QUALITY MEASUREMENTS IN CLOUD WATER, RAIN, THROUGHFALL, AND STREAM WATER, AT HORTON PLAINS

Abstract

Die-back of natural forests in the Horton Plains has been of some concern inrecent times. One of the possible causes is atmospheric pollution. Since clouds(jog) carry greater amounts of pollutants than rain, an assessment was made ofboth rain and cloud water quality, as well as that of throughfall and streamwater. Samples were collected and analysed at weekly intervals from November1995 to May 1996. They were tested for pH, electrical conductivity (EC), nitratenitrogen (NOrN), ammonium nitrogen (NHrN) and sulphate sulphur (,'-,·(Jr-S).Plastic buckets were used to collect rain water and throughfall. A collector wasdesigned and constructed to collect cloud water. The average pH of cloud waterlVas 5.0 and the values as low as 3.9 was observed during certain periods ..According to the literature, this latter high acidity could be injurious, burningtender leaves. The highest concentrations of NOrN, NH4-N, and S(Jr-S incloud water were 10.23, 5.04 and 9.40 mg/litre respectively; vet:y IIIl1ch higherthan those of the rain water. These pollutant levels and high acidity may causestress on the plants. The concentration (if chemicals is also high in thethroughfall. However, the soil acts as a buffer and provides good quality waterto the streams, as shown by the vet:y low concentration of chemicals there.