Meers E, Ruttens A, Geebelen W, Vangronsveld J, Samson R, Vanbroekhoven K, Vandegehuchte M, Diels L, Tack F M G
Department of Applied Analytical and Physical Chemistry, Laboratory of Analytical Chemistry and Applied Ecochemistry, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
Environ Monit Assess. 2006 Sep;120(1-3):243-67. doi: 10.1007/s10661-005-9059-7. Epub 2006 Aug 3.
In recent years, awareness has risen that the total soil content of pollutants by itself does not suffice to fully assess the potential ecotoxicological risks involved. Chemical analysis will require to be complemented with biological assays in a multidisciplinary approach towards site specific ecological risk assessment (SS-ERA). This paper evaluates the potential use of the plants' antioxidant response to metal-induced oxidative stress to provide a sensitive biological assay in SS-ERA. To this end, plants of Phaseolus vulgaris were grown for two weeks on 15 soils varying in contamination level. Morphological parameters and enzymatic plant responses were measured upon harvest. Foliar concentrations of the (heavy) metals Al, Cu, Cd, Cr, Fe, Mn, Ni, Pb, Zn were also determined. Metal mobility in the soil was further assessed by determining soil solution and NH4OAc extractable levels. In general more significant correlations were observed between plant responses and foliar metal concentrations or exchangeable/soluble levels than between plant responses and the total soil content. The study demonstrates the potential use of the plants' antioxidant defence mechanisms to assess substrate phytotoxicity for application in SS-ERA protocols. However, the system, based on calculation of a soil Phytotoxicity Index (PI), will require adaptation and fine-tuning to meet the specific needs for this type of environmental monitoring. Large variation was observed in phytotoxicity classification based on the various test parameters. The thresholds for classification of the various morphological and enzymatic response parameters may require adaptation according to parameter stress sensitivity in order to decrease the observed variation. The use of partial PI's (leaves and roots separately) may in addition increase the sensitivity of the system since some metals show specific effects in one of both organs only. Loss of biological functionality of enzymes, as was observed for ICDH in one of the more strongly contaminated soils, may also be recognized as an additional stress symptom when assigning phytotoxicity classification, whereas the current system only considers increasing enzymatic capacities. Other easily distinguishable parameters, which could be added to the current indexation are: failure to germinate and the incapacity to develop roots in the toxic substrate. Additional research will be required to determine the possible application range of soil properties for this biological assay and to further improve its performance in SS-ERA.
近年来，人们越来越意识到，仅土壤中污染物的总量不足以全面评估所涉及的潜在生态毒理学风险。在针对特定场地生态风险评估（SS-ERA）的多学科方法中，化学分析需要辅以生物测定。本文评估了植物对金属诱导的氧化应激的抗氧化反应在SS-ERA中作为一种灵敏生物测定方法的潜在用途。为此，将菜豆植株在15种污染程度不同的土壤上种植两周。收获时测量形态学参数和植物酶促反应。还测定了叶片中（重）金属铝、铜、镉、铬、铁、锰、镍、铅、锌的浓度。通过测定土壤溶液和醋酸铵可提取水平进一步评估土壤中金属的迁移性。一般来说，与植物反应和叶片金属浓度或可交换/可溶性水平之间的相关性，比植物反应与土壤总含量之间的相关性更为显著。该研究证明了植物抗氧化防御机制在评估底物植物毒性以应用于SS-ERA方案中的潜在用途。然而，基于土壤植物毒性指数（PI）计算的系统需要进行调整和微调，以满足此类环境监测的特定需求。基于各种测试参数的植物毒性分类存在很大差异。各种形态学和酶促反应参数的分类阈值可能需要根据参数应激敏感性进行调整，以减少观察到的差异。使用部分PI（分别针对叶片和根部）可能还会提高系统的敏感性，因为一些金属仅在两个器官之一中表现出特定影响。在一种污染较重的土壤中观察到的异柠檬酸脱氢酶（ICDH）酶生物功能丧失，在确定植物毒性分类时也可被视为一种额外的应激症状，而当前系统仅考虑酶活性的增加。可以添加到当前指数中的其他易于区分的参数包括：在有毒底物中不能发芽和不能生根。需要进一步研究以确定该生物测定方法中土壤性质的可能应用范围，并进一步提高其在SS-ERA中的性能。
