Bias and association of sediment organic matter source apportionment indicators: A case study in a eutrophic Lake Chaohu, China

Abstract

The sources of sediment organic matter (SOM) could be explained by various indicators. To test their biases and associations, the present study determined multiple indicators for SOM source apportionment, including elemental analysis (carbon and nitrogen, and their stable isotope δC and δN), n-alkanes compositions as well as derivative indicators (e.g., terrigenous to aquatic ratio), and carbon isotopes of n-alkane in Lake Chaohu, a eutrophic lake. The spatial variation of anthropogenic effects could be revealed by SOM elemental variations. The n-alkanes of all samples had a bimodal distribution with the 1st peak at n-alkane with 17 carbons (C17) and the 2nd predominant peak at C29. The parity advantage index of n-alkanes indicated that the sediments had mixed characteristics of both endogenous and terrigenous sources. Some n-alkanes indicators also revealed eutrophication characteristics of dominant algae in Lake Chaohu. SOM received a mixed contribution of plankton (I), low-latitude terrestrial high-grade plants (II) and microbial material (III) as indicated by isotopic compositions of long-chain n-alkane. Multiport element model (MEM) showed the contribution of self-generated sources of organic matter in Lake Chaohu is >50%, indicating the historic serious eutrophication in Lake Chaohu. The main sources of SOM in the eastern part of the lake were algae and terrestrial input, with little input from microbes, and the contribution from algae decreased from west to east. The multiple indicators' judgment by MEM and principle component analysis (PCA) was of ecological significance and proposed because they offered scientific tools for disclosing the historic variations of SOM as well as their sources.

Dissolved carbon in a large variety of lakes across five limnetic regions in China

“…4a. Algal bloom combined with sediment re-suspension caused by strong winds may explain the biased relationship between DOC and DIC in these lakes, as it was found previously by Xu et al (2017). However, when the samples in the circle in Fig.…”

Caracterización Físico-Química De Los Sedimentos Del Humedal Laguna Bella en La Selva De Huánuco, Perú

“…Las fuentes de materia orgánica sedimentaria pueden dividirse en endógenas y exógenas. La primera proviene principalmente de bacterias lacustres, algas, plantas acuáticas y otros grandes organismos acuáticos, y la segunda proviene principalmente de plantas terrestres de alto grado y de actividades humanas (Xu et al, 2017).…”

“…Los sedimentos, al ser muy sensibles a los cambios en el ambiente, retienen evidencia de procesos de deposición de materiales derivados de factores exógenos como el clima, la erosión, la meteorización y la evolución de la flora y fauna; y endógenas como la tectónica, la actividad volcánica, las fluctuaciones geomagnéticas y otros (Herrera, 2011;Xu et al, 2017); asimismo, los depósitos de sedimentos en los lagos funcionan bien sea como fuente o como reserva de muchos de los nutrientes (Ramírez & Noreña, 2004), por lo que sus estudios deben ser incluidos en la caracterización de los sedimentos de humedales.…”

Spatiotemporal Variations in Seston C:N:P Stoichiometry in a Large Eutrophic Floodplain Lake (Lake Taihu): Do the Sources of Seston Explain Stoichiometric Flexibility?

“…This inconsistency suggests that the seston in estuary sites during the senescence season were not fresh materials from terrestrial plants. These sestons have been reworked by microbes and maybe from erosion soils [29]. Yet the precise composition of different sources in the seston pool could not be fully resolved by n-alkane proxies alone.…”