Linking biological toxicity and the spectral characteristics of contamination in seriously polluted urban rivers

Abstract

Background: Urban river pollution risks to environments and human health are emerging as a serious concern worldwide. With the aim to achieve the health of urban river ecosystem, numerous monitoring programs have been implemented to investigate the spectral characteristics of contamination. While due to the complexity of aquatic pollutants, the linkages between harmful effects and the spectral characteristics of contamination are still a major challenge for capturing main threats to urban aquatic environments. To establish these linkages, surface water (SW), sediment pore water (SDPW), and riparian soil pore water (SPW) were collected from five sites of the seriously polluted Qingshui Stream, China. The water-dissolved organic carbon (DOC), total nitrogen (TN), total phosphate (TP), fluorescence excitation-emission matrix, and specific ultraviolet absorbance were applied to analyze the spectral characteristics of urban river contamination. The Photobacterium phosphorem 502 was used to test the acute toxicity of the samples. Finally, the correlations between acute toxicity and concentrations of DOC, TN, TP, and the spectral characteristics were explored. Results: The concentrations of DOC, TN, and TP in various samples amounted from 11.41 ± 2.31 to 3844.67 ± 87.80 mg/L, from 1.96 ± 0.06 to 906.23 ± 26.01 mg/L and from 0.06 ± 0.01 to 101.00 ± 8.29 mg/L, respectively. The florescence index (FI) amounted from 1.54 to 3.14, the biological index (BIX) were between 0.94 and 1.57. The distribution patterns of specific ultraviolet absorbance at 254 nm (SUVA 254) showed that the highest aromaticity and hydrophobicity were found in SDPW and the lowest ones were in SW. All samples showed significantly inhibition on luminescent bacteria. Particularly, the highest acute toxicity was found in site 1 with an EC 50 value of 6.023-fold dilution for the raw SDPW sample. In addition, the highest fluorescence intensity was also observed from SDPW of site 1. Conclusions: Tryptophan-like and protein-like substances could be important DOC fractions contributing remarkably to the acute toxicity in the seriously polluted river. In addition, the significant reduction on acute toxicity was found with the treatment of surface water flow constructed wetland, revealing that constructed wetland could be an effective approach for toxicant degradation. These observations are useful for water treatments, and meaningful for urban sustainable development.

Assessing extracted organic matter quality from river sediments by elemental and molecular characterization: Application to the Tietê and Piracicaba Rivers (São Paulo, Brazil)

“…The optical properties of EOMSed proved to be more efficient for assessing the quality and composition of sediments than those of WEOMSed due to the better discrimination between the fluorescence components in the alkaline extracts. Although water extraction has been used to assess OM sources and link contamination in polluted urban rivers (Chen et al, 2019;Zhang et al, 2020), in our study, alkaline extracts were better at describing the properties of OM.…”

Pollinators and urban riparian vegetation: important contributors to urban diversity conservation

“…The high quality of corridors is benefit for moderating some of the adverse ecological effects of habitat fragmentation induced by urbanization process. However, urban rivers are susceptible to severe habitat degradation and pollution in the past decade [19], and their ecological function on linking the fragmented habitats is neglected. Conservation, restoration and rehabilitation of the urban river can not only benefit to the river ecosystem itself, but also establish the network for biodiversity connections [20].…”

“…1) were selected, according to the study by Rollin in other areas [22]. The Qingshui stream (QS) and Phoenix stream (PS) both originate from the Gele mountain with lengths of 15.9 km and 7.1 km, respectively [19]. Along the stream longitudinal, 5 sampling sites at the riparian zone of the QS and 4 sampling sites for PS were set up, of which 3 transects with length of 50 m along the stream were involved within each site [23].…”