Earthworm secreted calcite granules - constructing a new terrestrial palaeo-environment thermometer and quantifying carbon sequestration potential

蚯蚓分泌的方解石颗粒——构建新的陆地古环境温度计并量化碳封存潜力

基本信息

批准号：
NE/H021914/2
负责人：
Mark Hodson
金额：
$ 19.33万
依托单位：
University of York
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2012
资助国家：
英国
起止时间：
2012 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH021914%2F2
关键词：
Earthworm secreted calcite granules constructing

项目摘要

This proposal seeks to determine the variation of C and O isotope compositions in earthworm secreted calcite granules under different temperatures and concentration of carbon dioxide. We will investigate whether systematic isotopic variation occurs that can be used to interpret terrestrial temperature & carbon dioxide levels during granule formation, and apply our data to granules from a range of archaeological sites: Silbury (4130-4395 BP), Boxgrove (Mid Pleistocene), Laacher See (12900 BP), Odiham Castle (1207-1216 AD) and Ventnor (11690 BP). We will produce a unique environmental interpretation tool that Geoarchaeologists can use to interpret environmental conditions during periods of past human activity. This is because granules are excreted on a daily basis and by analysing a range of granules this will give us the daily temperature ranges experienced during the dated profile/sequence. This has enormous potential for understanding past high resolution climate sequences Earthworms secrete granules of calcite. Our NERC funded investigations to date suggest that Lumbricus terrestris earthworms produce granules of up to 2 mm diameter at an average rate of 0.8 mg of CaCO3 per earthworm per day. Our dissolution experiments indicated that earthworm secreted calcite dissolves at the same rate as inorganically produced calcite and modelling suggests that calcite grains the same size as our granules can survive for 1000 - 10000 years in soils of bulk pH as low as 5.4. In addition granules have been recovered from Silbury and Boxgove sediments. Those from Silbury have been dated using 14C as 4130 - 4395 years BP and 4670 years BP by ourselves using U-series dating Clearly earthworm secreted calcite granules can survive for significant periods of time in soils. This raises the exciting possibility, supported by our preliminary work, of dating individual granules and measuring their C & O isotopes to interpret the environmental conditions during their formation. Individual granules contain sufficiently high concentrations of U and low concentrations of Th that U-series dating can be applied. They have C and O isotopic signatures indicative of derivation from a mixture of soil organic matter, atmospheric gases and soil water. As they contain a component of atmospheric oxygen their isotopic signature should fluctuate with temperature We will investigate isotope dynamics of the granules in several ways 1. We will culture L. terrestris in three different soils at different temperatures and carbon dioxide concentrations in a factorial arrangement - all possible combinations of temperature and carbon dioxide concentration will be investigated. We will sample granules after 30, 60, 90 and 120 days to confirm that isotopic steady state has been achieved. We anticipate that this will be the case on the basis of previous studies investigating C incorporation into granules. Differences in the isotopic compositions of the various components of our system and granules will be plotted against temperature to determine a relationship between isotopic composition and temperature 2. We will confirm the relative proportions of atmospheric, aqueous and organic matter C and O present in the granules by culturing L. terrestris in the same 3 soils. We will conduct the experiments at ambient carbon dioxide conditions with known moisture contents of different isotopic compositions. To keep costs down we will use Middle Eastern and American mineral waters. Again we will sample granules after 30, 60, 90 and 120 days. We will determine the relative proportions of our different C and O sources in our granules using mixing diagrams 3. Lastly we will perform U/Th dating and C and O analyses on granules donated by our project partners (English Heritage, Boxgrove) and interpret environmental conditions during granule formation using the relationships derived in our previous experiments. This will help interpret these important archaeological sites.

该提案旨在确定不同温度和二氧化碳浓度下蚯蚓分泌的方解石颗粒中C和O同位素组成的变化。我们将研究是否发生系统性同位素变化，这些变化可用于解释颗粒形成过程中的陆地温度和二氧化碳水平，并将我们的数据应用于来自一系列考古遗址的颗粒：锡尔伯里（4130-4395 BP）、博克斯格罗夫（中更新世）、拉彻湖（Laacher See，距今 12900 年）、奥迪厄姆城堡（Odiham Castle，公元 1207-1216 年）和文特诺城堡（Ventnor，公元 11690 年）英国石油公司）。我们将开发一种独特的环境解释工具，地质考古学家可以用它来解释过去人类活动期间的环境条件。这是因为颗粒每天都会排出，通过分析一系列颗粒，这将为我们提供在日期曲线/序列期间经历的每日温度范围。这对于了解过去的高分辨率气候序列具有巨大的潜力。蚯蚓分泌方解石颗粒。迄今为止，我们 NERC 资助的调查表明，Lumbricus terrestris 蚯蚓会产生直径达 2 毫米的颗粒，平均每只蚯蚓每天产生 0.8 毫克 CaCO3。我们的溶解实验表明，蚯蚓分泌的方解石的溶解速度与无机产生的方解石相同，并且模型表明，与我们的颗粒大小相同的方解石颗粒可以在本体 pH 值低至 5.4 的土壤中存活 1000 - 10000 年。此外，还从锡尔伯里和博克斯戈夫沉积物中回收了颗粒。来自锡尔伯里的那些已使用 14C 测年为距今 4130 - 4395 年，我们自己使用 U 系列测年法测年为距今 4670 年。显然，蚯蚓分泌的方解石颗粒可以在土壤中存活很长一段时间。在我们的前期工作的支持下，这提出了令人兴奋的可能性，即对单个颗粒进行年代测定并测量其 C 和 O 同位素，以解释其形成过程中的环境条件。单个颗粒含有足够高浓度的 U 和低浓度的 Th，可以应用 U 系列测年。它们具有 C 和 O 同位素特征，表明源自土壤有机质、大气气体和土壤水的混合物。由于它们含有大气氧的成分，因此它们的同位素特征应随温度波动。我们将通过多种方式研究颗粒的同位素动力学 1. 我们将在三种不同的土壤中在不同的温度和二氧化碳浓度下以因子排列培养 L. terrestris -将研究温度和二氧化碳浓度的所有可能组合。我们将在 30、60、90 和 120 天后对颗粒进行取样，以确认已达到同位素稳态。根据之前调查碳掺入颗粒的研究，我们预计情况会如此。我们的系统和颗粒的各个组成部分的同位素组成差异将根据温度绘制，以确定同位素组成和温度之间的关系 2。我们将确认颗粒中存在的大气、水和有机物质 C 和 O 的相对比例通过在相同的 3 种土壤中培养 L. terrestris。我们将在已知的不同同位素组成的水分含量的环境二氧化碳条件下进行实验。为了降低成本，我们将使用中东和美国的矿泉水。我们将在 30、60、90 和 120 天后再次对颗粒进行取样。我们将使用混合图 3 确定颗粒中不同 C 和 O 来源的相对比例。最后，我们将对项目合作伙伴（English Heritage、Boxgrove）捐赠的颗粒进行 U/Th 测年以及 C 和 O 分析，并解释环境使用我们之前实验中得出的关系来确定颗粒形成过程中的条件。这将有助于解释这些重要的考古遗址。

项目成果

期刊论文数量（4）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Biomineralisation by earthworms - an investigation into the stability and distribution of amorphous calcium carbonate.

DOI：
10.1186/s12932-015-0019-z
发表时间：
2015
期刊：
Geochemical transactions
影响因子：
2.3
作者：
Hodson ME;Benning LG;Demarchi B;Penkman KE;Rodriguez-Blanco JD;Schofield PF;Versteegh EA
通讯作者：
Versteegh EA

Carbon isotope fractionation between amorphous calcium carbonate and calcite in earthworm-produced calcium carbonate

蚯蚓产生的碳酸钙中无定形碳酸钙和方解石的碳同位素分馏