Cranfield University, School of Water, Energy and Environment, Cranfield MK43 0AL, UK.
University of Copenhagen, Department of Plant and Environmental Sciences Microbial Ecology and Biotechnology, Denmark.
Sci Total Environ. 2019 Feb 10;650(Pt 2):2150-2163. doi: 10.1016/j.scitotenv.2018.09.339. Epub 2018 Sep 27.
A six-month laboratory scale study was carried out to investigate the effect of biochar and compost amendments on complex chemical mixtures of tar, heavy metals and metalloids in two genuine contaminated soils. An integrated approach, where organic and inorganic contaminants bioavailability and distribution changes, along with a range of microbiological indicators and ecotoxicological bioassays, was used to provide multiple lines of evidence to support the risk characterisation and assess the remediation end-point. Both compost and biochar amendment (p = 0.005) as well as incubation time (p = 0.001) significantly affected the total and bioavailable concentrations of the total petroleum hydrocarbons (TPH) in the two soils. Specifically, TPH concentration decreased by 46% and 30% in Soil 1 and Soil 2 amended with compost. These decreases were accompanied by a reduction of 78% (Soil 1) and 6% (Soil 2) of the bioavailable hydrocarbons and the most significant decrease was observed for the medium to long chain aliphatic compounds (EC) and medium molecular weight aromatic compounds (EC). Compost amendment enhanced the degradation of both the aliphatic and aromatic fractions in the two soils, while biochar contributed to lock the hydrocarbons in the contaminated soils. Neither compost nor biochar affected the distribution and behaviour of the heavy metals (HM) and metalloids in the different soil phases, suggesting that the co-presence of heavy metals and metalloids posed a low risk. Strong negative correlations were observed between the bioavailable hydrocarbon fractions and the ecotoxicological assays suggesting that when bioavailable concentrations decreased, the toxicity also decreased. This study showed that adopting a combined diagnostic approach can significantly help to identify optimal remediation strategies and contribute to change the over-conservative nature of the current risk assessments thus reducing the costs associated with remediation endpoint.
进行了为期六个月的实验室规模研究，以调查生物炭和堆肥改良剂对两种真实污染土壤中焦油、重金属和类金属复杂化学混合物的影响。采用综合方法，研究了有机和无机污染物生物有效性和分布变化，以及一系列微生物指标和生态毒理学生物测定，提供了多条证据来支持风险特征描述并评估修复终点。堆肥和生物炭改良（p=0.005）以及孵育时间（p=0.001）均显著影响两种土壤中总石油烃（TPH）的总量和生物可利用浓度。具体而言，在土壤 1 和土壤 2 中添加堆肥后，TPH 浓度分别降低了 46%和 30%。这些减少伴随着生物可利用烃的减少 78%（土壤 1）和 6%（土壤 2），并且在中链至长链脂肪族化合物（EC）和中分子量芳香族化合物（EC）中观察到最显著的减少。堆肥改良增强了两种土壤中脂肪族和芳香族部分的降解，而生物炭有助于将烃锁定在污染土壤中。堆肥和生物炭都没有影响重金属（HM）和类金属在不同土壤相中的分布和行为，这表明重金属和类金属的共存构成的风险较低。生物可利用烃分数与生态毒理学测定之间观察到强烈的负相关关系，表明当生物可利用浓度降低时，毒性也降低。本研究表明，采用综合诊断方法可以显著帮助确定最佳修复策略，并有助于改变当前风险评估的过度保守性质，从而降低与修复终点相关的成本。
