Mass balance models for use with 210Pbex measurements to estimate soil loss from cultivated land
Mass balance models for use with 210Pbex measurements to estimate soil loss from cultivated land
复制标题
与 210Pbex 测量一起使用的质量平衡模型来估算耕地的土壤流失
DOI：
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
中科院分区：
文献类型：
--
作者：
210Ph(半衰期22.3年)是238U衰变系列的自然产物，238U衰变系由气态222Rn(半衰期3.8天)衰变而来，22Ra(半衰期1622年)的子体。与大气降尘137Cs一样，作为大气降尘到达地表的210Pbex将迅速被表层土壤吸收，随后在景观中的重新分布将反映与土壤侵蚀和泥沙输送过程相关的土壤和沉积物颗粒的运动。因此，放射性核素具有相当大的潜力，可用作估计土壤侵蚀率的示踪剂。它可用于131Cs库存较低的地区，因此难以测量，或因额外的化学试剂输入而变得复杂的地区。此外，由于它基本上是随着时间的推移而不变的输入，它可以提供更长时间内侵蚀速率的信息。利用质量平衡方法建立了转换模型，用于从210PbEX测量数据推算耕地土壤再分配率。然而，有必要改进这些模型，以考虑210PbEX在土壤剖面中重新分布的关键特征。在大多数耕作土壤中，210Pbex均匀分布在耕层内，但210Pbex中有一小部分通常分布在耕层以下，形成了向深度分布的尾巴。这条尾巴反映了210PbEX向下移动到耕层以下土壤中的一系列机制，这些机制可以表示为扩散和迁移过程。现有的转换模型忽略了210Pbex在耕作土壤中深度分布的这一特征，从而高估了土壤流失率。本文报道了考虑水深分布尾部的质量平衡修正模型的发展。用修正模型估算的土壤流失量大于现有模型估算的土壤流失量，其大小取决于土壤性质，如犁深(H)、犁底层的210Pbex深度分布系数(H0)和犁底层与耕层的土壤容重比(γpp/γp)。
210Pb (half-life 22.3 years) is a natural product of the 238 U decay series that is derived from the decay of gaseous 222 Rn (half-life 3.8 days), the daughter of 226 Ra (half-life 1622 years). Like fallout 137 Cs, 210 Pb ex reaching the land surface as fallout from the atmosphere will be rapidly adsorbed by the surface soil and its subsequent redistribution within the landscape will reflect the movement of soil and sediment particles associated with soil erosion and sediment transport processes. The radionuclide therefore offers considerable potential for use as a tracer for estimating soil erosion rates. It can be used in regions where 131 Cs inventories are low, and therefore difficult to measure, or where they are complicated by additional Chemobyl inputs. Furthermore, due to its essentially constant input over time, it can provide information on erosion rates over a longer period of time. Conversion models utilizing a mass balance approach have been developed for deriving estimates of soil redistribution rates on cultivated land from 210 Pb ex measurements. There is, however, a need to refine these models to take account of key features of the redistribution of 210 Pb ex in the soil profile. In most cultivated soils 210 Pb ex is evenly distributed within the plough layer, but a small proportion of the 210 Pb ex inventory is commonly found below the plough layer, forming a tail to the depth distribution. This tail reflects the downward movement of 210 Pb ex into the soil below the plough layer by a range of mechanisms that can be represented as diffusion and migration processes. Existing conversion models ignore this feature of the depth distribution of 210 Pb ex in cultivated soils and therefore overestimate rates of soil loss. This paper reports the development of a revised mass balance model that takes account of the tail of the depth distribution. Soil losses estimated by using the revised model are greater than those estimated by the existing models and the extent is determined by the soil properties, which are related to transportation of the 210 Pb ex nuclide from the plough layer to the plough pan layer, such as the plough depth (H), the 210 Pb ex depth distribution coefficient (h 0 ) in the plough pan layer and the ratio of soil bulk densities between the plough pan layer and plough layer (γ pp /γ p ).
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影响因子：
2.2
作者：
A. Nevissi
通讯作者：
A. Nevissi
影响因子：
5.7
作者：
Jin-Jun Zheng;Xiu-bin He;D. Walling;Xin-bao Zhang;D. Flanagan;Y. Qi
通讯作者：
Jin-Jun Zheng;Xiu-bin He;D. Walling;Xin-bao Zhang;D. Flanagan;Y. Qi
DOI：
10.1007/0-306-48054-9
发表时间：
2003
期刊：
--
影响因子：
--
作者：
F. Zapata
通讯作者：
F. Zapata
DOI：
10.2136/sssaj1996.03615995006000040035x
发表时间：
1996-07
影响因子：
2.9
作者：
P. Wallbrink;A. Murray
通讯作者：
P. Wallbrink;A. Murray
影响因子：
3.9
作者：
D. Walling;A. Collins;H. Sichingabula
通讯作者：
D. Walling;A. Collins;H. Sichingabula