The Global Distribution of Acidifying Wet Deposition
详细信息 查看全文
- 作者：Henning Rodhe ; Frank Dentener ; and Michael Schulz
- 刊名：Environmental Science & Technology
- 出版年：2002
- 出版时间：October 15, 2002
- 年：2002
- 卷：36
- 期：20
- 页码：4382 - 4388
- 全文大小：1530K
- 年卷期：v.36,no.20(October 15, 2002)
- ISSN：1520-5851
文摘
The acid-base status of precipitation is a result of abalance between acidifying compounds-mainly oxides ofsulfur and nitrogen-and alkaline compounds-mainlyammonia and alkaline material in windblown soil dust. Weuse current models of the global atmospheric distributionof such compounds to estimate the geographicaldistribution of pH in precipitation and of the rate ofdeposition of hydrogen ion or bicarbonate ion. The lowestpH values-mainly due to high concentration of sulfuricacid-occur in eastern parts of North America, Europe, andChina. A comparison with observed pH values showsfair agreement in most parts of the world. However, insome areas, e.g. western North America, southwesternEurope, and northern China the estimated pH is too low,indicating that we have underestimated the deposition fluxof alkaline material, probably mainly CaCO3. Our neglectof organic acids may have contributed to an overestimateof pH especially in certain tropical areas. To illustratethe potential effects of acidifying deposition on nitrogensaturated terrestrial ecosystems we also calculate thedeposition of "potential acidity" that takes into account themicrobial transformation of ammonium to nitrate in suchecosystems, resulting in the release of hydrogen ion.Compared to the deposition of acidity, with its maximaover Europe, eastern North America, and southern China,the deposition of potential acidity exhibits an additionalmaximum in India and Bangladesh and in several othersmaller hot spots where the cycling of ammonia is enhancedby a dense cattle population. To the extent that soils inthese areas of high potential acidity deposition actuallybecome nitrogen saturated a depletion of base cations andother changes in soil chemistry and biology should beexpected. Potential problem areas for future soil acidificationinclude several regions with sensitive soils in southern,southeastern, and eastern Asia as well as in central partsof South America.