Sedimentary nitrogen fractions and source assignment from different inflows to a receiving lake

Abstract

The spatial distribution of the sediment nitrogen in ten typical estuaries of Lake Taihu was determined. A simple quantitative estimation model and principal component analysis (PCA) method were applied to find the source and major factors of estuarine sediment nitrogen loading. The average concentrations of total nitrogen (TN), organic nitrogen (Org-N), ammonium nitrogen and nitrate-nitrogen in the sediments of the ten estuaries were 1315.5, 1220.1, 82.53 and 6.45 mg/kg, with the organic fraction dominating. Results showed a significant difference for the TN concentration in sediments of different estuaries, which was mainly caused by geographical location, land use type and vegetation restoration measures. An important result was that sediment nitrogen in 80% of the estuaries was mainly originated from autochthonous algae and presettled organic matter, although there has been continuous pollution input from inflow rivers. The source estimation results found that the autochthonous aquaculture excretion, algae and hydrophyte debris and buried biodetritus accounted for 58.9% of the total nitrogen loading, which dominated the nitrogen sources compared with the pollution input. In addition, the PCA method was used to find that phosphorus loading and redox conditions were the major limiting factors affecting the distribution of inorganic and , respectively.

Effects of algae and hydrophytes on the inorganic phosphorus pool of shallow hypereutrophic Lake Taihu

“…The re-distribution of nutrients in lake ecosystems is largely determined by the re-suspension process. Higher water content represents a strong possibility of nutrient releasing to the overlying water (Li et al 2020). The WC ranged from 30.40 to 58.64% in the two areas, and the average WC value in East Lake Taihu was larger than Zhushan Bay (Table 1).…”

“…The sediment water content (WC) is the indication of sediment compaction conditions, which determines the re-suspension of sediment nutrients (Li et al 2020). The re-distribution of nutrients in lake ecosystems is largely determined by the re-suspension process.…”

Novel sediment source fingerprinting quantifying erosion-induced total nitrogen and total phosphorus outputs from an intensive agricultural catchment, North China

“…Although some studies have reported on speciation and distribution of the nutrients (N and P) in river/lake sediment (Li et al, 2012;Shen et al, 2021), the effect of agricultural J o u r n a l P r e -p r o o f intensification on historical nutrient dynamics and source in the sediments (Ni et al, 2015), estimating the flux loads and sources of total N (TN) and total P (TP) by hydrologic surveys and an experimental simulation of suspended sediment (Wang et al, 2017), finding the source and major factors of estuarine sediment N loading by model (Li et al, 2020a), identifying recent sources and fate of sedimentary N in the Baltic Sea based on organic matter elemental composition and N and carbon (C) stable isotopes ratios (Winogradow &Pempkowiak, 2020), and identifying sources and cycling of P in the sediment of inflow rivers (Wang et al, 2021), no information is available about quantitively identifying N and P pollutants-based sediment sources under different land management.…”