The geographic distribution of strontium isotopes in Danish surface waters - A base for provenance studies in archaeology, hydrology and agriculture
The geographic distribution of strontium isotopes in Danish surface waters - A base for provenance studies in archaeology, hydrology and agriculture
复制标题
DOI：
10.1016/j.apgeochem.2010.12.006
复制
发表时间：
2011-03-01
影响因子：
3.4
通讯作者：
Frei, Robert
中科院分区：
文献类型：
--
作者：
Frei, Karin M.;Frei, Robert
本文报道了192个地表水的Sr同位素特征（湖泊/池塘和河流/小溪）样本从丹麦和同位素分布图，可作为一个基础的起源应用，包括考古迁移研究，地下水-地表水-海水相互作用/污染监测，并可能为农业应用，包括特定食品的真实性证明的情况。表层沃茨的Sr同位素组成范围为Sr-87/Sr-86 = 0.7078 ~ 0.7125（平均值为0.7096 ± 0.0016; 2 σ）。该平均值高于晚白垩世至早第三纪（渐新世）石灰岩预期的Sr-87/Sr-86值范围（0.7078至0.7082），这些石灰岩形成丹麦西北-东南向带的主要基岩类型。升高的87 Sr/86 Sr信号>类似于0.7095，这是由于放射性Sr主要来自近地表风化和第四纪冰川形成的冰碛物和土壤的冲刷，在最后两个冰河期阶段（Saale和Weichsel）期间和之后沉积和形成，从而增加了地表沃茨。锶同位素组成和浓度的表面沃茨，因此，最好是由一个两个组件的混合涉及碳质基岩和冰川覆盖沉积物作为两个主要的锶源建模。在没有使用和应用商业肥料的西兰岛（传奇之地，莱日尔）的一个代表性试验区进行了一项可行性研究，使用地表沃茨的Sr同位素组成作为生物可利用Sr特征的替代物。结果表明，本区沃茨的Sr同位素特征略高（但在统计上仍然无法区分）与蜗牛壳和土壤浸出液定义的平均值被认为是真正的生物有效Sr的特征。结合其他研究的结果，这被解释为反映了表层土壤风化释放到饱和地下水位中的具有较高87 Sr/86 Sr特征的Sr的冲刷，因此，这种成分不容易转移到浅根植物和以它们为食的小型食草动物中。由于饮用水是一个可能的重要来源的锶摄取的人类和大型动物，争论的是，地表水的同位素组成可以潜在的特征的生物可利用的组件相关的人类和肉食性大型动物。样条函数和普通线性克里格法被用来模拟生物有效锶同位素的地理分布超过领土丹麦。正如预期的那样，基于两源混合情景，水Sr-87/Sr-86比值等值线图（除了一些明显的例外）既不反映前第四纪基岩地质，（更新世）丹麦土壤类型分布图。作为一个保守的建议，推荐使用平均Sr-87/Sr-86比值0.7096 +/- 0.0015（2 σ）作为丹麦内生物可利用Sr的平均值（不包括Brnholm）用于人类和大型动物，并作为在考古学来源研究中区分“cal”和“非本地”特征的置信带。土壤提取物和小型食草动物的Sr-87/Sr-86比值约为0.7088，比地表沃茨的Sr-87/Sr-86比值低0.15%。作者建议使用这个较低的值作为农业应用中食品和植物真实性控制的“本地”-“非本地”标记。(C)2010爱思唯尔有限公司版权所有。
In this paper Sr isotope signatures are reported for 192 surface water (lakes/ponds and rivers/creeks) samples from within Denmark and an isotope distribution map is presented that may serve as a base for provenance applications, including archaeological migration studies, ground water - surface water - seawater interaction/contamination monitoring, and potentially for agricultural applications, including cases of authenticity proof for particular food products. The Sr isotopic compositions of surface waters range from Sr-87/Sr-86 = 0.7078 to 0.7125 (average 0.7096 +/- 0.0016; 2 sigma). This average value lies above the range of Sr-87/Sr-86 values between 0.7078 and 0.7082 expected from Late Cretaceous to Early Tertiary (Oligocene) limestones which form the dominant bedrock type in a NW-SE trending belt in Denmark. The elevated 87Sr/86Sr signatures >similar to 0.7095 are explained by additions to the surface waters of radiogenic Sr predominantly derived from the near-surface weathering and wash-out of Quarternary glaciogenic tills and soils deposited and formed during and after the last two ice age stages (Saale and Weichsel). The Sr isotopic compositions and concentrations of the surface waters can, therefore, best be modeled by a two-component mixing involving carbonaceous bedrock and glaciogenic cover sediments as the two predominant Sr sources. A feasibility study for using Sr isotopic compositions of surface waters as a proxy for bio-available Sr signatures was conducted in a representative test area on Zealand (Land of Legends, Lejre) where there is no use and application of commercial fertilizers. It is demonstrated that the Sr isotopic signatures of lake waters from within this area are slightly higher (but statistically still indistinguishable) from the average value defined by snail shells and soil leachates considered to characterize the true bio-available Sr. In combination with results from other studies, this is interpreted to reflect the wash-out of Sr with a higher 87Sr/86Sr signature released by weathering in the topsoils into the saturated water tables, a component which is consequently not readily transferred into the shallow-rooting plants and into small herbivores feeding on them. Since drinking water is a likely important source of Sr uptake of humans and larger animals, the contention is that a surface water isotopic composition can potentially characterize the bio-available component relevant for human and carnivorous large animals. Spline functions and ordinary linear kriging were used for modeling the geographic distribution of bio-available Sr isotopes over territorial Denmark. As expected, based on the two-source mixing scenario, the water Sr-87/Sr-86 ratio contour maps (with some notable exceptions) neither mirror the pre-Quarternary bedrock geology nor a (Pleistocene) soil-type distribution map of Denmark.As a conservative suggestion, the use of the average Sr-87/Sr-86 ratio of 0.7096 +/- 0.0015 (2 sigma) is recommended as an average for bio-available Sr from within Denmark (brnholm excluded) for human and larger animals and as a confidence band for distinguishing cal" from "non-local" signatures in archaeological provenance studies. The study also reveals th the average Sr-87/Sr-86 ratio of similar to 0.7088 defined from soil extracts and small herbivores lies approximately 0.15% lower than that defined by the surface waters. The authors recommend using this lower value as a "local"-"non-local" discriminator for food and plant authenticity control in agricultural applications. (C) 2010 Elsevier Ltd. All rights reserved.