Vertical distribution and release characteristics of nitrogen fractions in sediments in the estuaries of Dianchi Lake, China

Abstract

Columnar sediment samples were collected from five representative estuaries of Dianchi Lake, China. And the vertical distribution of each fraction of nitrogen (IEF-N, CF-N, IMOF-N, OSF-N) were tested. The results showed that the TN content in sediments from areas A, B, C, D and E gradually decreased with depth between 0 and 15 cm, then sharply decreased with depth between 15 and 30 cm and stabilized at depth below 30 cm, indicating the exogenous input of N in these areas has not been controlled effectively. The proportion of TN occupied by various N fractions in the sediments ranked as follows: OSF-N > IMOF > CF-N > IEF-N. Correlation analysis results showed both IEF-N and IMOF-N were significantly correlated with the content of TFe 2 O 3 + MnO + Al 2 O 3 in deeper sediments, while no correlation in superficial sediments. The areas A and B have extremely high release risks for N in superficial sediments. However, the N in the sediments of areas C, D and E were in relative equilibrium with the overlying water, indicating release potential risk was relatively low.

The Hydraulic Driving Mechanisms of Cyanobacteria Accumulation and the Effects of Flow Pattern on Ecological Restoration in Lake Dianchi Caohai

“…The water quality and eutrophication status of a lake will deteriorate when the pollution loading into the lake exceeds the carrying capacity of the water environment [12,13]. Moreover, climate changes accompanied by rising air temperatures and changes in wind speed and direction can indirectly affect the water temperature structures of lakes and change the hydrodynamic conditions in shallow lakes to accelerate the occurrence of water pollution and toxic cyanobacterial blooms, which are the key characteristics of eutrophication [3,10,14,15]. All water quality problems will degrade the stability of lake ecosystems and landscape values, reduce water functions, and lead to the reduction in available water resources, even causing irreversible harm to human health [16,17,18,19].…”

“…Since China’s economic reform and its integration with the world economy in the early 1980s, the country experienced a dramatic change regarding its social development and economy. Moreover, the natural environment in China suffered from accelerated lake eutrophication, and the eutrophication in Lake Dianchi is considered the most serious [15,35]. By the end of the 1990s, more than 70% of the lakes were considered eutrophic, and this phenomenon has become even more severe in recent years [36,37].…”

Vertical distribution and release characteristics of phosphorus forms in the sediments from the river inflow area of Dianchi Lake, China

“…In addition, the corresponding overlying water was also collected and the parameters including temperature, pH value, oxidation-reduction potential (E h ), dissolved oxygen (DO) were measured in the field. The properties of those studied sediments and overlying water were also reported in our previous studies [15]. The TN, TP, and soluble reactive P (SRP) within the overlying water were measured in the laboratory [16].…”

Characteristics and Pollution Contribution of the Internal Nitrogen Release From the Sediments in the Dahekou Reservoir in Inner Mongolia

“…The contribution of nitrogen to water eutrophication has increased significant interest among scientists, and a large number of studies have confirmed that nitrogen is another key limiting factor in the water eutrophication of freshwater lakes (Han et al, 2014;Shan et al, 2015). At present, most scholars have mainly focused on the influences of the lake water body sediment nitrogen composition, occurrence forms, spatial distribution, diffusion flux, and interface structure on the contribution to the water environment (Pennuto et al, 2014;Yang et al, 2017). Conversely, little research has been conducted on the nitrogen release from sediments, which is affected by changes in the overlying water environment.…”