Using sedimentary phosphorus/nitrogen as indicators of shallow lake eutrophication: concentrations or accumulation fluxes

Abstract

Inland lakes have been suffering from eutrophication and nutrient sedimentation plays an important role in the eutrophication history of shallow lakes. Sedimentation processes and accumulation fluxes of nutrients were studied in the Central Lake zone (CL) of Taihu Lake (Taihu), a large shallow lake in China, with multisampling by the 210 Pb dating method and determination of sediment mass accumulation rates (MARs) and sedimentary phosphorus, nitrogen, carbon and iron concentrations, in order to track the anthropogenic eutrophication history of Taihu and to explore the available sedimentary indicators of trophic states of shallow lakes. It was found that MARs in CL varied from 0.016-0.048 to 0.078-0.339 g cm -2 a -1 with a turning point in 1980, corresponding to the rapid developing trend of society and economy in Taihu Basin after 1980. Rather than sedimentary nutrient concentrations, nutrient accumulation fluxes increased by 0.6-7.1-fold (P) and 2.3-12.2-fold (N) acting as paleolimnological indicators for the eutrophication explosion of Taihu since 1980. Yearly elevated TN in sediment cores and more greatly increased N accumulation fluxes than P with 350-1906 t a -1 in recent years (2009)(2010)(2011)(2012), suggest that nitrogen should get more attention to control for eutrophication risk of Taihu in future. There were spatial differences in nutrient accumulation fluxes and in weights of MARs and sedimentary nutrient concentrations contributing to the nutrient accumulation fluxes in CL. TOC in modern sediment (\1 m), responsible for increments in sedimentary P/Fe and TN and nutrient accumulation fluxes, acts as a key factor for controlling nutrient sedimentation and needs studies further for nutrient mass balance theory in Taihu.

Vertical records of sedimentary PAHs and their freely dissolved fractions in porewater profiles from the northern bays of Taihu Lake, Eastern China

“…The method and procedure of sediment dating was presented in our previous publication. 21 In summary, the Fig. S1 † and the accumulation uxes of SPAHs were calculated with the equation described in Table S2.…”

Suspended solids induce increasing microbial ammonium recycling along the river‐estuary continuum of the Yangtze River

“…Nitrogen (N) is an essential nutrient for organisms and the excessive inputs of N have led to serious eutrophication and frequent harmful algal blooms in aquatic systems (Di et al, 2015; Diaz & Rosenberg, 2008). As an important reduced form of N, NH 4 + requires the least energy for the uptake of phytoplankton and bacteria, and thus commonly low water column concentrations are observed when the primary production is high (Gardner et al, 2004; Paerl et al, 2011).…”

Holocene foraminiferal and geochemical records in the coastal karst dolines of Cres Island, Croatia

“…For example, the C/N ratio can be useful in the determination of organic matter provenance (MEY-ERS, 1994;MEYERS, 2003;LAMB et al, 2006). Nitrogen (N) and phosphorus (P) concentrations coupled with total organic carbon (TOC) content are frequently used as indicators of nutrient availability and primary productivity (MEYERS, 1997;DE-LANEY, 1998;DI et al, 2015). Application of molybdenium (Mo) as a proxy for redox conditions is also common (PEDERSEN, 1989;CRUSIUS et al, 1996;CALVERT & PEDERSEN, 1993;ALGEO & LYONS, 2006;SCHOLZ et al, 2017).…”