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

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 281 ◽  
Author(s):  
Song Zhang ◽  
Xun-Wen Chen ◽  
Quanhui Ye ◽  
Zi-Ting Zhang ◽  
Si-Fang Kong ◽  
...  
Keyword(s):  
Organic Matter ◽  
Wastewater Treatment ◽  
Organic Carbon ◽  
Dissolved Organic Matter ◽  
Treatment Plant ◽  
National Standards ◽  
Urban Rivers ◽  
Ultraviolet Absorbance ◽  
Fluorescent Dissolved Organic Matter ◽  
Doc Concentration

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.

scholarly journals Seasonal Changes in Dissolved Organic Matter Composition in a Patagonian Fjord Affected by Glacier Melt Inputs

2021 ◽  
Vol 8 ◽  
Author(s):  
Matthew G. Marshall ◽  
Anne M. Kellerman ◽  
Jemma L. Wadham ◽  
Jon R. Hawkings ◽  
Giovanni Daneri ◽  
...  
Keyword(s):  
Organic Matter ◽  
Surface Layer ◽  
Organic Carbon ◽  
Dissolved Organic Matter ◽  
Relative Contribution ◽  
Glacier Melt ◽  
Level Data ◽  
Chilean Patagonia ◽  
Doc Concentration ◽  
Dom Composition

Biogeochemical processes in fjords are likely affected by changes in surrounding glacier cover but very little is known about how meltwater directly influences dissolved organic matter (DOM) in fjords. Moreover, the data available are restricted to a handful of northern hemisphere sites. Here we analyze seasonal and spatial variation in dissolved organic carbon (DOC) concentration and DOM composition (spectrofluorescence, ultrahigh resolution mass spectrometry) in Baker-Martinez Fjord, Chilean Patagonia (48°S), to infer the impacts of rapid regional deglaciation on fjord DOM. We show that surface layer DOC concentrations do not vary significantly between seasons, but DOM composition is sensitive to differences in riverine inputs. In summer, higher protein-like fluorescence reflects increased glacial meltwater inputs, whilst molecular level data show weaker influence from marine DOM due to more intense stratification. We postulate that the shifting seasonal balance of riverine and marine waters affects the supply of biolabile peptides and organic nitrogen cycling in the surface layer. Trends in DOM composition with increasing salinity are consistent with patterns in estuaries (i.e. preferential removal of aromatic compounds and increasing relative contribution of unsaturated and heteroatom-rich DOM from marine sources). Preliminary estimates also suggest that at least 10% of the annual organic carbon stock in this fjord is supplied by the four largest, glacially fed rivers and that these inputs are dominated by dissolved (84%) over particulate organic carbon. Riverine DOC may therefore be an important carbon subsidy to bacterial communities in the inner fjord. The overall findings highlight the biogeochemical sensitivity of a Patagonian fjord to changes in glacier melt input, which likely has relevance for other glaciated fjords in a warming climate.

scholarly journals The non-conservative distribution pattern of organic matter in Rajang, a tropical river with peatland in its estuary

2019 ◽  
Author(s):  
Zhuoyi Zhu ◽  
Joanne Oakes ◽  
Bradley Eyre ◽  
Youyou Hao ◽  
Edwin Sien Aun Sia ◽  
...  
Keyword(s):  
Amino Acids ◽  
Organic Matter ◽  
Organic Carbon ◽  
Dissolved Organic Matter ◽  
Anthropogenic Activities ◽  
Field Investigation ◽  
Organic Matter Composition ◽  
Doc Concentration ◽  
Nitrogen Ratio ◽  
Export Pattern

Abstract. South-east Asian peatland-draining rivers have attracted much attention due to their high dissolved organic carbon (DOC) yield and high CO2 emissions under anthropogenic activities. In August 2016, we carried out a field investigation of the Rajang river and estuary, a tropical system located in Sarawak, Malaysia. The Rajang has peatland in its estuary while the river basin is covered by tropical rainforest. DOC δ13C in the Rajang ranged from −28.7 ‰ to −20.1 ‰ and a U-shaped trend from river to estuary was identified. For particulate organic carbon (POC), the δ13C ranged between −29.4 ‰ to −31.1 ‰ in the river and a clear increasing trend towards more δ13C -enriched with higher salinity existed in the estuary. In the estuary, there was a linear conservative dilution pattern for dissolved organic matter composition (as quantified by D/L amino acids enantiomers) plotted against DOC δ13C, whereas when plotted against salinity dissolved D/L amino acids enantiomers values were higher than the theoretical dilution value. Together, these data indicate that the addition of DOC in estuary (by peatland) not only increased the DOC concentration, but also altered its composition, by adding more bio-degraded, 13C-depleted organic matter into the bulk dissolved organic matter. Alteration of organic matter composition (adding of more degraded subpart) was also apparent for the particulate phase, but patterns were less clear. The Rajang was characterized by DOC / DON ratios of 50 in the river section, with loss of DON in the estuary increased the ratio to 140, suggesting the unbalanced export pattern for organic carbon and nitrogen, respectively. Under anthropogenic activities, further assessment of organic carbon to nitrogen ratio is needed.

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