Abstract
BackgroundUrban 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.ResultsThe 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 (SUVA254) 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 EC50 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.ConclusionsTryptophan-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.
Highlights
Urban river pollution risks to environments and human health are emerging as a serious concern worldwide
We found that dissolved organic carbon (DOC) concentrations in surface water (SW) amounting from 51.15 ± 0.38 to 55.54 ± 5.77 mg/L, which were higher than that in sediment pore water (SDPW) ranging from 25.82 ± 0.97 to 42.54 ± 1.06 mg/L) along the stream longitudinal gradients with an exception in site 1 (3844.67 ± 87.80 mg/L)
We found that the biological index (BIX) fluctuated slightly along with the stream longitudinal gradients, amounting from 0.94 to 1.46 for soil pore water (SPW), from 1.08 to 1.13 for SW, and from 0.97 to 1.57 for SDPW, respectively
Summary
Urban river pollution risks to environments and human health are emerging as a serious concern worldwide. 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. While as required by the “Sustainable cities and communities”, two-thirds of global population (6.5 billion people) will live in cities by 2050, which will induce extensive widespread anthropogenic activities [3] With these enormous increases of anthropogenic activities, overload pollutants deriving from industrial, agricultural, and household sewage will continuously emit into urban rivers, resulting in serious pollution for urbanized watersheds [4, 5]. The black-odor water has been recognized as one of the most challenge for publics, government as well as academics [7]
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