Interactions between microbial degradation of sedimentary organic matter and lake hydrodynamics in shallow water bodies: insights from Lake Sarbsko (northern Poland)

Abstract

In this paper we demonstrate spatial and seasonal changes in the pathways of microbial decomposition of organic matter within the surface sediments of Lake Sarbsko, a coastal water body located on the middle Polish-Baltic coast. We studied lake waters and bottom sediments at 11 sampling stations throughout the basin and in different seasons between November 2007 and September 2008. It was established that, in this very productive and shallow lake, microbial activity increases in warmer seasons and ceases during winter. In spring, bacterial activity is fuelled by increased influx of highly reactive planktonic organic matter, which is decomposed via methanogenesis, reduction of NO3 -, SO4 2-, and Fe and Mn oxides. On the other hand, during summer, oxidation processes (mainly oxidation of CH4) tend to predominate. The change from reduction to oxidation is attributed to wind-induced vertical mixing of Lake Sarbsko waters and resuspension of bottom deposits. Degradation of sedimentary organic matter in Lake Sarbsko results in appreciable changes in the pH and the concentrations of red-ox sensitive ions in pore waters, but it has little effect on the chemistry of bottom and surface waters. However, release of PO4 3- from the sediments might be a source of this nutrient in the lake. Internal loading of phosphates in Lake Sarbsko occurs under both oxic/mildly reducing and anoxic conditions

A reconstruction of the palaeohydrological conditions of a flood‐plain: a multi‐proxy study from the Grabia River valley mire, central Poland

“…The organic matter content was obtained via thermal combustion (Heiri et al 2001). Terrigenous (SiO 2ter ) and biogenic (SiO 2biog ) silica were analysed as in Woszczyk et al (2011). The total carbon (TC), total sulphur (TS) and total nitrogen (TN) were determined using a Vario Max elementary analyser (Elementar Analysensysteme).…”

Influence of invasiveAcer negundoleaf litter on benthic microbial abundance and activity in the littoral zone of a temperate river in Lithuania

“…Thus, our results have shown that on average during the study period the higher number of microorganisms and their community activity, with prevailing anaerobic processes, occurred in the littoral sediments of A. negundo leaf litter accumulation zone than in sediments of the river close by riparian native tree location. In shallow zones, anaerobic processes have negative consequences, because they promote the accumulation of fermentation products and other intermediate mineralization compounds (Kuznetsov et al, 1985) as well as benthic phosphorus release (Woszczyk et al, 2011), which, in its turn, may stimulate secondary eutrophication and littoral silting. On the other hand, increasing anaerobic sulfate reduction accelerates the growth of hydrogen sulfide concentration what in the future may have a negative impact on the quantitative and qualitative structure of benthic organisms.…”

Fractionation of metals in the Sa1/2 sediment core from Lake Sarbsko (northern Poland) and its palaeolimnological implications

“…The lake area is 6.5 km 2 and its average depth is 1.4 m with a maximum of 3.5 m in the mid-eastern section of the basin (Figure 1) (Woszczyk et al 2011). The lake is fed by the Chełst River from the east and a few irrigation channels from the south (Figure 1).…”

“…As Lake Sarbsko has no direct connection to the Baltic Sea, freshwater inflow has the greatest influence on the chemical composition of its water, which reveals relatively low chloride concentrations (5.7-97.7 mg L -1 ) (Woszczyk et al, 2011). However, during severe winter storms marine waters may enter the lake via the Łeba river mouth and the Chełst outflow channel slightly raising its salinity.Marine influences in the lake are also reflected in the seasonal variations of the water level, which clearly coincide with fluctuations of the Baltic level (Woszczyk et al 2010).…”

“…Lake Sarbsko is a coastal lake situated in the middle part of the southern Baltic coast, on the Gardno-Łeba coastal plan (northern Bathymetric sketch according to Woszczyk et al (2011).…”