THESIS
2016
xii, 126 pages : illustrations (some color) ; 30 cm
Abstract
Severe metal pollution due to industrial effluent releases has been documented in Jiulong
River estuary which locates in Fujian Province, southern China. In the present study, time-series
based water samplings were conducted during effluent discharge events to reveal the metal
partitioning in the dissolved, particulate and colloidal phases. Different behaviors of metals in the
dissolved fraction against salinity indicated different sources. Enhanced adsorption as well as
formation of particulates resulted in elevated partitioning for Cu and Zn during the mixing
process. Colloidal metals displayed positive correlations with dissolved or colloidal organic
carbon, while constant colloidal partitioning suggested the excess binding capacity. Diffusive
gradient in thin films (DGT) tec...[
Read more ]
Severe metal pollution due to industrial effluent releases has been documented in Jiulong
River estuary which locates in Fujian Province, southern China. In the present study, time-series
based water samplings were conducted during effluent discharge events to reveal the metal
partitioning in the dissolved, particulate and colloidal phases. Different behaviors of metals in the
dissolved fraction against salinity indicated different sources. Enhanced adsorption as well as
formation of particulates resulted in elevated partitioning for Cu and Zn during the mixing
process. Colloidal metals displayed positive correlations with dissolved or colloidal organic
carbon, while constant colloidal partitioning suggested the excess binding capacity. Diffusive
gradient in thin films (DGT) technique was then employed together with sediment cores to study
the porewater dynamics of trace metals as well as benthic exchange fluxes. With the redox
condition showing spatial and temporal variations, precipitation as sulfides and adsorption onto
Mn/Fe (hydr)oxides were important in scavenging metals from porewaters in this estuarine area.
Estimated fluxes at sediment-water interface indicated the overlying water as a major source for
trace metals, whereas sediment could also be the source if surface remobilization dominated. In
addition, taking advantage of flow field-flow fractionation (FlFFF) technique, colloidal size
distribution of organic matter and metals was quantified. A dominance of dissolved metals in the
1-10 kDa fraction was demonstrated, which was regulated by terrestrial fulvic acid input. The
small sized colloidal organic complexes were responsible for stabilizing trace metals. And
variations in particle size fractions indicated different sources, fates and geochemical controls of the metals. Our results highlighted the impacts of both natural and anthropogenic processes on
trace metal behaviors in the dynamic system. Results from these studies will further provide
information on metal toxicity prediction, environmental impact assessment and pollution
mitigation.
Post a Comment