摘要
一直以来,研究者发现在中国南方及东南亚地区存在土壤酸化超出标准稳定状态的临界载荷的现象,但尚无证据能够说明土壤酸化在中国境外的影响。本研究介绍了一种在硫(S)、氮(N)和钙(Ca)的未来潜在排放情景下,亚洲土壤敏感性对酸沉降的时间效应的计算方法。这种方法通过对亚洲可用性数据的匹配,制作了区域尺度图,估算了在相应的酸沉降条件下,土壤盐基饱和度需要多少时间(年)能达到20%的临界上限。研究结果表明,南亚、东南亚和东亚的土壤类型敏感地区,包括中国南部部分地区,以及缅甸、海南、老挝、泰国、越南和印度西高止山脉等,达到显著酸化的程度可能需要0～50年(尺度),这主要取决于当地的管理水平、生物和非生物的因素等。为了更明确地评估风险,需要贯穿亚洲代表不同植被和土壤类型及管理制度的典型区域的定点观测数据,如土壤化学、沉降(尤其是相应的阳离子沉降)、土壤和生态系统中硫、氮含量、可收获的生物量及风化速率等。本文介绍的国家和区域评估土壤的简单方法,可以对土壤酸化相关的影响时间尺度进行正确评价,有助于下一步研究,通过相关措施可降低酸化的风险。
Exceedance of steady-state critical loads for soil acidification is consistently found in southern China and parts of SE Asia,but there is no evidence of impacts outside of China.This study describes a methodology for calculating the time to effects for soils sensitive to acidic deposition in Asia under potential future sulfur (S),nitrogen (N),and calcium (Ca) emission scenarios.The calculations are matched to data availability in Asia to produce regional-scale maps that provide estimates of the time (y) it will take for soil base saturation to reach a critical limit of 20% in response to acidic inputs.The results show that sensitive soil types in areas of South,Southeast,and East Asia,including parts of southern China,Burma,Hainan,Laos,Thailand,Vietnam,and the Western Ghats of India,may acidify to a significant degree on a 0-50 y timescale,depending on individual site management and abiotic and biotic characteristics.To make a clearer assessment of risk,site-specific data are required for soil chemistry and deposition (especially base cation deposition); S and N retention in soils and ecosystems;and biomass harvesting and weathering rates from sites across Asia representative of different soil and vegetation types and management regimes.National and regional assessments of soils using the simple methods described in this paper can provide an appreciation of the time dimension of soil acidification- related impacts and should be useful in planning further studies and,possibly,implementing measures to reduce risks of acidification.
