Spatial Variations of Trace Metals and Their Complexation Behavior with DOM in the Water of Dianchi Lake, China

Abstract

The dynamics of trace metals and the complexation behavior related to organic matter in the interface between water and sediment would influence water quality and evolution in the lake system. This study characterized the distribution of trace metals and the optical properties of dissolved organic matter (DOM) on the surface, and the underlying and pore water of Dianchi Lake (DC) to understand the origin of metals and complexation mechanisms to DOM. Some species of trace metals were detected and Al, Ti, Fe, Zn, Sr and Ba were found to be the main types of metals in the aquatic environment of DC. Ti, Fe, Sr and Ba predominated in water above the depositional layer. Al, Ti, Fe and Sr were the most abundant metallic types in pore water. Mn and Zn were the main type found at the southern lake site, reflecting the contribution of pollution from an inflowing river. The correlations between DOM and metals suggested that both originated from the major source as particulate organic matter (POM), associated with weathering of Ca-, Mg-carbonate detritus and Fe- or Mn-bearing minerals. High dynamics of DOM and hydrochemical conditions would change most metal contents and speciation in different water compartments. Proportions of trace metals in dissolved organic carbon (DOC) in natural waters were correlated with both DOM molecular weight and structure, different metals were regulated by different organic properties, and the same metal also had specific binding characteristic with DOM in various water compartments. This study highlighted the interrelation of DOM and metals, as well as the pivotal role that organic matter and nutrients played during input, migrations and transformations of metals, thereby reflecting water quality evolution in the lake systems.

Copper Distribution and Binding Affinity of Size-Fractioned Humic Substances Taken from Paddy Soil and Correlation with Optical Characteristics

“…However, the studies were lacking the molecular weight effect on the ratio difference in the soil solutions. In an aquatic environment, the [Cu]/[DOC] ratios of bulk DOM had been reported by some researchers [16,29,30,32,33]. The ratios were positively correlated with aromaticity for natural water DOM [29,32].…”

“…The copper and organic matter binding affinity, [Cu]/[DOC] ratio, was used to understand the variation in the binding ability of copper to DOM/WEOM [10,11,16,[29][30][31][32][33]. Table 4 lists the [Cu]/[DOC] ratios of bulk and size-fractioned AEOM solutions for each site.…”

“…To understand the HM-AEOM binding behavior, the AEOM chemical composition and structure needs to be included [6,8,11]. The HM and DOM binding affinity, [Me]/[DOC] ratio, is a useful parameter and has been used to investigate the preferences, distribution, bioavailability, and mobility potential of HMs binding with DOM/AEOM [9][10][11]16,[29][30][31][32][33]. Moreover, the HM-AEOM binding affinity in various molecular weight AEOMs is an important factor in understanding the HM binding behavior.…”

“…Therefore, extracted soil organic matter was separated into size fractions to investigate sizefractioned [HM]/[DOC] ratios. This is an excellent surrogate indicator for understanding heavy metals' binding strength and preference, distribution, bioavailability, and mobility potential in soil environments [9][10][11]16,[29][30][31][32][33]. At the same time, using sensitive and rapid optical indicators to understand the chemical composition and structure of the extracted organic matter can simplify the analysis of the dominant factors that influence HMs-OM binding affinity.…”

Optical property of dissolved organic matter and its correlation with heavy metals in surface water around metal mines to be exploited in southern Anhui Province, China

“…DOM has a significant impact on the migration and transformation of Mn in groundwater. Yi et al (2019) analyzed the relationship between DOM and heavy metals in the water of Dianchi Lake and found that DOM and heavy metals have complex effects. Hongxia et al (2014) using excitationemission matrix fluorescence spectroscopy (EEM) was combined with parallel factor analysis to analyze the fluorescence components of DOM in surface water of rare earth mining areas, finding there was a significant positive correlation between protein-like components and rare earth metals.…”