Department of Ecology, Environment and Plant Sciences (DEEP), Stockholm University, 106 91 Stockholm, Sweden.
Department of Ecology, Environment and Plant Sciences (DEEP), Stockholm University, 106 91 Stockholm, Sweden.
Sci Total Environ. 2024 Oct 10;946:174263. doi: 10.1016/j.scitotenv.2024.174263. Epub 2024 Jun 25.
Sediments polluted with hydrophobic organic contaminants (HOCs) and metals can pose environmental risks, yet effective remediation remains a challenge. We investigated a new composite sorbent comprising granular activated carbon (GAC) and a calcium-silicate (Polonite®, PO) for thin-layer capping of polluted sediment, with the aim to sequester both HOCs and metals. Box cores were collected in polluted Oskarshamn harbor, Sweden, and the sediments were treated with GAC and/or Polonite in a 10-week mesocosm study to measure endpoints ranging from contaminant immobilization to ecological side effects on native fauna and biogeochemical processes. The GAC particle size was 300-500 μm to reduce negative effects on benthic fauna (by being non-ingestible) and of biogenic origin (coconut) to have a small carbon footprint compared with traditional fossil ACs. The calcium-silicate was a fine-grained industrial by-product used to target metals and as a carrier for GAC to improve the cap integrity. GAC decreased the uptake of dioxins (PCDD/Fs) in the bivalve Macoma balthica by 47 % and the in vitro bioavailability of PCB by 40 %. The composite cap of GAC + Polonite decreased sediment-to-water release of Pb < Cu < Ni < Zn < Cd by 42-98 % (lowest to highest decrease) and bioaccumulation of Cd < Zn < Cu in the worm Hediste diversicolor by 50-65 %. Additionally, in vitro bioavailability of Pb < Cu < Zn, measured using digestive fluid extraction, decreased by 43-83 %. GAC showed no adverse effects on benthic fauna while Polonite caused short-term adverse effects on fauna diversity and abundance, partly due to its cohesiveness, which, in turn, can improve the cap integrity in situ. Fauna later recovered and bioturbated the cap. Both sorbents influenced biogeochemical processes; GAC sorbed ammonium, Polonite decreased respiration, and both sorbents reduced denitrification. In conclusion, the side effects were relatively mild, and the cap decreased the release and bioavailability of both HOCs and metals effectively, thus offering a promising sustainable and cost-effective solution to remediating polluted sediments.
被疏水性有机污染物 (HOCs) 和金属污染的沉积物可能构成环境风险，但有效的修复仍然是一个挑战。我们研究了一种由颗粒状活性炭 (GAC) 和钙硅酸盐 (Polonite®, PO) 组成的新型复合吸附剂，用于污染沉积物的薄层覆盖，旨在固定 HOCs 和金属。在瑞典受污染的奥斯卡港采集了箱芯，并在为期 10 周的中观研究中用 GAC 和/或 Polonite 处理沉积物，以测量从污染物固定到对本地动物群的生态副作用和生物地球化学过程的各种终点。GAC 颗粒大小为 300-500μm，以减少对底栖动物的负面影响（因为不可食用）和生物成因（椰子），与传统的化石 AC 相比，碳足迹较小。钙硅酸盐是一种细颗粒的工业副产品，用于靶向金属，并作为 GAC 的载体，以提高帽的完整性。GAC 使双壳类动物 Macoma balthica 对二恶英（PCDD/Fs）的吸收减少了 47%，对 PCB 的体外生物可利用性减少了 40%。GAC+Polonite 复合帽使 Pb<Cu<Ni<Zn<Cd 从沉积物向水中的释放减少了 42-98%（降低幅度最低到最高），Hediste diversicolor 蠕虫体内 Cd<Zn<Cu 的生物累积减少了 50-65%。此外，使用消化液提取法测量的 Pb<Cu<Zn 的体外生物可利用性降低了 43-83%。GAC 对底栖动物没有不良影响，而 Polonite 则对动物群的多样性和丰度产生了短期的不良影响，部分原因是其粘性，这反过来又可以改善原位帽的完整性。动物群后来恢复并搅动了帽。两种吸附剂都影响了生物地球化学过程；GAC 吸附了铵，Polonite 降低了呼吸作用，两者都减少了反硝化作用。总之，副作用相对较轻，帽子有效地减少了 HOCs 和金属的释放和生物可利用性，因此为修复污染沉积物提供了一种有前途的可持续且具有成本效益的解决方案。
