Dissolved Metal(loid) Concentrations and Their Relations with Chromophoric and Fluorescent Dissolved Organic Matter in an Urban River in Shenzhen, South China

Abstract

Urbanization is often accompanied by aquatic metal(loid) pollution, which is regulated by dissolved organic matter (DOM). However, the relationships between dissolved metal(loid) concentration and the bulk, chromophoric, and fluorescent DOM in black and odorous urban rivers are still poorly understood. Here, we investigated the dissolved metal(loid) concentrations of Zn, Cu, Cr, As, Pb, and Cd and their correlations with DOM-related parameters in water samples from a polluted urbanized watershed in Shenzhen, China. The results showed that the Zn and Cu concentrations in the mainstream and tributary exceeded the national standards, and the wastewater treatment plant (WWTP) was an important source, as indicated by the abrupt concentration increases downstream of the WWTP. The dissolved metal(loid) concentrations were not always significantly correlated with the dissolved organic carbon (DOC) concentration or the ultraviolet absorbance at 254 nm (UV254); however, they were more likely to be correlated with the maximum fluorescence intensity (Fmax) of protein-like fluorescent DOM components. A strong correlation between the Cu/DOC ratio and specific UV254 (SUVA254) previously reported did not exist in the present study. Instead, the Cu/DOC ratio was positively correlated with the Fmax/DOC ratios for protein-like fluorescent DOM components. Our study highlights that protein-like fluorescent DOM may be more important than humic-like fluorescence DOM and chromophoric DOM in terms of interacting with dissolved metal(loid)s in black and odorous urban rivers.

Copper Distribution and Binding Affinity to Size-Fractioned Dissolved and Particulate Organic Matter in River Sediment

“…The bulk DOC concentration in the DOM solutions was slightly higher than the DOC concentrations found in general river water [23,25,46,47], and similar to river water that received municipal and industrial wastewater [40,48,49]. The bulk DOM Cu concentrations were 51.2 ± 6.8 and 21.0 ± 6.1 µg L −1 , which were higher than the unpolluted river water [23,25,46,[48][49][50].…”

Sequential UV and chlorine disinfection induced change of biofilm-originated disinfection byproducts formation potential in drinking water distribution system: Effect of UV dose and influencing mechanism

“…Obviously, protein-like (represented by C1 or PN) and SMP-like components in bio lm EPS were main contributors to bio-ori-DBPFP. Considering the fact that most of DOM in nished water of waterworks was medium-size molecular weight and dominated by negative-charge natural organic matters (Deng et al 2019;Zhang et al 2020), neutral and hydrophobic fractions of DOM were supposed to be the main force attaching to bio lm EPS based on the physicochemical characteristics of EPS (Z. Wang et al 2012).…”

A Simple Method to Identify the Dominant Fouling Mechanisms during Membrane Filtration Based on Piecewise Multiple Linear Regression

“…The modeling results were further evidenced by the consecutive measurements of the permeate properties during the filtration process. The TOC measured the total dissolved organic matter (DOM), UV absorbance at 254 nm (UV 254 ) indicated the chromophoric portion of the DOM such as proteins and other unsaturated components [34,35], and the averaged fluorescence intensity at the emission wavelength range of 380-500 nm (FI 380-500 ) mainly reflected the humic components of the DOM [33,36]. In Figure 6, the permeate TOC and UV 254 both show a "Z"-shaped decreasing trend with the increase of V. At stages 5-6, the TOC dropped sharply, indicating that the overall rejection rate of organic foulants rose sharply due to the formation of a cake/gel layer on the membrane surface.…”