山區農業濕沉降化學性質-以石碇為例

Abstract

酸沉降為世界上日益嚴重的環境問題，對於生態造成許多影響，如營養枯竭、森林衰退、土壤和地表水酸化、湖泊和沼澤生物的死亡以及農作物損害，農業上尿素和動物糞便的施用導致大氣中氨的積累，長期的積累可能導致氮沉降增加，對土壤和植物產生不利影響，本研究直接於石碇山區農田內收集濕沉降並分析其化學性質及粗略估算其通量，結果顯示降雨pH值低於5.0佔全部資料53%，霧水pH值低於5.0僅佔全部資料28%，pH值平均也較雨水高，因本研究研究地點位於茶園中，農田施用的動物糞肥和尿素溢散到空氣中，使得氨的濃度變高，溶於霧水中的氨能有效地提高霧水的pH值。降雨中Na+和Cl-高濃度與高沉降量主要與颱風有關，Ca2+在十二月至三月高濃度主要與相對乾季，沙塵情形相對嚴重有關，NH4+離子濃度較溪頭低可能與農業施肥面積較少有關，NO3-高濃度與高通量主要在四至六月，可能與中國汙染物質遠距傳播有關，SO42-濃度較福山低，可能與東北季風對汙染物質的遠距傳播有關，也可能是因為研究年份相差20年，台灣的酸沉降20年來已有顯著改善所致。霧水攔截物質能力較雨水高，故霧水之離子濃度都較雨水高，但因儀器關係，濃度被稀釋，所以相較其他研究低，霧水離子貢獻量也相對較低，僅NH4+貢獻量相當於雨水71%，高於溪頭的57%，雖然本研究中農家並無過量施肥，但貢獻量已相當高，過量施肥地區貢獻量可能更加可觀，甚至會對周邊生態系造成影響。Acid deposition is a growing environmental problem in the world, with many impacts on ecology. Such as nutrient depletion, forest degradation, acidification of soil and surface water, death of lakes and swamps, and damage to crops. The application of urea and animal manure in agriculture leads to the accumulation of ammonia in the atmosphere. Long-term accumulation may cause an increase in nitrogen deposition that adversely affects soil and plants. This study directly collects the wet deposition in the farmland of Shi-ding and analyzes its chemistry and roughly estimates its flux. The results show that the rainfall pH is less than 5.0, accounting for 53% of all data. Fog water pH below 5.0 only accounts for 28% of all data. The average pH is also higher than rain pH. The research site is located in the tea garden.Animal manure and urea applied to farmland spilled into the air, making the ammonia concentration higher.Ammonia dissolved in mist water can effectively increase the pH value of fog water. The high concentrations of Na+ and Cl- in precipitation are mainly related to typhoons.The high concentration of Ca2+ in December to March is mainly related to the relatively dry season and the relatively serious sand and dust situation. The lower NH4+ ion concentration than that of Xitou may be related to the less agricultural fertilization area.The high concentration of NO3- and high flux are mainly from April to June. May be related to the long-range transmission of Chinese pollutants. The concentration of SO42- is lower than that of Fushan, which may be related to the long-distance transmission of pollutants by the northeast monsoon, or it may be because the research year is 20 years apart.Acid deposition in Taiwan has improved significantly over the past 20 years. The ability of fog water to intercept matter is higher than rainwater, so the ion concentration of fog water is higher than rain water. However, the concentration is diluted due to the instrument, so it is lower than in other studies.The fog water ion flux is also relatively low.Only NH4+ flux is equivalent to 71% of rainwater, which is higher than 57% of Xitou. Although the farmhouse did not over-fertilize in this study, the flux has been quite high.Flux in areas with excessive fertilization maybe even more appreciable and may even affect surrounding ecosystems.