Hubungan Nitrat (No3) dan Nitrit (No2) Terhadap Keanekaragaman Fitoplankton di Sungai Belawan

Abstract

Phytoplankton diversity and nitrate nitrite content influence the water quality conditions of the Belawan River. Community activities such as the disposal of organic, inorganic, domestic waste and fertilizer runoff also corrosive materials cause a decrease of the water quality. This research aims to determine the diversity of phytoplankton a d toanalyze the relationship between nitrate and nitrite content as well as physico-chemical factors to the phytoplankton diversity in the Belawan River. This research used a purposive sampling method by determining 5 stations based on community activities (station 1 at Salam Tani Village, Pancur Batu District and station 5 at Sicanang Village, Medan Belawan District). Data analysis included the nitrate and nitrite content, the phytoplankton identification, the abundance values, the relative abundance, the frequency of presence, the diversity, the uniformity of the phytoplankton, and also the physico-chemical factors, as well as the correlation analysis of the relationship between nitrate and nitrite content and physico-chemical factors with phytoplankton diversity. The nitrate content obtained from 5 stations in the Belawan River ranged from 7.6 to 11.2 mg/l while the nitrite content ranged from 0.02 to 0.28 mg/l. The number of phytoplankton found from all stations was come from 30 genera, 25 families and 5 classes. The abundance values ranged from 26.4 to 72 mg/l with the highest found at station 5. The highest diversity index (H') value was obtained at station 5 (2.38) with medium diversity criteria. The highest uniformity index (E) value was obtained at stations 4 and 5 with values were 6.9 categorized by high uniformity. The measurements of the physico-chemical factors and the nitrate nitrite content in the Belawan River complied with standards generally, especially stations 1 and 2, with exception in stations 3, 4 and 5 which exceed river water quality standards, especially DO and BOD5. The results of the correlation analysis of the relationship between phytoplankton diversity and nitrate and nitrite content as well as physico-chemical factors show a very strong influence, especially on nitrate levels, temperature, pH, DO, BOD5 and COD.