Delgadillo Víctor, Verdejo José, Mondaca Pedro, Verdugo Gabriela, Gaete Hernán, Hodson Mark E, Neaman Alexander
Escuela de Agronomía, Pontificia Universidad Católica de Valparaíso, Quillota, Chile.
Escuela de Ingeniería en Medioambiente, Universidad de Valparaíso, Valparaíso, Chile.
Ecotoxicol Environ Saf. 2017 Jun;140:230-234. doi: 10.1016/j.ecoenv.2017.02.038. Epub 2017 Mar 8.
Use of avoidance tests is a quick and cost-effective method of assessing contaminants in soils. One option for assessing earthworm avoidance behavior is a two-section test, which consists of earthworms being given the choice to move between a test soil and a control substrate. For ecological relevance, tested soils should be field-contaminated soils. For practical reasons, artificial soils are commonly used as the control substrate. Interpretation of the test results compromised when the test soil and the artificial substrate differ in their physico-chemical properties other than just contaminants. In this study we identified the physico-chemical properties that influence avoidance response and evaluated the usefulness of adjusting these in the control substrate in order to isolate metal-driven avoidance of field soils by earthworms. A standardized two-section avoidance test with Eisenia fetida was performed on 52 uncontaminated and contaminated (Cu >155mgkg, As >19mgkg) agricultural soils from the Aconcagua River basin and the Puchuncaví Valley in Chile. Regression analysis indicated that the avoidance response was determined by soil organic matter (OM), electrical conductivity (EC) and total soil Cu. Organic matter content of the artificial substrate was altered by peat additions and EC by NaCl so that these properties matched those of the field soils. The resultant EC for avoidance (indicative of soils of "limited habitat") was 433mg Cu kg (339 - 528mgkg 95% confidence intervals). The earthworm avoidance test can be used to assess metal toxicity in field-contaminated soils by adjusting physico-chemical properties (OM and EC) of the artificial control substrate in order to mimic those of the field-collected soil.
使用回避测试是评估土壤中污染物的一种快速且经济高效的方法。评估蚯蚓回避行为的一种方法是两段式测试，即让蚯蚓在测试土壤和对照基质之间进行移动选择。出于生态相关性的考虑，测试土壤应为现场受污染土壤。出于实际原因，人工土壤通常用作对照基质。当测试土壤和人工基质除污染物外的物理化学性质存在差异时，会影响对测试结果的解释。在本研究中，我们确定了影响回避反应的物理化学性质，并评估了在对照基质中调整这些性质以分离蚯蚓对田间土壤中金属驱动的回避行为的有效性。对来自智利阿空加瓜河流域和普琼卡维山谷的52份未受污染和受污染（铜>155mg/kg，砷>19mg/kg）的农业土壤进行了标准化的两段式回避测试，以赤子爱胜蚓为测试对象。回归分析表明，回避反应由土壤有机质（OM）、电导率（EC）和土壤总铜含量决定。通过添加泥炭改变人工基质的有机质含量，通过添加氯化钠改变电导率，以使这些性质与田间土壤相匹配。由此得出的回避电导率（指示“有限栖息地”的土壤）为433mg铜/kg（95%置信区间为339 - 528mg/kg）。通过调整人工对照基质的物理化学性质（OM和EC）以模拟田间采集土壤的性质，蚯蚓回避测试可用于评估现场受污染土壤中的金属毒性。
