酸性濕沈降對農作物影響之探討

Abstract

大氣之雨、霧、雪、露等降水型態在PH<5.6時，被稱爲酸性濕沈降，其中較常見者爲酸雨及酸霧兩種。雖然自然界可能產生致酸物質，但對濕沈降的酸性貢獻不大，主要來源仍爲石化燃料燃燒後之衍生物。目前酸性濕沈降物質的酸鹼値有逐漸下降的趨勢，對全球環境、生態的破壞無遠弗屆，而且日益嚴重。農作物生育期間，植株長期暴露於酸性濕沈降之下將造成傷害，包括葉、莖、花、果實等外觀的損傷、壞疽，生理生化反應的失衡，以及産量、品質的降低。然而，也有部份報告指出酸性濕沈降對農作物的傷害並不明顯，甚至有助於作物生長良好。上述歧異結果之原因，乃由於作物種類、品種（系）、發育時期、表皮特性、受害時間及酸性強度等因素造成，因此釐清這些因素之間的關係，有助於建立正確合適的防制策略。 When reacted with acidic gases or anionic species, pH of water molecules in the air may fall below 5.6 before ’dropping’ down to the ground and is called acidic wet deposition or acid precipitation. Among many forms of precipitation, acid rain and acidic fog are of common awareness. The major sources of these acidic particles are attributed to the burning of fossil oil rather than the natural occurrences. In recent years, acidic precipitation becomes a serious problem to ecosystem and environment in many regions of the world, especially in the industrialized areas including Taiwan. During the growth period of a crop, injuries may occur to leaf, stem, flower and fruit when exposed periodically to acid precipitation. Plants are vulnerable to acid deposition depending on species, variety, growth status, characters of leaf surface, and the nature and treatment of acidic solutions. Quite a few efforts have been made still much experiment needs to be conducted to assess the appropriate strategy for controlling damages caused by acid precipitation.