A stable lead isotopic investigation of the use of sycamore tree rings as a historical biomonitor of environmental lead contamination.
A stable lead isotopic investigation of the use of sycamore tree rings as a historical biomonitor of environmental lead contamination.
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DOI：
10.1016/j.scitotenv.2005.12.004
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发表时间：
2006-06
期刊：
影响因子：
--
通讯作者：
G. J. Patrick;J. G. Farmer
中科院分区：
文献类型：
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作者：
G. J. Patrick;J. G. Farmer
研究了利用梧桐树年轮重建大气铅污染历史的有效性。 1892 年至 2003 年的树芯是从苏格兰洛蒙德湖东岸的几棵梧桐树上收集的，该地区没有当地铅排放点源。将洛蒙德湖地区岩心的铅浓度和 206 Pb/207 Pb 剖面与 210 Pb 测年的湖泊沉积物的相应数据以及来自苏格兰植物标本馆收藏的已知年龄的苔藓数据进行了比较。七个梧桐岩芯中的两个显示出与流入湖泊的铅通量相同的铅浓度趋势，其余的彼此或与湖泊沉积物记录没有相似之处。另外两个梧桐岩心在其时间 206 Pb/207 Pb 趋势方面与沉积物和苔藓记录中所见的趋势有些相似，但仅在其剖面的部分部分相似，而其他梧桐岩心的 206 Pb/207 Pb 比率在覆盖的大部分时间内保持相对不变，或表现出相反的趋势。树芯的 206Pb/207Pb 比率也大多高于任何给定时间段内先前建立的记录。还沿着 Wanlockhead 和 Tyndrum 的横断面收集了覆盖 1878 年至 2002 年的树芯，这两个地区以前是铅开采和冶炼区，206Pb/207Pb 的比率分别为 1.170 和 1.144。 Wanlockhead 树芯的铅浓度随着时间和距铅矿的距离而总体呈下降趋势。在靠近矿井的样品中观察到 206Pb/207Pb 的特征比为 1.170，但在较远的样品中观察到来自矿井的铅的影响有所下降。在 Tyndrum 采样的树木显示出铅浓度升高，并随着时间的推移而降低，并且 206Pb/207Pb 比率相当恒定，约为 1.15，反映了来自矿井的输入，这是沿横断面的任何其他树木中未观察到的特征。总体而言，数据表明，梧桐树年轮分析不适合在当地没有大量铅输入的地区获取历史铅沉积记录，尽管它可以揭示有关点源排放源的时间和空间影响的一些信息。不适合的原因可能是一年中活跃年轮的数量、元素吸收后的径向易位、不同吸收途径的相对重要性以及树木吸收养分的土壤深度。
The validity of the use of sycamore (Acer pseudoplatanus) tree-rings for the reconstruction of atmospheric lead pollution histories was investigated. Tree cores spanning 1892–2003 were collected from several sycamores from the eastern shore of Loch Lomond, Scotland, an area with no local point sources of lead emission. The lead concentration and206Pb/207Pb profiles of the Loch Lomond region cores were compared with corresponding data for the210Pb-dated loch sediment, and also with data for moss of known age from a Scottish herbarium collection. Two of the seven sycamore cores showed the same lead concentration trend as the lead flux to the loch, the rest having no similarity to either each other or the loch sediment record. Two further sycamore cores showed some similarity in their temporal206Pb/207Pb trends to those seen in the sediment and moss records, but only in part of their profiles, whilst the206Pb/207Pb ratios of the other sycamore cores remained relatively unchanged for the majority of the time covered, or exhibited an opposite trend. The206Pb/207Pb ratios of the tree cores were also mostly higher than those of the previously established records for any given time period. Tree cores covering 1878–2002 were also collected along transects from Wanlockhead and Tyndrum, two areas of former lead mining and smelting associated with distinct206Pb/207Pb ratios of 1.170 and 1.144, respectively. The Wanlockhead tree cores exhibited a generally decreasing trend in lead concentration with both time and distance from the lead mine. The characteristic206Pb/207Pb ratio of 1.170 was observed in samples close to the mine but a decrease in the influence of the mine-derived lead was observed in more distant samples. The tree sampled at Tyndrum showed elevated lead concentrations, which decreased with time, and a fairly constant206Pb/207Pb ratio of ∼1.15 reflecting input from the mine, features not observed in any other trees along the transect. Overall the data suggest that sycamore tree-ring analysis is an unsuitable method for obtaining records of historical lead deposition in areas with no large local lead input, although it can reveal some information about the temporal and spatial influence of point source emitters. The unsuitability probably arises from the number of active annual rings in a single year, the post-uptake radial translocation of elements, the relative importance of the different routes of uptake, and the soil depth(s) from which trees draw nutrients.