Gomes Pattiyage I A, Asaeda Takashi
Department of Environmental Science and Technology, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8770, Japan.
J Hazard Mater. 2009 Jul 30;166(2-3):1332-8. doi: 10.1016/j.jhazmat.2008.12.055. Epub 2008 Dec 14.
This article discusses the applicability of the Charophyte, Nitella pseudoflabellata in the remediation of Cr (VI) contaminated waters at different calcifying potentials. Its growth was found to be positively correlated with Ca in water (CaW), but marginally significant in the presence of Cr (VI) in water (CrW). High CaW resulted in calcite encrustation on the plant cell wall. CaW was found to be aiding Cr (VI) fixation in the long run, as this correlated positively with both CaW and CrW. However, Ca interfered with passive Cr (VI) accumulation in live plant matter at low CrW concentrations (<or=0.2mg/L). Biosorption by dead plant matter seemed to be the major mechanism as the dead plant organs contained >1mg/g Cr dry weight of plant. Cr (VI) concentrations greater than 0.4 mg/L were too toxic, showing maximum quantum efficiency of PSII photochemistry (F(v)/F(m)) values<0.63. The opposite was noticed (F(v)/F(m)>0.76) when Cr (VI) was less than 0.2mg/L. Elongation curve patterns based on shoot lengths showed similar scenarios. In all cases high CaW units with calcite encrustation found to be least affected by Cr (VI) toxicity. Optimum remediation was obtained using a combination of high Ca and Cr (VI) in the case of passive (short-term) operation and low Ca and Cr (VI) for active (long-term) operation. Under the passive scenario, plants accumulated above 1.2mg/g Cr dry weight whereas in the active case, accumulation was 0.8 mg/g Cr dry weight. We conclude that Nitella-mediated Cr (VI) remediation is a promising technique within the range and conditions investigated.
本文讨论了轮藻属的拟扇形丽藻在不同钙化潜力下对六价铬污染水体的修复适用性。研究发现其生长与水中的钙（CaW）呈正相关，但在水中存在六价铬（CrW）时相关性较弱。高CaW导致植物细胞壁上有方解石结壳。从长远来看，CaW有助于固定六价铬，因为它与CaW和CrW均呈正相关。然而，在低CrW浓度（≤0.2mg/L）时，Ca会干扰活体植物物质中六价铬的被动积累。死植物物质的生物吸附似乎是主要机制，因为死植物器官中铬的干重含量>1mg/g。六价铬浓度大于0.4mg/L时毒性过大，导致PSII光化学最大量子效率（F(v)/F(m)）值<0.63。当六价铬浓度小于0.2mg/L时则出现相反情况（F(v)/F(m)>0.76）。基于茎长的伸长曲线模式显示了类似情况。在所有情况下，发现有碳酸钙结壳的高CaW单位受六价铬毒性影响最小。在被动（短期）操作中，使用高钙和六价铬的组合可获得最佳修复效果，而在主动（长期）操作中则使用低钙和六价铬。在被动情况下，植物积累的铬干重超过1.2mg/g，而在主动情况下，积累量为0.8mg/g铬干重。我们得出结论，在所研究的范围和条件下，拟扇形丽藻介导的六价铬修复是一项有前景的技术。
