Toward a general evaluation model for soil respiration (GEMSR)

Soil respiration is an important component of terrestrial carbon budget. Its accurate evaluation is es- sential to the study of terrestrial carbon source/sink. Studies on soil respiration at present mostly focus on the temporal variations and the controlling factors of soil respiration, but its spatial variations and controlling factors draw less attention. Moreover, the evaluation models for soil respiration at present include only the effects of water and heat factors, while the biological and soil factors controlling soil respiration and their interactions with water and heat factors have not been considered yet. These models are not able to accurately evaluate soil respiration in different vegetation/terrestrial ecosystems at different temporal and spatial scales. Thus, a general evaluation model for soil respiration (GEMSR) including the interacting meteorological (water and heat factors), soil nutrient and biological factors is suggested in this paper, and the basic procedure developing GEMSR and the research tasks of soil respiration in the future are also discussed.

浙江省典型水稻产区土壤-水稻系统重金属迁移特征及定量模型

重金属在土壤·水稻系统中迁移转化规律越来越受到人们的关注。本研究采集浙江省3个不同区位（浙北南浔、浙中嵊州、浙南温岭）的水稻主产区土壤、水稻样品,基于水稻品种（杂交水稻和晚粳稻）进行重金属迁移转化的影响因子分析,明确主要驱动因子,建立定量评测模型并进行验证,以此掌握浙江省典型水稻产区重金属的迁移转化规律。研究结果表明,3个研究区土壤的理化性状存在差异,其中嵊州产区土壤的p H（均值为5.52）、有机质（均值为39.4 g·kg·1）、重金属形态含量等均低于其他两个研究区;3个产区土壤和水稻中重金属含量也存在显著性差异,温岭产区土壤重金属（Cd、Cu、Zn）含量显著高于其他两个产区（P〈0.05）,而嵊州产区的水稻重金属含量则显著高于南浔产区（P〈0.05）;Cd和Zn富集系数高于Cu和Ni,嵊州产区的重金属富集系数（0.018~0.521）显著高于其他两个产区（南浔为0.004~0.143,温岭为0.007~0.269）。土壤重金属形态和土壤理化性质均显著影响不同品种的富集系数,其中土壤理化性质的作用相对较大。对数线性迁移模型能够预测实际产地环境中土壤·水稻系统重金属的有效性（富集系数）,晚粳稻的预测结果优于杂交水稻,重金属Ni的预测效果（杂交水稻和晚粳稻的回归系数r分别达0.61、0.70,P〈0.01）好于其他重金属,而杂交水稻重金属Cd的预测效果（r值为0.21,P〉0.05）偏低,需增加环境变量,并做进一步研究以提高预测精度。