Paleolimnological assessment of the controls on metal mobility in Nova Scotia

砷(As)是加拿大沿海地区普遍存在的一种环境毒素和致癌金属。地表水和地下水系统对砷的富集性非常敏感。砷的生物积累是一个令人严重关切的问题。在新斯科舍省，已有地下水来源砷中毒的报告，土壤和水生沉积物中砷浓度升高的情况很常见。砷有许多天然的地方和区域来源；采矿和开发都对类金属进行了浓缩和动员。砷在环境介质中的迁移是复杂的，影响砷在淡水和咸水地表水系统中的保留和迁移的因素知之甚少。这项研究的重点是利用湖泊沉积物档案(古湖沼学)更好地了解流域尺度的景观干扰(采矿、开发)如何影响加拿大新斯科舍省各种环境中砷的迁移和保留。研究将在哈利法克斯地区市政当局(HRM)、布雷顿角地区市政当局(CBRM)和坎伯兰沼泽地区(新斯科舍省-新不伦瑞克边境地区)进行。稳定同位素(C，N)、块状沉积物地球化学(电感耦合等离子体质谱(ICPMS)、X射线荧光光谱(XRF)、X射线衍射谱(XRD))和一套结合放射性测年(14C和210Pb)的非生物替代物将被应用于重力取心获得的湖泊沉积物档案，以重建500年的沉积记录。在NS的生物代理研究确定了地表水系统中的重要环境应激源(例如，pH、T、EH、TP)，将用于预测环境变化如何已经和将如何影响湖泊沉积物中的砷的移动性和滞留。正在为HRM和CBRM开发地下水模型，这些模型将有助于预测历史流域干扰与湖泊沉积物总体地球化学之间的关系。所有地点景观扰动的300年历史记录将使湖泊沉积物档案与历史记录相结合，以更好地了解扰动、水柱化学和气候变化对金属迁移和保留的相对重要性。此外，还将探讨湖泊沉积物组成和湖泊水柱氧化还原条件在金属固定和迁移中的作用。这项研究是合作的，并将与已经在进行的生物积累和毒理学研究相结合。拟议的研究将制定战略，以促进有效的分水岭管理，并帮助确定增加地下水中砷含量升高风险的条件以及水系统中砷的生物可获得性和流动性。这项研究所需的实地和实验室技术将培训高素质的个人，而且可以转让，而且相对便宜；向公共和私营部门转让技术将是这项研究的一个重要组成部分。

Arsenic (As) is a pervasive environmental toxin and carcinogenic metalloid in Maritime Canada. Surface and groundwater systems are highly susceptible to arsenic enrichment. Bioaccumulation of arsenic is a significant concern. In Nova Scotia arsenic poisoning from groundwater sources has been reported and elevated concentrations in soils and aquatic sediments are common. There are many natural local and regional sources of arsenic; mining and development have both concentrated and mobilized the metalloid. The mobility of arsenic among environmental media is complex, the factors affecting the retention and mobility of arsenic in fresh and brackish surface water systems are poorly understood. This research proposal focuses on the use of lake sediment archives (paleolimnology) to better understand how watershed-scale landscape disturbance (mining, development) influences the mobility and retention of arsenic in a variety of environments in Nova Scotia, Canada.Research will take place in Halifax Regional Municipality (HRM), Cape Breton Regional Municipality (CBRM) and the Cumberland Marsh Region (Nova Scotia-New Brunswick border region). Stable isotopes (C, N), bulk sediment geochemistry (ICP-MS, XRF, XRD), and a suite of abiotic proxies coupled with radiometric dating (14C and 210Pb) will be applied to lake sediment archives obtained by gravity coring to reconstruct 500-year sedimentary records. Bioproxy research in NS that identified the significant environmental stressors (e.g. pH, T, EH, TP) in surface water systems will be applied to predict how environmental change has and will influence arsenic mobility and retention in lake sediments. Groundwater models are being developed for HRM and CBRM that will be used to help predict the relationship between historical watershed disturbance and the bulk geochemistry of lake sediments. A >300 year historical record of landscape disturbance at all sites will enable the integration of the lake sediment archive with historical records to better understand the relative importance of disturbance, water column chemistry and climate variability on metal mobility and retention. As well, the role of lake sediment composition and lake water column redox conditions in metal sequestration and mobility will be explored.This research is collaborative and will be integrated with bioaccumulation and toxicology research already in progress. The proposed research will develop strategies that will facilitate effective watershed management and help determine conditions that increase the risk of elevated arsenic in groundwater and arsenic bioavailability and mobility in aquatic systems. The field and laboratory techniques required in this research will train highly qualified individuals and are transferrable and relatively inexpensive; technology transfer to both the public and private sector will be an important component of this research.