| Introduction:The Baltic Sea in northern Europe is semi-enclosed and the largest brackish water body in the world which links the continents to the ocean by means of fresh water (Neumann,T.2000,Omstedt, et al. 2012 and Thang, et al 2013).TheBaltic is dominated by cultivated landscape in temperate climate, and by evergreen coniferous forest and diverse wetlands in the north.The marine environment is complex; there are many interactions taking place between e.g. anthropogenic nutrient loads, physical, chemical and biological processes.The Baltic basin receives a large amount of dissolved organic carbon (DOC); carbon mostly originating from terrestrial sources transported frorm the surrounding river runoff (Omstedt, et al.2012).It is assumed that DOC degradation is more susceptible to marine environment because saline water offer favored physical and chemical environment compared to fresh water(Wikner, et al.1999).But we know very little about the effect of salinity on DOC reactivity.Few studies demonstrated that nutrients, salinity,bacteria, and pH are limiting factors of DOC degradation but we know even less about the interaction effects between salinity and other factors that are mentioned,on DOC bio-reactivity ( Zweifel, 1993, Milles, et al, 2008,HELCO, 2012).A better understanding of DOC bio-reactivity is needed in order to predict the effect of the of the terrestrial DOC on the oxygen concentrations in the coastal zone of the Baltic Sea.This research work will assess short term DOC bio-reactivity considering pH, salinity,bacteria, and nutrients concentration of Baltic Sea.
Objectives: The main objective of this study is- Quantify the effects of nutrient concentrations (N and P), pH, salinity and bacteria on freshwater and estuarine systems on short term DOC bio-reactivity, in the Baltic Sea.
Hypothesis
Hypothesis 1: High P and N load affect positively bacterial activity which increases the DOC degradation.
Hypothesis 2: Low pH values (more acidic condition) increases the DOC degradation.
Hypothesis 3: A higher salinity condition is related to a high DOC degradation rate.
Hypothesis 4: DOC reactivity is higher in the estuarine environments compare to freshwater environments.
Method:
Sampling: Water sample will be collected from 5-10 selected rivers considering agricultural field, urban area, forest area, mires etc.The pH, salinity and temperature will be measured with standard equipment in the sample locations.
DOC Reactivity Analysis: Collected water samples will be filtered through a 1 µm net to remove larger particles. To assess DOC reactivity, the bacterial consumption of DOC will be measured in experiments with Baltic Sea micro organisms, where pH, salinity and nutrient concentrations will be manipulated. Nutrients will be added to increase the concentration of N and P separately and combination of both (N+P) will use with water sample (Jansson, et al., 1996).Experiment will be performed in room temperature (20C) incubation and in total darkness (Hopkinson, et al., 2002).Statistical method ANOVA will be applied.
Expected Result: An increasing salinity, bacterial production, nutrients concentrations and lowering pH increased DOC bio- reactivity which in turn lead to more anoxic conditions in the Baltic Sea. |