The transport and accumulation processes of geochemical tracers in environmental compartments
- Publication Type:
- Thesis
- Issue Date:
- 2021
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The ubiquitous geochemical tracers tend to persistently transport and accumulate in different environmental compartments, and a better understanding of geochemical tracer transport mechanism is essential for conservation and resource management. In this thesis, systematic data sets were collected from many typical environmental compartments both in China and Australia, including the catchment, desert, and typical mining sites at an alpine stream etc. Various geochemical tracers and methodologies, such as heavy metals and stable isotopes were applied to make a comprehensive exploration of the interactive impacts of human activity and natural processes on the transport and accumulation of geochemical tracers. The main findings of this thesis are:
(1) The species distribution model (SDM) can help improve the prediction accuracy of mapping geochemical tracers by considering the important explanatory variables. The prediction results of Chapter 2 and Chapter 3 confirmed the effectiveness and potential of leveraging SDMs from ecology to study heavy metal contamination in the field of hydrology, which offered new insights to understand the relationships between HMs and the human and physical environment.
(2) The combinations of interdisciplinary, multi-methods, various geochemical tracers, and indicators, facilitate the improvement of discovering the transport processes of tracers. In Chapter 3, the end member mixing analysis (EMMA) and SDM were combined to study the vertical hydraulic connections between surface water and groundwater. The water chemical tracers in river water were found to be able to serve as good explanatory variables to predict the HMs in soil in Chapter 4. And both elemental concentration and bioaccumulation ratio were used as the indicators to study the bioaccumulation processes in Chapter 6, which can provide more detailed information, otherwise the spatial attributes of the geochemical background information will be ignored. All these results supported this perspective.
(3) The model selection and model averaging methods constitute an advancement in quantitatively interpreting the relationships between isotopic signatures of precipitation and their local climatic variables. This method can supplement or precede more complex studies of hydrological cycles utilizing isotope tools.
Overall, the combination of various chemical tracers, as well as the introduction of powerful methodologies from related research fields, can effectively help improve the analysis accuracy. This thesis offers an improved understanding of the transport and accumulation of chemical tracers between different environmental compartments, and can provide useful database at the data scarce areas. The results of this thesis can also provide scientific strategies for the regional development and management.
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