Effects of water warming on bank filtration: experimental enclosure studies

Abstract

In the context of climate change artificial recharge of groundwater becomes increasingly important. The two main climate change factors affecting ground water recharge performance are water warming and extreme precipitation events with drought and floods. This will strongly influence self-purification processes, indirectly due to changes in the stratification and circulation characteristics of the lake and directly due to the intensification of metabolic processes and biodegradation efficiency, which are responsible for water self-purification.At the study site Lake Tegel, Berlin (Germany), epilimnion water warming of 0.9°C per decade from 1980 to 2007 was detected. Moreover, continuous measurements of temperature for a yearly period from 2010 to 2011 in the openwater epilimnion and littoral zone showed a maximum difference of 5.2°C on a sunny summer day (T Lake,max = 25.3°C, T Air,max = 26.2°C).The present work describes the development and operation of enclosure field experiments conducted to simulate water warming (up to 30°C) and to provide a detailed picture of the processes which occur in the uppermost sediment layers (0-20 cm depth) at a littoral bank site. To illustrate the performance of the enclosure setup with a mean temperature increase of 4.6°C (May-August 2012), microbial activity as well as pore water analysis was examined monthly. Microbial activity was measured by enzymatic TTC-and FDA-methods. Both showed a highly microbial active upper layer down to 5 and 10 cm depth, respectively. However, no clear water warming effects on redox-chemical and microbial activity could be detected.This paper is intended to contribute to an ongoing discussion, if in-situ enclosures enable realistic experimental studies to allow investigations of the Water Resources Management VII 209

How Do Extreme Lake Water Temperatures in Poland Respond to Climate Change?

“…The findings regarding the minimum and maximum changes in LSWT (MinLSWT and MaxLSWT), indicate that different months exhibited varying temperature increases and variability levels within each period. A similar result has been observed in Poland and in other parts of central Europe [29,30,[38][39][40][41][42][43]. The months with the highest variability suggest periods when temperature fluctuations were more pronounced and vice versa, which could be attributed to various factors.…”

The increasing of maximum lake water temperature in lowland lakes of central Europe: case study of the Polish Lakeland

“…Kangur et al (2013) observed an increase in maximum water temperature in the summer period for Lake Peipsi (Estonia/ Russia). In a broader perspective the response of lakes to climatic changes in this part of Europe is similar to many other cases located in different regions of the world (Austin and Colman, 2007;Hampton et al, 2008;Shimoda et al, 2011;Groß-Wittke et al, 2013;Zhong et al, 2016;Haddout et al, 2018). For instance, for the summer period (July-September) the surface water temperature in the Great Lakes in North America experienced a warming trend at a rate of 1.1 °C dec -1 (Austin and Colman, 2007).…”

Climate Change: Water Temperature and Invertebrate Propagation in Drinking-Water Distribution Systems, Effects, and Risk Assessment

“…Increasing water temperatures lead to decreased oxygen concentrations with increasing oxygen consumption by organisms; this means the oxygen balance is worsened, and the risk of anaerobic conditions is raised. Studies on temperature effect on bank filtration were conducted in Lake Tegel, Berlin/Germany using heated enclosures, resulting in a water temperature increase of 5 • C and an increase of sediment temperature of 2-3.5 • C [13]. The redox state of the infiltration zone was changed and characterized by a decline of oxygen concentrations within the interstices.…”

“…Increasing water temperatures of rivers mainly in shallow littoral zones, where groundwater recharge occurs, can impact bank filtration efficiency because water temperature regulates bio-chemical processes. Key factors for bank filtration efficiency are the temperature tolerance of organisms, increasing biomass of interstitial flora and fauna, intensification of turnover of organic carbon, and, as a consequence, increased biochemical consumption of oxygen [13]. In general, we can apply the temperature rate of the reaction rule; this means that an increase of 10 • C leads to biochemical reactions two or three times faster, which corresponds to an increase of 10-20% per • C. In addition, climate change effects, such as long-lasting droughts or flood events, influence bank filtration, but only few studies are available [13,14].…”