scholarly journals Temporal and Spatial Distribution and Fluorescence Spectra of Dissolved Organic Matter in Plateau Lakes: A Case Study of Qinghai Lake

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3481
Author(s):  
Zheng Li ◽  
Zhenghui Fu ◽  
Yang Zhang ◽  
Yunyan Guo ◽  
Feifei Che ◽  
...  
Keyword(s):  
Organic Matter ◽  
Spatial Distribution ◽  
Dissolved Organic Matter ◽  
Fluorescence Intensity ◽  
Rapid Development ◽  
Water Environment ◽  
Anthropogenic Sources ◽  
Qinghai Lake ◽  
Total Fluorescence ◽  
Temporal And Spatial

Dissolved organic matter (DOM) has a great impact on the main pollution indicators of lakes (such as chemical oxygen demand, COD). Therefore, DOM is the research basis for understanding the meaning of the water environment and the laws of the migration and transformation of pollutants. Qinghai Lake is one of the world’s typical inland plateau lake wetlands. It plays important roles in improving and regulating the climate and in promoting a virtuous regional ecological cycle. In recent years, with the acceleration of urbanization and the rapid development of tourism, under the background of climate change, and with grassland degradation and precipitation change, the whole basin of Qinghai Lake has been facing great ecological pressure. In order to comprehensively explore the water environment of Qinghai Lake and to protect the sustainable development of the basin, a systematic study was carried out on the whole basin of Qinghai Lake. The results show the following: (1) from 2010 to 2020, the annual average value of CODCr in Qinghai Lake fluctuated in the range from class III to class V according to the surface water environmental quality standard, showing first a downward trend and then an upward trend. (2) The concentration of CDOM in Qinghai Lake had obvious temporal and spatial changes. (3) The spatial distribution of the total fluorescence intensity of FDOM in water was also different in different seasons. However, in the three surveys, the area with the highest total fluorescence intensity of FDOM in the water body appeared near Erlangjian in the south of Qinghai Province, indicating that anthropogenic sources are the main controlling factors of dissolved organic matter in the lake.

scholarly journals Temporal and Spatial Distribution and Fluorescence Spectra of Dissolved Organic Matter in Plateau Lakes -- A Case Study of Qinghai Lake

2021 ◽  
Author(s):  
Zheng Li ◽  
Zhenghui Fu ◽  
Yang Zhang ◽  
Yunyan Guo ◽  
Feifei Che ◽  
...  
Keyword(s):  
Organic Matter ◽  
Spatial Distribution ◽  
Dissolved Organic Matter ◽  
Lake Water ◽  
Water Body ◽  
Mean Value ◽  
Qinghai Lake ◽  
Temporal And Spatial Distribution ◽  
The Mean ◽  
Temporal And Spatial

Abstract Dissolved organic matter (DOM) has a great influence on the main pollution indexes of lakes (such as COD). Therefore, DOM research is the basis for understanding the water environmental quality and the law of pollutant migration and transformation in the basin. In this study, the water quality monitoring data of Qinghai Lake water body and 8 rivers around the lake from 2010 to 2020 were collected, and the dissolved organic matter (DOM) was synchronously sampled in May, September and October 2020. The optical characteristics of DOM, the temporal and spatial distribution of CDOM and the fluorescence spectrum and fluorescence component characteristics of FDOM were analyzed and studied. The results show that: (1) From 2010 to 2020, the annual mean value of CODCr of Qinghai Lake water body fluctuates in the range of Class III to Class V according to the environmental quality standard of the surface water, and shows a downward trend first and then an upward one. In general, the mean value of CODCr concentration in Qinghai Lake water body is at a high level and varies slightly among different months. (2) The mean value of CODCr concentration of the eight main rivers entering Qinghai Lake from 2010 to 2020 can be sorted from lowest to highest as follows: Ganzi River, Buha River, Jilmeng River, Hargai River, Shaliu River, Quanji River, HeMa River, and DaoTang River. (3) The concentration of CDOM in Qinghai Lake shows not only obvious seasonal variation (October, September and May, in the descending order) but also spatial variation. (4) The three-dimensional fluorescence spectrum matrix data of DOM in Qinghai Lake were analyzed by PARAFAC model, and four DOM fluorescence components with single maximum emission wavelength were analyzed.

Resolution of photo chemically induced changes of dissolved organic matter as function of cumulated radiation in a sample of a humic-rich and forested stream

2020 ◽  
Author(s):  
Peter Herzsprung ◽  
Christin Wilske ◽  
Wolf von Tümpling ◽  
Norbert Kamjunke ◽  
Oliver J. Lechtenfeld
Keyword(s):  
Drinking Water ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Fluorescence Intensity ◽  
Solar Irradiation ◽  
Large Reservoir ◽  
Photo Degradation ◽  
Peak Intensity ◽  
Ft Icr Ms ◽  
Ft Icr

<p>Photochemical processing is a major transformation pathway for allochthonous and autochthonous dissolved organic matter (DOM). DOM consists of thousands or even millions of different molecules and the isomer-resolved identification molecular structures is still far from any analytical realization. The highest analytical resolution of DOM can be achieved on a molecular mass basis via Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). With this technique, the molecular elemental compositions of thousands of DOM components can be assessed, given that they are extractable from water (via e.g. solid phase extraction, SPE-DOM) and ionizable (e.g. via electrospray ionization).</p><p>Increasing levels of DOC in drinking water reservoirs pose serious challenges for drinking water processing. Photochemical processes potentially influence the DOM quality in the reservoir water. The photo degradation and / or the photo production of DOM components in surface freshwater as function of cumulated radiation was rarely investigated. In order to fill this gap we performed an irradiation experiment with water from a shaded forest stream flowing into a large reservoir (Muldenberg, Germany). DOC concentration, UV absorption, excitation-emission-matrices (EEMs) including calculated PARAFAC components and fluorescence indices, and FT-ICR MS derived molecular formulas of SPE-DOM were recorded at 13 different time points. The cumulated radiation was recorded during six days of solar irradiation (sunny days in August at 50.401847 deg. latitude and 12.380528 deg. longitude). Changes in relative peak intensity of DOM components as function of cumulated radiation were evaluated both by Spearman`s rank correlation and linear regression.</p><p>We found components with different types of photo reaction behavior. Relative aliphatic components like C<sub>9</sub>H<sub>12</sub>O<sub>5</sub> were identified as photo products showing a monotonous mass peak intensity increase with irradiation time. Highly unsaturated and oxygen-rich components like C<sub>15</sub>H<sub>6</sub>O<sub>8</sub> showed a more or less monotonous intensity decrease indicating photo degradation. Many similar components were positively correlated to the humic-like fluorescence intensity and the humification index (HIX). The strong degradation of these components can explain the high loss of fluorescence intensity and the drop of the HIX in our experiment. As a result of the high temporal resolution in our experiment (i.e. intensity change as function of cumulated irradiation) we found another type of photo reaction. Components like C<sub>15</sub>H<sub>16</sub>O<sub>8</sub> showed first increasing and then decreasing intensity indicating the formation of intermediate products.</p><p>In general, the river DOM from the forested catchment area showed high potential for photochemical transformations which probably occur in the sunlight exposed predam of the drinking water reservoir.</p>

Factors Contributing to Haze and the Influence on External Insulation of Power Equipments

2014 ◽  
Vol 700 ◽  
pp. 631-636 ◽  
Author(s):  
Song Gao ◽  
Zhi Cheng Zhou ◽  
Lin Jun Yang ◽  
Yong Liu ◽  
Feng Bo Tao ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Power Transmission ◽  
Rapid Development ◽  
Temporal And Spatial Distribution ◽  
External Insulation ◽  
Weather Phenomenon ◽  
Haze Pollution ◽  
Power Load ◽  
Pollution Flashover ◽  
Temporal And Spatial

Haze-fog has been a severe pollution weather phenomenon in China due to a large number of emissions of pollutants with the rapid development of economy. The areas burst haze are usually coincidence with high density of electricity transmission line corridor or power load areas, and so the pollution flashover accidents happen frequently. In this paper the haze pollution situations and factors contributing to haze are introduced, and the mechanisms of haze inducing and aggravating the pollution flashover accidents are explained by analyzing the temporal and spatial distribution of PM2.5 and size characteristics of dust deposited transmission. Moreover, the influences of haze on power transmission and transformation equipment external insulation are discussed with combining the simulation pollution flashover experiments of high conductivity fog.

scholarly journals Flocculation of dissolved organic matter controls the distribution of iron in boreal estuarine sediments

2017 ◽  
Author(s):  
Tom Jilbert ◽  
Eero Asmala ◽  
Christian Schröder ◽  
Rosa Tiihonen ◽  
Jukka-Pekka Myllykangas ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Particulate Material ◽  
Estuarine Sediments ◽  
Anthropogenic Sources ◽  
Diagenetic Processes ◽  
Fe Content ◽  
Estuarine Zone ◽  
Organic Matter Pool ◽  
Boreal River

Abstract. Iron (Fe) plays a key role in sedimentary diagenetic processes in coastal systems, participating in various redox reactions and influencing the burial of organic carbon. Large amounts of Fe enter the marine environment from boreal river catchments associated with dissolved organic matter (DOM). However, the fate of this Fe pool in estuarine sediments has not been extensively studied. Here we show that flocculation of DOM along salinity gradients in an estuary of the northern Baltic Sea efficiently transfers Fe from the dissolved phase into particulate material that accumulates in the sediments. Consequently, we observe a decline with distance offshore in both the Fe content of the sediments and proportion of terrestrial material in the sedimentary organic matter pool. Mössbauer spectroscopy and sequential extractions suggest that large amounts of Fe in sediments of the upper estuarine zone are associated with organic matter as unsulfidized Fe (II) complexes, or present in the form of ferrihydrite, implying a direct transfer of flocculated material to the sediments. Accordingly, the contribution of these components to the total sedimentary Fe declines with distance offshore while other Fe phases become proportionally more important. Sediment core records show that the observed lateral distribution of Fe minerals has remained similar over recent decades, despite variable Fe inputs from anthropogenic sources and eutrophication of the coastal zone. Pore water data suggest that the vertical zonation of diagenetic processes in the sediments is influenced by both the availability of Fe and by bottom water salinity, which controls the availability of sulfate (SO42−).

scholarly journals Fast-freezing with liquid nitrogen preserves bulk dissolved organic matter concentrations, but not its composition

2016 ◽  
Author(s):  
Lisa Thieme ◽  
Daniel Graeber ◽  
Martin Kaupenjohann ◽  
Jan Siemens
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Liquid Nitrogen ◽  
Water Samples ◽  
Terrestrial Ecosystems ◽  
Spectroscopic Properties ◽  
Fluorescence Excitation ◽  
Total Fluorescence ◽  
Fluorescence Excitation Emission Matrices ◽  
Fast Freezing

Abstract. Freezing can affect concentrations and spectroscopic properties of dissolved organic matter (DOM) in water samples. Nevertheless, water samples are regularly frozen for sample preservation. In this study we tested the effect of different freezing methods (standard freezing at −18 °C and fast-freezing with liquid nitrogen) on DOM concentrations measured as organic carbon (DOC) concentrations and on spectroscopic properties of DOM from different terrestrial ecosystems (forest and grassland). Fresh and differently frozen throughfall, stemflow and soil solution samples were analyzed for DOC concentrations, UV-vis absorption and fluorescence excitation-emission matrices combined with parallel factor analysis (PARAFAC). Fast-freezing with liquid nitrogen prevented a significant decrease of DOC concentrations observed after freezing at −18 °C. Nonetheless, the share of PARAFAC components 1 (EXmax < 250 nm (340 nm), EMmax: 480 nm) and 2 (EXmax: 335 nm, EMmax: 408 nm) to total fluorescence and the humification index (HIX) decreased after both freezing treatments, while the shares of component 3 (EXmax: < 250 nm (305 nm), EMmax: 438 nm) as well as SUVA254 increased. The contribution of PARAFAC component 4 (EXmax: 280 nm, EMmax: 328 nm) to total fluorescence was not affected by freezing. We recommend fast-freezing with liquid nitrogen for preservation of bulk DOC concentrations of samples from terrestrial sources, whereas immediate measuring is preferable to preserve spectroscopic properties of DOM.

scholarly journals Discharge and Temperature Controls of Dissolved Organic Matter (DOM) in a Forested Coastal Plain Stream

Water ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 2919
Author(s):  
Yuehan Lu ◽  
Peng Shang ◽  
Shuo Chen ◽  
Yingxun Du ◽  
Marco Bonizzoni ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
High Temperatures ◽  
Coastal Plain ◽  
Stream Water ◽  
Water Discharge ◽  
Low Flow ◽  
Fluorescence Excitation ◽  
In Situ Modification ◽  
Total Fluorescence

Streams in the southeastern United States Coastal Plains serve as an essential source of energy and nutrients for important estuarine ecosystems, and dissolved organic matter (DOM) exported from these streams can have profound impacts on the biogeochemical and ecological functions of fluvial networks. Here, we examined hydrological and temperature controls of DOM during low-flow periods from a forested stream located within the Coastal Plain physiographic region of Alabama, USA. We analyzed DOM via combining dissolved organic carbon (DOC) analysis, fluorescence excitation–emission matrix combined with parallel factor analysis (EEM-PARAFAC), and microbial degradation experiments. Four fluorescence components were identified: terrestrial humic-like DOM, microbial humic-like DOM, tyrosine-like DOM, and tryptophan-like DOM. Humic-like DOM accounted for ~70% of total fluorescence, and biodegradation experiments showed that it was less bioreactive than protein-like DOM that accounted for ~30% of total fluorescence. This observation indicates fluorescent DOM (FDOM) was controlled primarily by soil inputs and not substantially influenced by instream production and processing, suggesting that the bulk of FDOM in these streams is transported to downstream environments with limited in situ modification. Linear regression and redundancy analysis models identified that the seasonal variations in DOM were dictated primarily by hydrology and temperature. Overall, high discharge and shallow flow paths led to the enrichment of less-degraded DOM with higher percentages of microbial humic-like and tyrosine-like compounds, whereas high temperatures favored the accumulation of high-aromaticity, high-molecular-weight, terrestrial, humic-like compounds in stream water. The flux of DOC and four fluorescence components was driven primarily by water discharge. Thus, the instantaneous exports of both refractory humic-like DOM and reactive protein-like DOM were higher in wetter seasons (winter and spring). As high temperatures and severe precipitation are projected to become more prominent in the southeastern U.S. due to climate change, our findings have important implications for future changes in the amount, source, and composition of DOM in Coastal Plain streams and the associated impacts on downstream carbon and nutrient supplies and water quality.

scholarly journals Characterizing variations of dissolved organic matter (DOM) properties in Nansi Lake: an important reservoir along the eastern route of China’s South-to-North Water Diversion Project

2021 ◽  
Author(s):  
Haoyu Ren ◽  
Xin Yao ◽  
Feiyang Ma ◽  
Tuantuan Fan ◽  
Huanguang Deng ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Fluorescence Intensity ◽  
Great Influence ◽  
Principal Component ◽  
Water Diversion ◽  
Nansi Lake ◽  
Water Diversion Project ◽  
North Water ◽  
Aquatic Productivity

Abstract Variations in dissolved organic matter (DOM) quality has far-reaching implications that affect, e.g., aquatic productivity, food web structures, trace element and pollutant transport. In this study, a total of 186 water samples were collected at 62 sites (three points in time within one year) in Nansi Lake. UV-Vis spectra, Synchronous fluorescence (SF) spectra, the excitation-emission matrix and parallel factor analysis (EEM-PARAFAC) were applied to indicate the source and quality of DOM. Water transferring of the eastern route of China’s South-to-North Water Diversion Project had a great influence on the water level of Nansi Lake. Results of SF spectra, EEM-PARAFAC and principal component analysis (PCA) suggested that protein-like substances played a more important role in DOM properties in April and July than October. This result is related to a high fluorescence intensity occurred in April (Fmax=0.72±0.03 in the upper lake and 1.84±0.13 in the lower lake) and July (Fmax=1.10±0.05 in the upper lake and 1.49±0.04 in the lower lake), which might be caused by water transferring from other lakes to Nansi Lake, death and decomposition of submerged plants. At the same time, relatively good correlations were found between humic-like substances, DOC and a254 in April, July and October, which indicated the important contribution of humic-like substances to Nansi Lake. With the completion of the water diversion, the ratio of the fluorescence intensity of component to the total fluorescence intensity (%Fmax) suggested that the proportion of humic-like substances started to increase. And when it came to October, humic-like substances become the main substance in DOM collected from Nansi Lake (%Fmax=66.56%±0.58% in the upper lake and 61.98%±0.99% in the lower lake). Moreover, among the two areas in Nansi Lake, the upper lake always had a higher degree of humification (HIX=2.23±0.06, 2.38±0.11 and 3.10±0.05 in April, July and October, respectively) than the lower lake (HIX=1.06±0.05, 1.68±0.05 and 2.62±0.08 in April, July and October, respectively), which implied extraneous contaminants might have a more important impact on DOM properties in the upper lake.

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