School of Resources and Environmental Science, Quanzhou Normal University, 362000, Quanzhou, PR China.
School of Resources and Environmental Science, Quanzhou Normal University, 362000, Quanzhou, PR China.
J Environ Manage. 2018 Jul 1;217:646-653. doi: 10.1016/j.jenvman.2018.04.007. Epub 2018 Apr 9.
Soil contamination is a serious problem with deleterious impacts on global sustainability. Readily available, economic, and highly effective technologies are therefore urgently needed for the rehabilitation of contaminated sites. In this study, two readily available materials prepared from bio-wastes, namely biochar and oyster shell waste, were evaluated as soil amendments to immobilize arsenic in a highly As-contaminated soil (up to 15,000 mgAs/kg). Both biochar and oyster shell waste can effectively reduce arsenic leachability in acid soils. After application of the amendments (2-4% addition, w/w), the exchangeable arsenic fraction decreased from 105.8 to 54.0 mg/kg. The application of 2%biochar +2% oyster shell waste most effectively reduced As levels in the column leaching test by reducing the arsenic concentration in the porewater by 62.3% compared with the treatment without amendments. Biochar and oyster shell waste also reduced soluble As(III) from 374.9 ± 18.8 μg/L to 185.9 ± 16.8 μg/L and As(V) from 119.8 ± 13.0 μg/L to 56.4 ± 2.6 μg/L at a pH value of 4-5. The treatment using 4% (w/w) amendments did not result in sufficient As immobilization in highly contaminated soils; high soluble arsenic concentrations (upto193.0 μg/L)were found in the soil leachate, particularly in the form of As(III), indicating a significant potential to pollute shallow groundwater aquifers. This study provides valuable insights into the use of cost-effective and readily available materials for soil remediation and investigates the mechanisms underlying arsenic immobilization in acidic soils.
土壤污染是一个严重的问题，对全球可持续性产生有害影响。因此，迫切需要可用于污染场地修复的、易得的、经济的和高效的技术。在这项研究中，评估了两种易得的生物废物衍生材料（生物炭和牡蛎壳废物）作为土壤改良剂，以固定高度砷污染土壤（高达 15,000mgAs/kg）中的砷。生物炭和牡蛎壳废物均可有效降低酸性土壤中砷的浸出率。添加改良剂（2-4%，w/w）后，可交换态砷从 105.8 降至 54.0mg/kg。与未添加改良剂的处理相比，2%生物炭+2%牡蛎壳废物的添加最有效地降低了柱淋滤试验中的砷含量，将孔水中的砷浓度降低了 62.3%。生物炭和牡蛎壳废物还将 pH 值为 4-5 时的可溶性 As(III)从 374.9±18.8μg/L 降低至 185.9±16.8μg/L，将 As(V)从 119.8±13.0μg/L 降低至 56.4±2.6μg/L。在高污染土壤中，4%（w/w）改良剂的处理并不能实现充分的砷固定；在土壤浸出液中发现高浓度可溶性砷（高达 193.0μg/L），特别是以 As(III)的形式存在，这表明对浅层地下水含水层造成污染的潜力很大。本研究为利用经济且易得的材料进行土壤修复提供了有价值的见解，并研究了酸性土壤中砷固定的机制。
