Department of Physical Geography, School of Earth Sciences, Shahid Beheshti University, Tehran, 1983969411, Iran.
Sustainable Agriculture Sciences Department, Rothamsted Research, North Wyke, Okehampton, EX20 2SB, UK.
Environ Sci Pollut Res Int. 2019 Sep;26(27):28401-28414. doi: 10.1007/s11356-019-06024-x. Epub 2019 Aug 2.
Transport and deposition of fine-grained sediment, a pervasive nonpoint source pollutant, cause deleterious off-site impacts for water quality and aquatic ecosystems. Sediment fingerprinting provides one means of identifying the spatial sources of mobilised sediment delivered to fluvial systems in order to help target sediment control strategies and uptake of such source tracing procedures has been steadily increasing. Nonetheless, there remains a need to continue testing and comparing different composite signatures for source discrimination including the incorporation of physically grounded information relevant to erosion patterns. Accordingly, the objective of this study was to compare the discrimination and apportionment of sub-basin spatial suspended sediment sources in a mountainous basin in northern Tehran, Iran, using composite signatures comprising conventional geochemical tracers combined with lithological weathering indices or only the former. The list of conventional geochemical properties comprised Al, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, Sr, Ti, and Zn whilst three weathering indices were included: the chemical index of alteration (CIA), the weathering index of Parker (WIP), and the indicator of recycling (IR) which were all calculated based on elemental oxides. Using a composite signature combining conventional geochemical tracers and one weathering index (IR), the relative contributions from the sub-basin spatial sources were estimated at 1 (Imamzadeh Davood; 1.4%), 2 (Taloon; 13.4%), 3 (Soleghan; 35.9%), and 4 (Keshar; 48.4%) compared with corresponding respective estimates of 0.7%, 45.5%, 40.2%, and 13.3% using conventional geochemical tracers alone. Wald-Wolfowitz Runs test pairwise comparisons of the posterior distributions of predicted source proportions generated using the two different composite signatures confirmed statistically significant differences. These differing proportions demonstrated the sensitivity of predicted source apportionment to the inclusion or exclusion of a weathering index providing information reflecting the relative coverage of more erodible lithological formations in each of the sub-basins (32.7% sub-basin 1, 53.6% sub-basin 2, 58.5% sub-basin 3, and 63.2% sub-basin 4). The outputs of this study will be used to target sediment mitigation strategies.
细颗粒泥沙的输运和沉积是一种普遍的非点源污染物，会对水质和水生生态系统造成有害的场外影响。泥沙示踪技术提供了一种识别输移到河流系统中可移动泥沙的空间来源的方法，有助于确定泥沙控制策略，并且这种源追踪方法的应用一直在稳步增加。然而，仍需要继续测试和比较不同的复合示踪剂，以进行源区分，包括纳入与侵蚀模式相关的物理基础信息。因此，本研究的目的是比较使用包含常规地球化学示踪剂与岩石风化指数的复合示踪剂或仅使用前者，对伊朗德黑兰北部山区流域子流域悬浮泥沙源的区分和分配。常规地球化学性质列表包括 Al、Ca、Cu、Fe、K、Mg、Mn、Na、Ni、Sr、Ti 和 Zn，同时还包括三个风化指数：化学蚀变指数（CIA）、帕克风化指数（WIP）和再循环指标（IR），这些指数均基于元素氧化物计算。使用包含常规地球化学示踪剂和一个风化指数（IR）的复合示踪剂，估计子流域空间来源的相对贡献分别为 1（Imamzadeh Davood；1.4%）、2（Taloon；13.4%）、3（Soleghan；35.9%）和 4（Keshar；48.4%），而仅使用常规地球化学示踪剂的相应估计值分别为 0.7%、45.5%、40.2%和 13.3%。沃尔德-沃尔夫茨运行检验两种不同复合示踪剂生成的预测源比例后验分布的两两比较，证实了存在统计学上的显著差异。这些不同的比例表明，预测源分配对风化指数的包含或排除很敏感，为每个子流域中更易侵蚀岩石地层的相对覆盖范围提供了信息（32.7%子流域 1、53.6%子流域 2、58.5%子流域 3 和 63.2%子流域 4）。本研究的结果将用于确定泥沙缓解策略的目标。
