The Effect of Acidic Deposition on Nitrate Reductase Activity and Photosynthesis of Hypnum plumaeforme

산성강하물이 털깃털이끼(Hypnum plumaeforme)의 질산 환원효소와 광합성에 미치는 영향

The acidic deposition (wet) was collected at three different locations; representative industrial (Kun-Jang industrial areas), semiindustrial (Kunsan City) and nonindustrial (Daeya areas) region between March, 1991 and June, 1993. Samples were analyzed for major chemical components along with pH. Also the responses of Hypnum filunzaeforme to the acidic deposition adjusted to pH 4.6, 3.6 and 2.6 with 1:4 molar ratio of nitric to sulfuric acid were investigated. Seasonal variation of pH showed the lowest in early spring and the highest in summer. The annual mean concentrations of $S0_4^{2-},\;NO_3^{-}\;and\;NH_4^{+}$ were 2.94 (81.0%), 0.48 (13.2%) and 0.21 (5.78%) mg/l in industrial region and 0.61 (64.21%), 0.25 (26.3%) and 0.9 (9.5%) mg /I in nonindustrial region, respectively. $S0_4^{2-}$ contents of industrial region was 4 times higher than those of nonindustrial region. The ratio of $S0_4^{2-}\;to\;NO_3^{-}$ was 4.75~7.35 in industrial region and 0.69-6.36 in nonindustrial region. The acidic deposition near industrial region was associated with excess ions, expecially $S0_4^{2-}$. Nitrate reductase activity(NRA) of mosses was inhibited by acidic deposition in both regions. The time required for the maximum NRA induction by 2mM $KNO_3$ was shortened in mosses collected from industrial region. Photosynthesis of H. plumaejorme began to decrease with acidic deposition by pH below 4.6, and was completely inhibited at pH 2.6 in both regions. Water potential of mosses treated with acidic deposition was almost constant during 18 days, however after withholding the supply of acidic deposition, it was rapidly decreased.

1991년 3월부터 1993년 6월까지 공단, 준공단 및 비공단지역에서 빗물을 채취하여 pH를 측정하고, 공단과 비공단지역에서 NH4+, NO3-, SO42- 및 전기전도도를 1년동안 측정하였다. 또한 황산과 질산의 1:4로 하여 pH4.6, 3.6 및 2.6으로 조정한 산성강하물이 털깃털이끼의 NRA, 광합성 및 수분포텐셜에 미치는 영향을 조사하였다. 빗물의 pH는 모두 이른 봄에 낮고 여름에 높았으며 공단지역의 낮은 pH는 다량의 이온 특히 SO42-와 관련되었다. 빗물의 SO42-, NO3- 및 NH4+의 월 평균은 공단지역에서 각각 2.94(81.0%), 0.48(13.2%) 및 0.21(5.78%)mg/l 이었고, 비공단지역에서는 각각 0.61(64.21%), 0.25(26.3%) 및 0.9(9.5%)mg/l로 공단지역에서 높았다. 공단지역에서 생육하는 Hypnum plumaeforme의 NRA의 비공단지역에 비하여 공단지역의 것이 낮았고, 산성강하물로 24일 동안 처리한 NRA를 측정한 결과 공통적으로 억제되었다. 공단지역과 비공단지역에서 생육한 식물의 광합성능은 산성강하물 처리후 24일만에 pH3.6에서 각각 85와 80%이상 회복되었으나 pH2.6에서는 66과 56% 회복되었다. 공단과 비공단의 식물체의 수분포텐셜은 산성강하물에 대한 뚜렷한 차이를 보이지 않았으나 단수후 모두 크게 낮아졌다.