Within-lake variability and environmental controls of sediment denitrification and associated N2O production in a shallow eutrophic lake

Abstract

Excess nitrogen (N) in lakes may lead to eutrophication and many attendant environmental problems such as water quality decline and loss of aquatic biodiversity. Denitrification in lake sediments can alleviate the effects of eutrophication through removal of N to the atmosphere as N2O and N2. However, N2O contributes to the greenhouse effect and global warming. In this study, we measured three denitrification parameters (i.e., potential denitrification rate, unamended denitrification rate and net N2O production rate) in surface sediments which were collected from 7 sub-lakes of the Lake Donghu, one of the most eutrophic lakes in China. The results showed that a range of water quality and sediment characteristics (e.g., total N and total phosphorus) varied significantly among sub-lakes. The unamended denitrification rate varied between 0.51 and 26.0 ng N g-1 h-1 , while the N2O production rate ranged from less than 0 to 1.68 ng N g-1 h-1. However, there was no significant difference among the sub-lakes in these denitrification parameters. The unamended denitrification rate was positively related to the water NO3concentration and sediment moisture and bulk density. The findings of the present study suggest that sediments in eutrophic lakes can remove large quantities of N through denitrification and may become a significant source of N2O if the N input is maintained or to increase.

Has Submerged Vegetation Loss Altered Sediment Denitrification, N2O Production, and Denitrifying Microbial Communities in Subtropical Lakes?

“…In some cases, C availability is considered as one of the most important factor regulating the sediment denitrification rates . Consistent with previous work conducted in the Yangtze River basin (e.g., Yao et al, 2016), our study found that there was no significant relationship between denitrification rates and C concentrations in water or sediments (Table 3). This result can be due to the high concentration of C in sediments and suggests that sediment denitrification rates of Yangtze lakes are not limited by the availability of C.…”

“…However, this significant correlation was not detected in macrophyte‐free lakes. The positive relationship between N content and denitrification rate has been frequently observed, because NO 3 − is the terminal electron receptor of denitrification process and a high NO 3 − level in lake water can directly enhance the sediment denitrification rates (Garcı́a‐Ruiz et al, ; Liu et al, ; Yao et al, ). In macrophyte‐free lakes, background denitrification rate increased with increasing sediment moisture (Table ).…”

“…In contrast to biological immobilization and sediment storage, sediment denitrification is the dominant N removal pathway in lake ecosystems and results in the permanent removal of N through the conversion of nitrate (NO 3 − ) to nitrous oxide (N 2 O) and dinitrogen (N 2 ) gases (Bettez & Groffman, ). Denitrification in lakes can be significantly influenced by many local abiotic and biotic factors, including water chemistry, sediment properties, and aquatic plant communities (Bruesewitz et al, ; Veraart et al, ; Yao et al, ).…”

“…Denitrification in lakes can be significantly influenced by many local abiotic and biotic factors, including water chemistry, sediment properties, and aquatic plant communities Veraart et al, 2011;Yao et al, 2016).…”

The roles of environmental variation and spatial distance in explaining diversity and biogeography of soil denitrifying communities in remote Tibetan wetlands

“…Excess N is directly linked to numerous environmental issues at different scales, including climate change, N deposition, river and lake acidification, water quality deterioration, forest productivity decline, and biodiversity loss (Driscoll et al 2001;Magill et al 2004;Compton et al 2011;. Denitrification is known to be the most important N removal process, converting nitrate (NO 3 -) to nitrous oxide (N 2 O) and dinitrogen (N 2 ), which are then released into the atmosphere (Bettez and Groffman, 2012;Yao et al 2016;Xiong et al 2017). It has been estimated that global terrestrial, freshwater, and marine ecosystems can remove approximately 313 Tg N annually through the denitrification process (Seitzinger et al 2006).…”