Abstract:
Muthurajwela marsh situated along the west coast of Sri Lanka is being highly exploited by
the industries to dump their waste. According to the literature a high organic matter content in
the marsh (>30%) is having a linear relationship with the soil cation exchange capacity
(CEC), making industries to consider the marsh a potential wasteland with a high capacity to
hold heavy metal cations. The high CEC of marsh is capable to act as a buffer preventing the
surrounding ground water becoming acidic even though the organic soils are acidic.
With the accelerated development around the area, various anthropogenic activities have been
affecting the moisture content of the soil which may alter the quality of the marsh. In an
attempt to investigate the effect of the changing moisture content on the soil properties of the
marsh, a preliminary study is been conducted at certain areas in the periphery of the
Muthurajawela sanctuary. The observed results are as follows; moisture content of 17.64% to
168.71% (by dry weight) and 36.63% to 84.31% (by wet weight), organic matter content of
5.06% to 57.89% (by dry weight), total CEC of 96 to 696 meq/100g soil, soluble soil pH of
2.10 to 7.91 and exchangeable soil pH of 2.08 to 7.26. Samples from the sites that had very
high moisture levels showed higher organic matter contents, low pH values and very high
CEC. As the soil moisture decreased, the organic matter levels and the total CEC decreased
while the soil pH increased according to the study so far.
The study implicates that the moisture content has a significant influence on the organic
matter content of the marsh soil and hence is important in monitoring the quality of the
marsh. Reduction of the soil moisture due to anthropogenic activities is therefore suggested to
be directly affecting the continuity of the organic nature of the soil. Hence the cation
exchange capacity and other properties of the soil would be altered making long-term loss of
soil moisture putting the wetland system at the risk of losing its ecological performance.
Therefore the Muthurajawela marsh needs strict conservation.
