) in single metallic system. The K_f values for each test metal was reduced in solution containing more than one metal. Further, the reduction in biosorption of each metal ion due to presence of other metal ion was of greater magnitude at relatively higher concentrations of interfering metal ion. The biosorption of Cu at saturation was less affected when secondary metal (Cd or Zn) was added in the medium. Above results suggest that Microcystis holds great potential for metal biosorption from mixture.     

重金属诱导拟南芥原生质体DNA 损伤的单细胞凝胶电泳检测

以拟南芥原生质体为实验体系, 研究不同浓度的3种重金属离子对拟南芥原生质体的毒性和DNA损伤的差异。结果表明, 用1-5 mmol.L-1的Zn2+、Cd2+ 和Cu2+分别处理的拟南芥原生质体, 2 小时内活力逐渐下降, 并表现出明显的浓度依赖性;与相同浓度的Cd2+ 和Cu2+ 相比, Zn2+对拟南芥原生质体活力的影响程度较小, 表现出较低的毒性。单细胞凝胶电泳检测发现,用0.1-0.8 mmol .L-1的Zn2+、Cd2+ 和Cu2+ 分别处理拟南芥原生质体30 分钟, 以OTM值表示的原生质体DNA损伤量随重金属离子浓度的增加而递增; 相同浓度(0.5 mmol.L-1)的3种重金属离子相比, Zn2+对原生质体的遗传毒性明显低于Cu2+ 和Cd2+。综合原生质体活力和DNA损伤的单细胞凝胶电泳检测结果, 发现Zn2+对拟南芥原生质体的遗传毒性较低, 而Cd2+ 和Cu2+的遗传毒性较高。本研究建立的拟南芥原生质体实验体系, 结合运用单细胞凝胶电泳技术, 能够快速、灵敏地检测重金属对植物细胞的遗传毒性。     

重金属对油菜种子萌发和胚根生长的影响

分析了Hg2 、Cd2 、Ni2 、Co2 、Zn2 5种重金属离子对油菜种子萌发和胚根伸长的影响,以及金属离子K 、Mg2 和Ca2 与重金属的交互作用。结果表明:(1)重金属对油菜种子萌发的抑制作用依次为Hg2 >Cd2 和Co2 >Ni2 >Zn2 ,而对胚根生长的毒害作用依次为Hg2 >Cd2 >Co2 >Ni2 >Zn2 。(2)萌发率为40%以上时,K 和Ca2 可以提高Ni2 、Zn2 和Co2 胁迫下油菜种子的萌发率,却进一步降低了Hg2 、Cd2 胁迫下种子的萌发;Mg2 可以提高Ni2 、Zn2 、Cd2 和Co2 胁迫下种子的萌发率,但对Hg2 毒害却没有缓解。(3)胚根伸长率达到60%以上时,K 和Mg2 增强了Ni2 、Hg2 、Cd2 和Co2 对胚根生长的抑制,而Ca2 则缓解了Zn2 、Ni2 和Co2 对胚根生长的抑制作用。研究结果对于重金属复合污染土壤中植物种子的萌发和定植具有理论和实践意义。     

Biodegradation of Metal-Nitrilotriacetate Complexes by a Pseudomonas Species: Mechanism of Reaction

A nitrilotriacetate (NTA)-degrading Pseudomonas species was shown to degrade Ca, Mn, Mg, Cu, Zn, Cd, Fe, and Na chelates of NTA at nearly equal rates when the appropriate metal concentrations are low enough to avoid toxicity from the freed metal. Ni-NTA, however, was not degraded. When higher concentrations of metal-NTA substrates were used, soil stimulated degradation of Cu, Zn, and Cd complexes, probably as a result of binding toxic freed metals. The metal associated with the NTA substrate does not appear to be transported into the cell, since metals do not accumulate in the cells and the presence of NTA reduces metal toxicity. The data are consistent with the hypothesis that an envelope-associated component, probably a transport protein involved in binding, is responsible for the disassociation of the metal from the NTA. Both soil and this NTA-degrading organism destabilize the metal-NTA complex, which suggests that in the natural environment both would act to limit mobilization of metals as soluble NTA chelates. Crude soluble enzyme preparations degrade Fe-, Mn-, and Na-NTA complexes but not Cu-NTA.     

Gene transfer in bacteria from soils contaminated with heavy metals

Transfer of metal resistance plasmids into two pseudomonad recipients, Pseudomonas aureofaciens and Ps. putida , from soil bacteria donor populations, was investigated in agricultural soil contaminated predominantly with Zn and Cu. The putative donor and recipient numbers on selective agar were not affected by the concentration of metals in the soils, nor were the number of transconjugants. However, there were differences in transfer frequencies of Hg and Cu resistance from the different soil samples. This is the first time that transfer of Cu resistance has been observed from native bacteria present in agricultural soils.     

Influences on copper bioaccumulation,growth, and survival of the midge,Chironomus tentans,in metal-contaminated sediments

Sediment bioassays with larvae of the midge, Chironomus tentans, were used to evaluate influences on the bioavailability and toxicity of copper (Cu) in sediments with a wide range of concentrations of metals, acid-volatile sulfide (AVS), and other physicochemical characteristics. Sediments were collected from sixteen lakes in Michigan, USA, and from twelve sites in the Clark Fork River drainage of Montana, USA, which are contaminated with metals from mining activities and from other anthropogenic sources. Bioassays with C. tentans larvae were conducted for ten days in a static-renewal test system, with endpoints of survival, growth, and metal bioaccumulation. Bioaccumulation of copper (Cu) was strongly correlated with Cu concentrations in porewater, and was increased significantly at Cu concentrations less than those affecting growth or survival. Midge survival and growth were not significantly correlated with concentrations of Cu in sediment or porewater, and were poorly predicted by ratios of acid-extractable metals to AVS in sediments. Principal components analysis indicated that Cu concentrations in porewater and bioaccumulation of Cu by midge larvae were influenced by AVS, sediment organic carbon, and porewater pH, and that toxicity was associated with high concentrations of Cu, high concentrations of zinc (Zn) and ammonia. No toxicity was observed in several sediments which contained low concentrations of AVS and high concentrations of Cu and Zn. In sediments which contain little AVS, bioavailability of metals may be controlled by constituents other than sulfides, such as organic matter and metal hydrous oxides. These results indicate that assessments of toxicity in metal-contaminated sediments should evaluate the importance of metal-binding phases other than sulfides, and the possible contributions of ammonia or other toxicants to toxicity in sediment bioassays.The U.S. Government right to retain a non-exclusive, royalty-free licence in and to any copyright is acknowledged.     

Localization effect on the metal biosorption capability of recombinant mammalian and fish metallothioneins in Escherichia coli

In this study, we examined the expression of mammalian and fish metallothioneins (MTs) in Escherichia coli as a strategy to enhance metal biosorption efficiency of bacterial biosorbents for lead (Pb), copper (Cu), cadmium (Cd), and zinc (Zn). In addition, MT proteins were expressed in either the cytoplasmic or periplasmic compartment of host cells to explore the localization effect on metal biosorption. The results showed that MT expression led to a significant increase (5-210%) in overall biosorption efficiency (eta(ads)), especially for biosorption of Cd. The MT-driven improvement in metal biosorption relied more on the increase in the biosorption rates (r(2), a kinetic property) than on the equilibrium biosorption capacities (q(max), a thermodynamic property), despite a 10-45% and 30-80% increase in q(max) of Cd and Zn, respectively. Periplasmic expression of MTs appeared to be more effective in facilitating the metal-binding ability than the cytoplasmlic MT expression. Notably, disparity of the impacts on biosorption ability was observed for the origin of MT proteins, as human MT (MT1A) was the most effective biosorption stimulator compared to MTs originating from mouse (MT1) and fish (OmMT). Moreover, the overall biosorption efficiency (eta(ads)) of the MT-expressing recombinant biosorbents was found to be adsorbate-dependent: the eta(ads) values decreased in the order of Cd > Cu > Zn > Pb.     

Improving the sensitivity of bacterial bioreporters for heavy metals

Whole-cell bacterial bioreporters represent a convenient testing method for quantifying the bioavailability of contaminants in environmental samples. Despite the fact that several bioreporters have been constructed for measuring heavy metals, their application to environmental samples has remained minimal. The major drawbacks of the available bioreporters include a lack of sensitivity and specificity. Here, we report an improvement in the limit of detection of bacterial bioreporters by interfering with the natural metal homeostasis system of the host bacterium. The limit of detection of a Pseudomonas putida KT2440-based Zn/Cd/Pb-biosensor was improved by a factor of up to 45 by disrupting four main efflux transporters for Zn/Cd/Pb and thereby causing the metals to accumulate in the cell. The specificity of the bioreporter could be modified by changing the sensor element. A Zn-specific bioreporter was achieved by using the promoter of the cadA1 gene from P. putida as a sensor element. The constructed transporter-deficient P. putida reporter strain detected Zn(2+) concentrations about 50 times lower than that possible with other available Zn-bioreporters. The achieved detection limits were significantly below the permitted limit values for Zn and Pb in water and in soil, allowing for reliable detection of heavy metals in the environment.     

Biosorption with algae: a statistical review

The state of the art in the field of biosorption using algae as biomass is reviewed. The available data of maximum sorption uptake (qmax) and biomass-metal affinity (b) for Cd2 +, Cu2 +, Ni2 +, Pb2 + and Zn2 + were statistically analyzed using 37 different algae (20 brown algae, 9 red algae and 8 green algae). Metal biosorption research with algae has used mainly brown algae in pursuit of treatments, which improve its sorption uptake. The information available in connection with multimetallic systems is very poor. Values of qmax were close to 1 mmol/g for copper and lead and smaller for the other metals. Metal recovery performance was worse for nickel and zinc, but the number of samples for zinc was very small. All the metals except lead present a similar affinity for brown algae. The difference in the behavior of lead may be due to a different uptake mechanism. Brown algae stand out as very good biosorbents of heavy metals. The best performer for metal biosorption is lead.     

Ultrastructural localization of heavy metals in the extraradical mycelium and spores of the arbuscular mycorrhizal fungus Glomus intraradices

Arbuscular mycorrhizal fungi, obligate symbionts of most plant species, are able to accumulate heavy metals, thereby, protecting plants from metal toxicity. In this study, the ultrastructural localization of Zn, Cu, and Cd in the extraradical mycelium and spores of the arbuscular mycorrhizal fungus Glomus intraradices grown in monoxenic cultures was investigated. Zinc, Cu, or Cd was applied to the extraradical mycelium to final concentrations of 7.5, 5.0, or 0.45 mmol/L, respectively. Samples were collected at time 0, 8 h, and 7 days after metal application and were prepared for rapid freezing and freeze substitution. Metal content in different subcellular locations (wall, cytoplasm, and vacuoles), both in hyphae and spores, was determined by energy-dispersive X-ray spectroscopy. In all treatments and fungal structures analysed, heavy metals accumulated mainly in the fungal cell wall and in the vacuoles, while minor changes in metal concentrations were detected in the cytoplasm. Incorporation of Zn into the fungus occurred during the first 8 h after metal addition with no subsequent accumulation. On the other hand, Cu steadily accumulated in the spore vacuoles over time, whereas Cd steadily accumulated in the hyphal vacuoles. These results suggest that binding of metals to the cell walls and compartmentalization in vacuoles may be essential mechanisms for metal detoxification.     

Actinide and metal toxicity to prospective bioremediation bacteria

Bacteria may be beneficial for alleviating actinide contaminant migration through processes such as bioaccumulation or metal reduction. However, sites with radioactive contamination often contain multiple additional contaminants, including metals and organic chelators. Bacteria-based bioremediation requires that the microorganism functions in the presence of the target contaminant, as well as other contaminants. Here, we evaluate the toxicity of actinides, metals and chelators to two different bacteria proposed for use in radionuclide bioremediation, Deinococcus radiodurans and Pseudomonas putida, and the toxicity of Pu(VI) to Shewanella putrefaciens. Growth of D. radiodurans was inhibited at metal concentrations ranging from 1.8 microM Cd(II) to 32 mM Fe(III). Growth of P. putida was inhibited at metal concentrations ranging from 50 microM Ni(II) to 240 mM Fe(III). Actinides inhibited growth at mM concentrations: chelated Pu(IV), U(VI) and Np(V) inhibit D. radiodurans growth at 5.2, 2.5 and 2.1 mM respectively. Chelated U(VI) inhibits P. putida growth at 1.7 mM, while 3.6 mM chelated Pu(IV) inhibits growth only slightly. Pu(VI) inhibits S. putrefaciens growth at 6 mM. These results indicate that actinide toxicity is primarily chemical (not radiological), and that radiation resistance does not ensure radionuclide tolerance. This study also shows that Pu is less toxic than U and that actinides are less toxic than other types of metals, which suggests that actinide toxicity will not impede bioremediation using naturally occurring bacteria.     

Heavy Metal Accumulation and Ecological Responses of Turfgrass to Rubbish Compost with EDTA Addition

Domestic rubbish compost is a complex-polluted system, containing multiple heavy metals,which limits its application. In the present study, Cr, Mn, Ni, Cu, Zn, Cd, and Pb accumulation and ecological responses of turfgrass to rubbish compost were investigated following the addition of EDTA. The results showed that the addition of EDTA significantly increased heavy metal accumulation in Lolium perenne L.and Festuca arundinacea L. Most heavy metal concentrations in L. perenne increased with increasing EDTA supply. The concentrations of Cr, Mn, Ni, Cu, and Cd in L. perenne were highest following the addition of 30 mmol/kg EDTA and the concentrations of Cr and Ni at this point reached concentrations of1914.17 and 521.25 μg/g, respectively. When the EDTA level was ＜ 20 mmol/kg, the accumulation of most heavy metals in F. arundinacea increased with increasing EDTA supply, but showed a tendency to decrease at EDTA concentrations ＞20 mmol/kg. The highest concentrations of Mn, Ni, Cu, and Zn in F.arundinacea reached 268.01, 110.94, 161.52 and 1 354.97 μg/g, respectively, following the addition of 20mmol/kg EDTA. The EDTA-induced increase in the accumulation of heavy metals in turfgrass was plantand metal-specific. L. perenne had a relatively high ability to accumulate Cr, Ni, and Zn. The highest Zn concentration was 2 979.58 μg/g and, following the addition of EDTA, the concentrations of the three metals were increased 26.23, 20.03, and 10.49-fold, respectively, compared with control. However, F. arundinacea showed a high ability to accumulate Cr, with the highest concentration (596.02 μg/g) seen following the addition of 30 mmol/kg EDTA; the concentration of Cr increased 15.51-fold compared with control. With EDTA addition, ecological responses of both turfgrass species showed that EDTA at concentrations ＜10mmol/kg increased seed germination and aboveground net primary production (ANP) of L. perenne and slightly inhibited those of F.arundinacea, but EDTA at concentrations ＞20 mmol/kg inhibited these parameters significantly for both species. Moreover, EDTA increased the chlorophyll and proline content at all concentrations tested. On the basis of the synthetic remediation index, the optimal EDTA concentration for turfgrass remediation of heavy metals in compost is approximately 10 mmol/kg.