Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, 1360 Barrington St, Halifax, Nova Scotia, B3H 4R2, Canada.
Department of Earth & Environmental Science, Acadia University, 12 University Ave, Wolfville, Nova Scotia, B4P 2R6, Canada.
Environ Sci Pollut Res Int. 2021 Oct;28(37):51342-51355. doi: 10.1007/s11356-021-14212-x. Epub 2021 May 12.
The paleolimnological method was used to decouple geogenic and anthropogenic metal (loids) contributions in a sediment stabilization basin (Boat Harbour) located in Nova Scotia, Canada. Boat Harbour has been impacted by industrial effluents discharged by a bleached kraft pulp mill (1967 to 2019) and a chlor-alkali plant (1971 to 1992). The former estuary now contains >577,000 m of unconsolidated sediment, impacted by inorganic and organic contaminants, including metal[loid]s, polycyclic aromatic hydrocarbons and polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans. Previous studies indicated significant knowledge gaps in our understanding of the spatial, stratigraphic, and temporal variation of sediment contamination. Twenty-five lakebed sediment gravity cores were obtained between 2016 and 2019 to determine spatiotemporal distribution of sediment As, Cu, Pb, and Zn concentrations which consistently exceeded guidelines for aquatic sediments. Results demonstrate there is no distinct spatial trend in metal concentrations despite point source effluent inputs. High and variable concentrations of Cu and Zn in contaminated sediment likely represent a combination of cation capture by highly organic sediment and influence of pulp mill on lakebed sediment chemistry. Elevated Pb in contaminated sediment is the result of atmospheric deposition from combustion of fossil fuels and bioaccumulation in effluent feedstock. Average sedimentation rate (1 cm every 3 years) is high compared to a nearby freshwater lake and is enhanced by increased nutrient loading and more productive water column conditions associated with effluent introduction. Temporal trends indicate significantly higher concentrations of Zn and Cu in top sediment samples consistent with changes in effluent treatment procedures as well as composition of effluent solids. Comparison of geochemistry of effluent influenced sediment and pre-effluent substate sediment at Boat Harbour to freshwater and marine reference was required to understand the degree to which geogenic and anthropogenic sources of metal(loids) have influenced effluent chemistry. This study demonstrates that undisturbed, time transgressive samples from both impacted sites and reference sites combined with non-destructive, rapid, small sample analytical techniques such as X-ray fluorescence, provide an accurate assessment of sediment metal contaminant distribution, data required to guide remediation and environmental effects monitoring and compliance.
该研究采用古湖沼学方法，将加拿大新斯科舍省的 Boat Harbour 沉积物稳定盆地中的自然成因和人为成因金属（类金属）贡献进行了区分。该盆地受到了 1967 年至 2019 年期间的漂白白硫酸盐浆厂和 1971 年至 1992 年期间的氯碱厂排放的工业废水的影响。该前河口现在含有超过 577000 立方米的未固结沉积物，受到无机和有机污染物的影响，包括金属（类金属）、多环芳烃和多氯代二苯并对二恶英、多氯代二苯并呋喃。先前的研究表明，我们对沉积物污染的空间、地层和时间变化的认识存在重大知识差距。2016 年至 2019 年期间，共获得了 25 个湖底沉积物重力岩芯，以确定沉积物砷、铜、铅和锌浓度的时空分布情况，这些浓度一直超过水生沉积物的指导值。结果表明，尽管存在点源废水输入，但金属浓度没有明显的空间趋势。受污染沉积物中高浓度且变化的铜和锌含量可能是高度有机沉积物中阳离子捕获以及浆厂对湖底沉积物化学性质影响的综合结果。受污染沉积物中高浓度的铅是化石燃料燃烧产生的大气沉降和废水中原料生物累积的结果。与附近的淡水湖相比，平均沉积速率（每 3 年 1 厘米）较高，并且由于营养物质负荷增加和与废水引入相关的更具生产力的水柱条件，沉积速率进一步提高。时间趋势表明，与废水处理程序的变化以及废水固体的组成相一致，顶部沉积物样品中的锌和铜浓度显著更高。为了了解自然成因和人为成因金属（类金属）来源对废水化学性质的影响程度，需要将 Boat Harbour 的受废水影响的沉积物和亚州沉积物的地球化学性质与淡水和海洋参比进行比较。该研究表明，结合未受干扰的、时间推移的受影响和参考地点的样本以及非破坏性的、快速的、小样本分析技术，如 X 射线荧光，为沉积物金属污染物分布提供了准确的评估，这是指导补救和环境影响监测以及合规性所需的数据。
