The effects of climate warming on microbe-mediated mechanisms of sediment carbon emission.

Due to significant differences in biotic and abiotic properties of soils compared to those of sediments, the predicted underlying microbe-mediated mechanisms of soil carbon emissions in response to warming may not be applicable for estimating similar emissions from inland water sediments. We addressed this issue by incubating different types of sediments, (including lake, small river, and pond sediments) collected from 36 sites across the Yangtze River basin, under short-term experimental warming to explore the effects of climate warming on sediment carbon emission and the underlying microbe-mediated mechanisms. Our results indicated that under climate warming CO emissions were affected more than CH emissions, and that pond sediments may yield a greater relative contribution of CO to total carbon emissions than lake and river sediments.

Properties and metal binding behaviors of sediment dissolved organic matter (SDOM) in lakes with different trophic states along the Yangtze River Basin: A comparison and summary.

The nature of sediment dissolved organic matter (SDOM) can reflect the environmental background, nutritional status and human activities and is an important part of lakes. The differences in the binding capacity of heavy metals and organic matter in lake sediments with different trophic states at the catchment scale and the mechanism of the differences in binding are still unclear. To solve this problem, we collected bulk SDOMs (< 0.

Biotic and abiotic controls on sediment carbon dioxide and methane fluxes under short-term experimental warming.

Due to the differences in biotic and abiotic factors between soil and sediments, the predicted linkages between biotic and abiotic factors and soil carbon dioxide (CO) and methane (CH) fluxes under warming may not be suitable for sediments. Additionally, the combination of biotic and abiotic factors which determines sediment temperature-dependent CO and CH fluxes remains unresolved. To address this issue, different types of sediments (including lake, small river and pond sediments) collected from 30 sites across the Yangtze River Basin were incubated under short-term experimental warming.

Multi-spectroscopic investigation of the molecular weight distribution and copper binding ability of dissolved organic matter in Dongping Lake, China.

The properties and metal-binding abilities of dissolved organic matter (DOM) rely on its molecular weight (MW) structure. In this study, the spatial differences of DOM in compositions, MW structures, and binding mechanisms with copper (Cu) in Dongping Lake were investigated by applying excitation-emission matrix combining parallel factor analysis (EEM-PARAFAC), synchronous fluorescence (SF) spectra, two-dimensional correlation spectra (2D-COS), and Fourier transform infrared (FTIR) spectra. The EDOM for the entrance of the Dawen River and PDOM for the macrophyte-dominated region were divided from DOM of Dongping Lake based on hierarchical clustering analysis (HCA) and principal component analysis (PCA) and were size-fractioned into MW < 500 kDa and <100 kDa fractions.

Characterizing the interactions between sediment dissolved organic matter and zinc using multispectroscopic techniques.

Sediment dissolved organic matter (DOM) was collected in November 2018 from Lake Dongping, China. The lake was divided into the entrance of the Dawen River, the open region of the lake, the tourism district and the macrophyte-dominated region based on principal component analysis (PCA) of 9 DOM-related parameters. Multispectroscopic tools were used to investigate the binding of zinc (Zn) with four kinds of DOM collected from the entrance of the Dawen River (EDOM), the open area of the lake (ODOM), the macrophyte-dominated area (mainly dominated by Potamogeton crispus L.

Characteristics and influencing factors of hydrochemistry and dissolved organic matter in typical karst water system.

The unique hydrogeological conditions of karst area make the groundwater react rapidly to rainfall events, which makes the groundwater more susceptible to anthropogenic pollutions. The current study based on a combined excitation-emission matrix fluorescence spectroscopy and parallel factor analysis (EEM-PARAFAC) and geochemical-statistical investigation of water samples from the karst water system in Xintian County, Hunan Province, China, gives crucial information about the principal factors influencing karst water hydrochemistry and dissolved organic matter (DOM). The analyzed data revealed that both surface water and descending spring samples were within the Ca-Mg-HCO water type and dominated by humic-like fluorophore, and well water samples were within both the Ca-Mg-HCO and Na-HCO water types and controlled by protein-like fluorophore.

Influence of land use and rainfall on the optical properties of dissolved organic matter in a key drinking water reservoir in China.

The concentration, source and composition of dissolved organic matter (DOM) in aquatic ecosystems are associated with land use and hydrological connectivity between terrestrial and aquatic systems. However, direct evidence of the effects of rainfall and land use on the variability of DOM in aquatic ecosystems is very limited. In this study, chromophoric DOM (CDOM) absorption and fluorescence spectroscopy were used to elucidate how rainfall and land use affect the variability of CDOM in the watershed of Lake Tianmu, a key drinking water reservoir in the Yangtze River Delta.

[Temporal-spatial Distribution of Nitrogen and Phosphorus Nutrients in Lake Taihu Based on Geostatistical Analysis].

It is of great significance to investigate the spatio-temporal variation in nitrogen and phosphorus nutrients as a mechanism for controlling the sudden increase of algae in eutrophic water. Based on the geostatistical analysis, we studied the sources and occurring forms of nitrogen and phosphorus in different areas of Lake Taihu-a large shallow and eutrophic lake in China. We also examined the spatial distribution of the type of nutrient restriction and its reason by monitoring the sites seasonally from August 2014 to May 2015.

[Fluorescence Characteristics and Environmental Significance of Organic Matter in the Northern Part of Lake Taihu in Spring and Winter].

Organic matter (OM), rich in carbon, nitrogen, phosphorus and other biogenic elements, has numerous geochemical and ecological functions in all kinds of water bodies, and is highly valued in ecological studies of both marine and inland environments. The formation, transformation, and fate of OM, and its accompanying nutrient regeneration process are key links in the biogeochemical cycling of nutrients in aquatic ecosystems. Furthermore OM, as a provider of nutrients, also plays a very significant role during the outbreak of algal blooms in inland lakes.

[Fluorescent Characteristics and Environmental Significance of Particulate Organic Matter in Lake Taihu, China].

Thirty-two samples were collected from eight typical areas in Lake Taihu. Three-dimensional excitation-emission matrix fluorescence spectra (EEMs) and a parallel factor analysis (PARAFAC) were applied to investigate the fluorescence properties, the sources, and environmental significance of particulate organic matter (POM) from the overlying water in Lake Taihu in summer. Differences in fluorescence characteristics between POM and DOM (dissolved organic matter), and that in POM between the grass lake and the algal lake were further examined.