Cho Yeo-Myoung, Smithenry Dennis W, Ghosh Upal, Kennedy Alan J, Millward Rod N, Bridges Todd S, Luthy Richard G
Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA.
Mar Environ Res. 2007 Dec;64(5):541-55. doi: 10.1016/j.marenvres.2007.04.006. Epub 2007 May 10.
Previous laboratory studies have shown reductions in PCB bioavailability for sediments amended with activated carbon (AC). Here we report results on a preliminary pilot-scale study to assess challenges in scaling-up for field deployment and monitoring. The goals of the preliminary pilot-scale study at Hunters Point Shipyard (San Francisco, USA) were to (1) test the capabilities of a large-scale mixing device for incorporating AC into sediment, (2) develop and evaluate our field assessment techniques, and (3) compare reductions in PCB bioavailability found in the laboratory with well-mixed systems to those observed in the field with one-time-mixed systems. In this study we successfully used a large-scale device to mix 500kg of AC into a 34.4m(2) plot to a depth of 1ft, a depth that includes the majority of the biologically active zone. Our results indicate that after 7 months of AC-sediment contact in the field, the 28-day PCB bioaccumulation for the bent-nosed clam, Macoma nasuta, field-deployed to this AC-amended sediment was approximately half of the bioaccumulation resulting from exposure to untreated sediment. Similar PCB bioaccumulation reductions were found in laboratory bioassays conducted on both the bivalve, M. nasuta and the estuarine amphipod, Leptocheirus plumulosus, using sediment collected from the treated and untreated field plots one year after the AC amendment occurred. To further understand the long-term effectiveness of AC as an in situ treatment strategy for PCB-contaminated sediments under field conditions, a 3-year comprehensive study is currently underway at Hunters Point that will compare the effectiveness of two large-scale mixing devices and include both unmixed and mixed-only control plots.
先前的实验室研究表明，用活性炭（AC）改良的沉积物中多氯联苯的生物可利用性会降低。在此，我们报告一项初步中试规模研究的结果，以评估扩大规模用于现场部署和监测时所面临的挑战。美国旧金山猎人角造船厂的初步中试规模研究目标是：（1）测试一种将活性炭混入沉积物的大型混合装置的能力；（2）开发并评估我们的现场评估技术；（3）比较实验室中充分混合系统里多氯联苯生物可利用性的降低情况与现场一次性混合系统中观察到的情况。在本研究中，我们成功使用一种大型装置将500千克活性炭混入一块34.4平方米的区域，深度达1英尺，该深度涵盖了大部分生物活性区。我们的结果表明，在现场活性炭与沉积物接触7个月后，实地部署到这种经活性炭改良沉积物中的弯鼻蛤（Macoma nasuta）的28天多氯联苯生物累积量约为接触未处理沉积物所导致生物累积量的一半。在活性炭改良一年后，使用从处理和未处理现场地块采集的沉积物，对双壳类动物弯鼻蛤和河口双足类动物细角长臂虾进行实验室生物测定，也发现了类似的多氯联苯生物累积量降低情况。为了进一步了解在现场条件下活性炭作为多氯联苯污染沉积物原位处理策略的长期有效性，猎人角目前正在进行一项为期3年的综合研究，该研究将比较两种大型混合装置的有效性，并包括未混合和仅混合的对照地块。
