VARIATION OF SOIL, WATER QUALITY AND IMPACTS ON BIODIVERSITY IN XUAN THUY RAMSAR SITE

Soil and water quality are important environmental condition for biodiversity development in Xuan Thuy Ramsar site. This research is carry out in order to assess the variation of some parameters of soil and water quality and its impacts on biodiversity, especially flora in there. Investigating and survey methods and samples analysing are implement to meet with purposes of research during 3 years (period 2011-2013). The result of research showed that the water quality in two main rivers (Tra and Vop rivers) had a freshening trend for the duration of the study, beginning with 1.53% in 2011 the average salinity fell to 0.78% and 0.35% in 2012 and 2013, respectively. Biological decomposition of organic matters and eutrophication phenomena increased remarkably in these years (average DO in 2011 was 8.03mgO2.L -1 , decreased to 4.59mgO2.L -1 in 2013; while average COD increased 191.22% by 2011 and average BOD increased 248.56% by 2011). Nutrient content in the soil which is sampled in 2013 is slightly decrease than that in 2012 (from 886.00 and 535.00 (2012), Nitrogen content (N) reduced to 758.72 and 527.7mg.Kg -1 (2013) in Con Ngan and Con Lu respectively; with the similar trend, Photsphas content (P) has already shown off the downward trend when decresed from 563.38 and 438.94 (2012) to 446.22 and 415.80 mg.Kg -1 (2013) in Con Ngan and Con Lu respectively) and the scale of low nutrient soil tend to increase. The negatively changing environment has significant impacts on floating flora and fauna cause the variation of area and number of species in mangrove ecosystem as well as the biodiversity of Ramsar site. The study results will be the important baseline and helpful to develop solutions on sustainable management for Xuan Thuy Ramsar site.