Precipitation Chemistry at the Lienhuachi Experimental Forest in Central Taiwan

蓮華池試驗林雨水化學特性之探討

蕭泓泯(Hung-Min Hsiao) ； 林登秋(Teng-Chiu Lin) ； 黃正良(Jeen-Liang Hwong) ； 黃志堅(Chih-Chien Huang) ； 林能暉(Neng-Huei Lin)

《台灣林業科學》 22卷1期 (2007/03) Pp. 1-13

https://doi.org/10.7075/TJFS.200703.0001

摘要

本文探討2004年10月至2005年9月蓮華池試驗林週採樣的溼沉降化學，取樣期間雨水之體積加權平均pH為4.84，低於酸雨標準5.0，也比十三年前測得的5.51為低。酸性汙染物排放減少以及兩次研究間取樣方式的差異（十年前發表的結果研究為混沉降而本研究研究為濕沉降），皆是pH變化的可能原因。以季節性來看，春、冬的雨水較夏、秋為酸，此一趨勢與台灣其它地區的研究結果相似，一般認為冬季及春季來自大陸的長程傳輸是造成雨水酸度強的重要原因。本研究硫及無機氮的沉降量各約為11.5及13.8 kg ha^(-1)yr^(-1)，此較美國東北部酸沉降量高，而該地區高酸沉降對森林營養循環及健康的影響深受關注。此高酸沉降量對森林生態系的影響有待深入的研究。蓮華池試驗林硫酸根的沉降量與中部數個森林生態系相當，然無機氮的沉降量則比中部其它森林高出相當多，這顯示氮的沉降型態較硫具地方性。蓮華池試驗林附近活躍的農業活動中所使用的含氮肥料，應是本試驗地氮沉降量較中部其它森林生態系高的重要原因。

關鍵字

蓮華池試驗林 ； 酸沉降 ； 硫酸銨 ； 鹽基陽離子

並列摘要

This paper examines weekly wet-only precipitation chemistry in the Lienhuachi Experimental Forest between October 2004 and September 2005. The volume-weighted mean annual pH was 4.84, lower than the Taiwan Environmental Protection Adminstration's criterion for acid rain (pH＜5.0). It was also lower than the value measured 13 years ago at the same site (5.51), despite decreases in the emissions of acidic pollutants over the same period of time. Coincident decreases in the emission of particulate pollutants with high concentrations of acid-neutralizing base cations, as well as differences in the collection methods (wet-only versus bulk precipitation) are possible explanations for the observed differences in precipitation pH. Seasonally, pH was lower in spring and winter than in summer and fall. This pattern is in agreement with many other studies throughout Taiwan and is often attributed to the high contribution of pollutants transported from China in the winter and spring. The rates of S and inorganic N deposition, of 11.5 and 13.8 kg ha-1 yr-1, respectively, were higher than those in the northeastern US where high acid deposition is a major concern in forest nutrient cycling and health. The impacts of such high acidic deposition on forest ecosystems need to be thoroughly examined. The rate of S deposition observed in the Lienhuachi Experimental Forest is similar to those of several other forest ecosystems in central Taiwan, whereas the rate of N deposition at the Lienhuachi Experimental Forest is considerably higher. It appears that areas of high N deposition are more localized than those of S deposition. The application of commercial fertilizers around the Lienhuachi Experimental Forest may explain the observed higher N deposition at our study site compared to other forest ecosystems in central Taiwan.

並列關鍵字

Lienhuachi Experimental Forest ； acid deposition ； ammonium sulfate ； base cation