| 1. |
- Zhou, Yongqiang, et al.
(författare)
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Rainstorms drive export of aromatic and concurrent bio-labile organic matter to a large eutrophic lake and its major tributaries
- 2023
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 229
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Tidskriftsartikel (refereegranskat)abstract
- Lakes are hotspots for global carbon cycling, yet few studies have explored how rainstorms alter the flux, composition, and bio-lability of dissolved organic matter (DOM) in inflowing rivers using high-frequency monitoring. We conducted extensive campaigns in the watershed of Lake Taihu and made daily observations for three years in its two largest inflowing tributaries, River Dapu and River Yincun. We found higher DOC, bio-labile DOC (BDOC), and specific UV absorbance (SUVA(254)) levels in the northwestern inflowing regions compared with the remaining lake regions. DOC and BDOC increased during rainstorms in River Dapu, and DOC declined due to local dilution and BDOC increased during rainstorms in River Yincun. We found that rainstorms resulted in increased DOM absorbance a(350), SUVA(254), and humification index (HIX) and enhanced percentages of humic-like fluorescent components, %polycyclic condensed aromatic and %polyphenolic compounds as revealed from ultrahigh-resolution mass spectrometry (FT-ICR MS), while spectral slope (S275-295) and the percentages of protein-like C1 and C3 declined during rainstorms compared with other seasons. This can be explained by a combined flushing of catchment soil organic matter and household effluents. The annual inflows of DOC and BDOC to Lake Taihu were 1.15 +/- 0.18 x 10(4) t C yr(-1) and 0.23 +/- 0.06 x 104 t C yr(-1) from River Dapu and 2.92 +/- 0.42 x 103 t C yr(-1) and 0.53 +/- 0.07 x 10(3) t C yr(-1) from River Yincun, respectively, and the fluxes of DOC and BDOC from both rivers increased during rainstorms. We found an elevated frequency of heavy rainfall and rainstorms in the lake watershed during the past six decades. We conclude that an elevated input of terrestrial organic-rich DOM with concurrent high aromaticity and high bio-lability from inflowing rivers is likely to occur in a future wetter climate.
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| 2. |
- Zhou, Lei, et al.
(författare)
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Eutrophication alters bacterial co-occurrence networks and increases the importance of chromophoric dissolved organic matter composition
- 2021
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Ingår i: Limnology and Oceanography. - : John Wiley & Sons. - 0024-3590 .- 1939-5590. ; 66:6, s. 2319-2332
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Tidskriftsartikel (refereegranskat)abstract
- Eutrophication affects bacterial communities by fueling them with nutrients and carbon sources. While the influence of physicochemical conditions on bacterial communities is well studied, little is known about how dissolved organic matter (DOM) quality affects bacterial interspecific interactions and community composition with increasing eutrophication. Here, we examined the relative importance of physicochemical conditions and chromophoric DOM (CDOM) composition for bacterial community variation across trophic gradients using 109 samples data collected in 33 lakes of the Yangtze-Huaihe River basin. We found a notable increase of bacterial abundance, elevated modularity of co-occurrence networks, and decreased habitat niche breadths from mesotrophic sites to hyper-eutrophic sites, suggesting changes in co-occurrence patterns with eutrophication. Variation partitioning revealed that the proportion purely explained by CDOM composition was higher at the moderate- and hyper-eutrophic sites than at the mesotrophic sites. Moreover, the module structures of the networks correlated significantly with CDOM composition at the eutrophic sites but not at the mesotrophic sites. The significant negative correlation between community-level habitat niche breadths and the intensities of the protein-like components at the moderate- and hyper-eutrophic sites indicates a strong association between biolabile protein-like compounds and habitat specialists in nutrient and substrate enriched lake systems. Our results suggest that consideration of DOM composition can strengthen the identification of links between environmental factors and bacterial community composition and interspecific interactions, especially under resource-rich conditions.
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| 3. |
- Zhou, Yongqiang, et al.
(författare)
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Inflow rate-driven changes in the composition and dynamics of chromophoric dissolved organic matter in a large drinking water lake
- 2016
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 100, s. 211-221
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Tidskriftsartikel (refereegranskat)abstract
- Drinking water lakes are threatened globally and therefore in need of protection. To date, few studies have been carried out to investigate how the composition and dynamics of chromophoric dissolved organic matter (CDOM) in drinking water lakes are influenced by inflow rate. Such CDOM can lead to unpleasant taste and odor of the water and produce undesirable disinfection byproducts during drinking water treatment. We studied the drinking water Lake Qiandao, China, and found that the concentrations of suspended particulate matter (SPM) in the lake increased significantly with inflow rate (p
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| 4. |
- Zhou, Yongqiang, et al.
(författare)
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Rainstorm events shift the molecular composition and export of dissolved organic matter in a large drinking water reservoir in China : High frequency buoys and field observations
- 2020
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 187
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Tidskriftsartikel (refereegranskat)abstract
- Rainstorm events can flush large amounts of terrestrial organic-rich material into lakes that are used for drinking water. To date, few studies have been carried out to investigate how rainstorm events change the molecular composition, bio-lability, and flux of upstream-imported dissolved organic matter (DOM), which can impact the odor and taste of drinking water as well as the efficiency of wastewater treatment. We undertook high-frequency buoy monitoring and point sample collection (n = 495), during high, moderate, and low inflow discharge, in Lake Qiandao, a key drinking water source for about 10 million people. Data from two online fluorescent DOM sensors deployed and field samples collected at the river site, Jiekou, and the lake site, Xiaojinshan, showed that rainstorm events increased the specific UV absorbance (SUVA254), humification index (HIX), humic-like components (C1-C2), and FT-ICR MS derived condensed aromatic and polyphenolic compounds (p < 0.001) and decreased the spectral slope of DOM (S275–295), spectral slope ratio (SR), biological index (BIX), and highly bio-degradable peptide-like and aliphatic substances (p < 0.001). Our results suggest that rainstorm events enhanced the export to the lake of colored, hydrophobic, and aromatic DOM. Upstream-derived dissolved organic carbon (DOC) concentrations decreased (p < 0.001), while DOC bio-availability (BDOC) increased only slightly (p < 0.05) during rainstorm events. The loss rate of DOC in Lake Qiandao is 0.82 × 104 t C yr−1, of which 0.30 × 104 t C yr−1 is highly bio-labile, and higher occurrences of both ≥ 25 mm d − 1 and ≥ 50 mm d − 1 rainfall events are anticipated by linear fittings for this region in the future. The application of in situ fluorescence sensors provides an early warning of DOC surge incidents caused by rainstorm events and may be useful in advising drinking water treatment plant managers of changes in raw water DOM quality and treatability.
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| 5. |
- Zhou, Yongqiang, et al.
(författare)
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Unraveling the Role of Anthropogenic and Natural Drivers in Shaping the Molecular Composition and Biolability of Dissolved Organic Matter in Non-pristine Lakes
- 2022
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 56:7, s. 4655-4664
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Tidskriftsartikel (refereegranskat)abstract
- Lakes receive and actively process terrestrial dissolved organic matter (DOM) and play an important role in the global carbon cycle. Urbanization results in elevated inputs of nonpoint-source DOM to headwater streams. Retention of water in lakes allows time for alteration and transformation of the chemical composition of DOM by microbes and UV radiation. Yet, it remains unclear how anthropogenic and natural drivers impact the composition and biolability of DOM in non-pristine lakes. We used optical spectroscopy, Fourier transform ion cyclotron mass spectrometry, stable isotopic measurements, and laboratory bioincubations to investigate the chemical composition and biolability of DOM across two large data sets of lakes associated with a large gradient of urbanization in lowland Eastern China, encompassing a total of 99 lakes. We found that increased urban land use, gross domestic products, and population density in the catchment were associated with an elevated trophic level index, higher chlorophyll-a, higher bacterial abundance, and a higher amount of organic carbon with proportionally higher contribution of aliphatic and peptide-like DOM fractions, which can be highly biolabile. Catchment areas, water depth, lake area: catchment area, gross primary productivity, delta O-18-H2O, and bacterial abundance, however, had comparatively little linkage with DOM composition and biolability. Urban land use is currently intensifying in many developing countries, and our results anticipate an increase in the level of biolabile aliphatic DOM from nonpoint sources and accelerated carbon cycling in lake ecosystems in such regions.
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