Botany and Microbiology Department, Faculty of Science, Helwan University, Cairo, Egypt; Regional Climate Group, Department of Earth Sciences, University of Gothenburg, Gothenburg, Sweden.
Regional Climate Group, Department of Earth Sciences, University of Gothenburg, Gothenburg, Sweden.
Sci Total Environ. 2015 Apr 15;512-513:1-7. doi: 10.1016/j.scitotenv.2015.01.032. Epub 2015 Jan 19.
Wastewater reuse for agriculture is an important management strategy in areas with limited freshwater resources, yielding potential economic and environmental benefits. Here the effects of long-term irrigation with wastewater on the nutrient contents of green and senesced leaves of Cupressus sempervirens L. were assessed for three planted forests in Egypt. Stoichiometric ratios, transfer factors for nutrients from soil to plant and enrichment factors in contaminated soils were estimated and compared to a ground water irrigated control site. Under wastewater irrigation, C. sempervirens transferred most of the estimated nutrients, particularly heavy metals, from green to senesced leaves. This could be a self-protecting mechanism under continuous wastewater irrigation. The accumulation of four metals (Zn, Mn, Cu and Cd) with transfer factors>1 for wastewater-irrigated trees, indicated the ability for metal accumulation of C. sempervirens. Stoichiometric ratios decreased under wastewater irrigation compared to the control site and global trends, which suggests nutrient disorders in these plants. The values of enrichment factors in the wastewater-irrigated soils showed remarkable availability and distribution of metals. Decreased resorption of metals by senesced leaves of C. sempervirens will add considerable amount of these metals to the soils, which will likely have adverse affects on the desert ecosystem components.
污水回用农业是在淡水资源有限的地区的重要管理策略，产生潜在的经济和环境效益。在这里，评估了长期灌溉废水对埃及三个种植林的柏木绿色和衰老叶片的养分含量的影响。估计了化学计量比、从土壤到植物的养分转移因子和受污染土壤的富集因子，并与地下水灌溉的对照点进行了比较。在污水灌溉下，柏木将大部分估计的养分，特别是重金属，从绿色转移到衰老的叶片。这可能是在连续污水灌溉下的自我保护机制。四个金属（Zn、Mn、Cu 和 Cd）的转移因子>1，表明柏木具有金属积累能力。与对照点和全球趋势相比，污水灌溉下的化学计量比下降，这表明这些植物存在营养障碍。污水灌溉土壤中的富集因子值表明金属具有很高的有效性和分布性。衰老的柏木叶片对金属的再吸收减少，将大量这些金属添加到土壤中，这可能对沙漠生态系统的组成部分产生不利影响。
