Sulfur Development in the Water-Sediment System of the Algae Accumulation Embay Area in Lake Taihu

Abstract

Sulfur development in water-sediment systems is closely related to eutrophication and harmful algae blooms (HABs). However, the development of sulfur in water-sediment systems during heavy algae accumulation still remains unclear, especially in hyper-eutrophic shallow lakes. In this study, a quarterly field investigation was carried out for a year in the algae accumulated embay area of Lake Taihu, accompanied by a short-term laboratory experiment on algae accumulation. The results show that hydrogen sulfide and methanethiol dominated the volatile sulfur compounds (VSCs) in the water during non-accumulation seasons, whereas the concentrations of dimethyl sulfides increased during heavy algae accumulation, both in the field and the laboratory. An increase in the acid volatile sulfide (AVS) in the surface sediments was also discovered together with the increase in dimethyl sulfides. The depletion of oxygen in the overlying water and sediment-water interface during the heavy algae accumulation and decomposition was found to be closely related to both the increase in VSCs in the overlying water and increase in AVS in the sediment. The increased concentrations of these reductive sulfocompounds might aggravate the eutrophication and HABs and should be given more consideration in future eutrophication control plans for lakes.2 of 15 of P to phytoplankton increases when the release of P from the sediments increases under anoxic conditions [20,21]; this usually occurs during algal blooms [22][23][24]. The formation of sulfides facilitates the formation of ferrous sulfide (FeS) and the release of P from the sediments [14], aggravating eutrophication and HABs in the water. This process usually takes place in freshwater sediments because of the low sulfate concentration of freshwater [14,25]. However, in the overlying water, another problem is the formation of volatile sulfur compounds (VSCs) during HABs. Various VSCs, including hydrogen sulfide (H 2 S), methanethiol (MTL), dimethyl sulfide (DMS), dimethyl disulfide (DMDS), and dimethyl trisulfide (DMTS), have been detected during HABs [26][27][28]. MTL, DMS, DMDS, and DMTS are also known as volatile organic sulfur compounds (VOSCs). The high concentration of VSCs causes freshwater sites to become more odorous [29,30]. In 2007, a crisis occurred in Wuxi City, China, resulting from the accumulation of algae in Lake Taihu, the city's drinking water source, in which the tap water turned black and became odorous [31,32]. High levels of VSCs were found to be responsible for the crisis [31,32]. VSCs are difficult to remove from drinking water sources through conventional techniques due to the high cost and the residual of the processes required [33]. Therefore, it is imperative to understand the origin and formation of VSCs in drinking water sources such as lakes and reservoirs.Although the formation and migration of sulfides and VSCs have been noted and studied worldwide [28,34], the development of these compounds in the water and sediment systems still remains unclear, especially...

Trace Element Patterns in Shells of Mussels (Bivalvia) Allow to Distinguish between Fresh- and Brackish-Water Coastal Environments of the Subarctic and Boreal Zone

“…Therefore, factor 1 was directly related to the bottom substrate in biotopes inhabited by studied mussels' species and it allowed distinguishing between marine and freshwater mollusk species according to their habitat preferences (Figure S9B). Factor 2 can be related to the water chemistry at the water-sediment interface, due to the presence of sulfur compounds in such settings (i.e., [33,76]).…”

CS2 increasing CH4-derived carbon emissions and active microbial diversity in lake sediments

“…Volatile sulfur compounds (VSCs) widely exist in terrestrial aquatic systems and are mainly produced from the degradation of organic matter in sediments, which is usually accompanied with CH4 emission (Liu et al, 2019). The VSCs are mainly in the form of hydrogen sulfide (H2S), methanethiol (CH3SH), carbon disulfide (CS2), dimethyl sulfide ((CH3)2S), and dimethyl disulfide ((CH3)2S2) (Bentley and Chasteen, 2004;Wu et al, 2010).…”

“…The VSCs are mainly in the form of hydrogen sulfide (H2S), methanethiol (CH3SH), carbon disulfide (CS2), dimethyl sulfide ((CH3)2S), and dimethyl disulfide ((CH3)2S2) (Bentley and Chasteen, 2004;Wu et al, 2010). H2S and CH3SH can be detected throughout the annual cycle in the water of Lake Taihu, China, ranging from 0.6-882.4 and 0.9-156.3 nmol L -1 , respectively (Liu et al, 2019). (CH3)2S level is extremely high (up to 6000-7000 nmol L -1 ) in May and July relative to other seasons when algal blooms form (Reese and Anderson, 2009).…”