Tomaszewski Jeanne E, Werner David, Luthy Richard G
Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305-4020, USA.
Environ Toxicol Chem. 2007 Oct;26(10):2143-50. doi: 10.1897/07-179R.1.
Pesticide formulators formerly operating at Lauritzen Channel, a portion of San Francisco Bay near Richmond (CA, USA), caused contamination of sediment with dichlorodiphenyltrichloroethane (DDT). The present study evaluated the distribution of residual DDT in channel sediment six years following extensive remedial dredging. High DDT concentrations (up to 252 mg/ kg) were found in Young Bay Mud sampled across the channel. Particle analyses showed most of the contamination is contained in the clay/silt sediment fraction, and desorption tests showed that availability is greater for DDT metabolites than parent DDT. The present study examined the feasibility of using activated carbon amendment to sequester DDT from sediment, including an evaluation of reactivated carbon as a less costly alternative to virgin activated carbons. Treatment success of activated carbon amendment to sediment collected from Lauritzen Channel was measured by reductions in aqueous equilibrium concentrations and uptake in semipermeable membrane devices (SPMDs). Four different activated carbons were tested and, after one month of treatment with 3.2 weight % carbon, DDT aqueous equilibrium concentrations were reduced up to 83% and SPMD uptake was reduced up to 91%. Reactivated carbon was comparable with virgin carbons in all tests. Reduction in SPMD uptake of DDT by treatment with 3.2% reactivated carbon increased to 99% after 26 months of treatment. The effectiveness of activated carbon was dependent on the type, size, dose, and contact time. The results show the potential usefulness of activated carbon amendment as a follow-up remedial technology for management of residuals after dredging contaminated sediment.
农药配方师曾在美国加利福尼亚州里士满附近旧金山湾的一部分——劳里岑海峡作业，导致二氯二苯三氯乙烷（DDT）污染沉积物。本研究评估了大规模修复疏浚六年后海峡沉积物中残留DDT的分布情况。在海峡各处采集的扬湾泥中发现了高浓度的DDT（高达252毫克/千克）。颗粒分析表明，大部分污染物存在于黏土/粉砂沉积物部分，解吸试验表明，DDT代谢物的可利用性高于母体DDT。本研究考察了使用活性炭改良剂从沉积物中螯合DDT的可行性，包括评估再生活性炭作为原生活性炭成本较低的替代品。通过降低水相平衡浓度和半透膜装置（SPMDs）中的吸收量来衡量活性炭改良剂对从劳里岑海峡采集的沉积物的处理效果。测试了四种不同的活性炭，在用3.2重量%的碳处理一个月后，DDT水相平衡浓度降低了83%，SPMD吸收量降低了91%。在所有测试中，再生活性炭与原生活性炭相当。用3.2%再生活性炭处理26个月后，SPMD对DDT的吸收量降低至99%。活性炭的有效性取决于类型、尺寸、剂量和接触时间。结果表明，活性炭改良作为疏浚受污染沉积物后管理残留污染物的后续修复技术具有潜在的实用性。
