Norwegian Institute for Water Research, Gaustadalléen 21, NO-0349 Oslo, Norway; University of Agder, Center for Coastal Research, NO-4604 Kristiansand, Norway.
Department of Ecology, Environment and Plant Sciences (DEEP), Stockholm University, 106 91 Stockholm, Sweden.
Sci Total Environ. 2021 Jul 1;776:145971. doi: 10.1016/j.scitotenv.2021.145971. Epub 2021 Feb 19.
The Grenland fjords in Norway have a long history of contamination by large emissions of dioxins and mercury. As a possible sediment remediation method in situ, thin-layer capping with powdered activated carbon (AC) mixed with clay was applied at two test sites at 30 m and 95 m depth in the Grenland fjords. This study presents long-term effects of the AC treatment on the benthic community structure, i.e. nine years after capping. Capping with AC significantly reduced the number of species, their abundance and biomass at the two test sites, compared to uncapped reference sites. At the more shallow site, the dominant brittle star species Amphiura filiformis disappeared shortly after capping and did not re-establish nine years after capping. At the deeper site, the AC treatment also caused long-lasting negative effects on the benthic community, but some recovery was observed after nine years. Ecological indices used to assess environmental status did not capture the impaired benthic communities caused by the capping. The present study is the first documentation of negative effects of powdered AC on marine benthic communities on a decadal scale. Our results show that the benefits of reduced contaminant bioavailability from capping with AC should be carefully weighed against the cost of long-term detrimental effects on the benthic community. More research is needed to develop a thin-layer capping material that is efficient at sequestering contaminants without being harmful to benthic species.
挪威的格陵兰峡湾长期受到二恶英和汞的大量排放污染。作为一种原位沉积物修复方法，在格陵兰峡湾的 30 米和 95 米深处的两个试验点应用了薄层覆盖法，即将粉状活性炭（AC）与粘土混合。本研究介绍了 AC 处理对底栖生物群落结构的长期影响，即在覆盖 9 年后。与未覆盖的对照点相比，AC 覆盖显著降低了两个试验点的物种数量、丰度和生物量。在较浅的地点，覆盖后不久，优势脆星物种 Amphiura filiformis 消失，9 年后仍未恢复。在较深的地点，AC 处理也对底栖生物群落造成了持久的负面影响，但 9 年后观察到了一些恢复。用于评估环境状况的生态指数没有捕捉到覆盖造成的受损底栖生物群落。本研究首次记录了粉状 AC 对海洋底栖生物群落的负面影响，其持续时间长达十年。我们的研究结果表明，在权衡使用 AC 覆盖减少污染物生物有效性的好处时，应仔细考虑其对底栖生物群落的长期不利影响。需要进一步研究开发一种薄层覆盖材料，既能有效隔离污染物，又不对底栖物种造成危害。
