Wagner Ralf, Wagner Elmar
Department of Isotope Hydrology, UFZ Centre for Environmental Research Leipzig-Halle GmbH, Theodor-Lieser-Str. 4, 06120 Halle, Germany.
Isotopes Environ Health Stud. 2006 Dec;42(4):351-65. doi: 10.1080/10256010600991078.
Oxygen and carbon isotopic compositions of tree ring cellulose (delta13Ccell and delta18Ocell) were measured for pines growing at four sites in east Germany. Three sites differed markedly in soil water availability within a short distance and the fourth site served as a reference. The choice of the sites was guided by the desire to detect effects of air pollution on the long-term trend of isotopic compositions and to examine the influence of soil water availability on the relationship between the carbon and oxygen isotope ratios. Locations in east Germany are particularly well suited for the study of pollution effects because there was a steady increase in environmental contamination until the German Reunification in 1990, followed by a sharp decline due to the implementation of stricter environmental standards. The long-term trend of delta13Ccell showed an extraordinary increase in the period 1945-1990 and a rapid decrease after 1990, whereas delta18Ocell remained nearly constant. The increase of delta13Ccell is explained by secondary fractionation caused by phytotoxicity of SO2. Two effects are mainly responsible for the secondary fractionation under SO2 exposure: increase of dark respiration, and changes in photosynthate allocation and partitioning. Both effects do not influence delta18Ocell. Furthermore, a significant positive correlation between the year-to-year variations of carbon and oxygen isotope ratios (delta13Cresid and delta18Oresid) has been found for all sites. The slopes of the relationship between delta13Cresid and delta18Oresid differ insignificantly. It is concluded that this relationship is not influenced by soil water availability but by climatic variables.
对生长在德国东部四个地点的松树的年轮纤维素的氧和碳同位素组成（δ¹³Ccell和δ¹⁸Ocell）进行了测量。其中三个地点在短距离内土壤水分有效性差异显著，第四个地点作为参照。选择这些地点的目的是检测空气污染对同位素组成长期趋势的影响，并研究土壤水分有效性对碳氧同位素比率之间关系的影响。德国东部的地点特别适合研究污染影响，因为在1990年德国统一之前环境污染持续增加，之后由于实施更严格的环境标准而急剧下降。δ¹³Ccell的长期趋势显示在1945 - 1990年期间异常增加，1990年之后迅速下降，而δ¹⁸Ocell几乎保持不变。δ¹³Ccell的增加是由SO₂的植物毒性引起的次生分馏所解释的。在SO₂暴露下，两种效应主要导致次生分馏：暗呼吸增加以及光合产物分配和分区的变化。这两种效应均不影响δ¹⁸Ocell。此外，在所有地点都发现碳和氧同位素比率（δ¹³Cresid和δ¹⁸Oresid）的逐年变化之间存在显著的正相关。δ¹³Cresid和δ¹⁸Oresid之间关系的斜率差异不显著。得出的结论是，这种关系不受土壤水分有效性的影响，而是受气候变量的影响。
