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

• 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

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.

该建议旨在确定在不同温度和二氧化碳浓度下earth分泌方解石颗粒中C和O同位素组成的变化。 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）。我们将生成一种独特的环境解释工具，地理学家可以在过去的人类活动期间使用该工具来解释环境条件。这是因为颗粒每天被排出，并且通过分析一系列颗粒，这将为我们提供日期剖面/序列中经历的每日温度范围。这具有理解过去高分辨率气候序列earth的巨大潜力，分泌方解石的颗粒。迄今为止，我们的NERC资助的调查表明，lumbricus terrestris earth的颗粒直径高达2 mm，平均每天每天0.8 mg CACO3。我们的溶解实验表明，earth分泌的方解石以与无机产生的方解石相同的速率溶解，并且建模表明，方解石晶粒的大小与我们的颗粒可以在低至5.4的块状pH的土壤中生存1000 - 10000年。另外，从西尔伯里（Silbury）和盒装沉积物中回收了颗粒。席尔伯里（Silbury）的人使用14C AS 4130 - 4395年的BP和4670年的BP使用U系列使用U系列的日期来看，明显的earth earth分泌的方解石颗粒可以在土壤中存活很长时间。这提出了令人兴奋的可能性，并在我们的初步工作，约会单个颗粒和测量其C＆O同位素以解释其形成过程中的环境条件的支持下。单个颗粒含有足够高的U浓度，可以应用U系列约会的低浓度的Th。它们具有C和O同位素特征，指示来自土壤有机物，大气气和土壤水的混合物的衍生。由于它们包含大气氧的组成部分，因此它们的同位素特征应随温度而波动，我们将以几种方式研究颗粒的同位素动力学1。我们将在不同温度和二氧化碳浓度下在三种不同的土壤中培养甲状腺杆菌，并在阶乘安排中进行二氧化碳浓度 - 所有可能的温度和二氧化物浓度的组合。我们将在30、60、90和120天后采样颗粒，以确认已经实现了同位素稳态。我们预计将根据先前研究C纳入颗粒的研究而是这种情况。我们系统和颗粒的各个组件的同位素组成的差异将在温度下绘制，以确定同位素成分和温度2之间的关系。我们将通过在同一3种土壤中培养L. terrestris中存在大气，水性和有机物C和O的相对比例。我们将在具有不同同位素组成的已知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矿物水域。同样，我们将在30、60、90和120天后采样颗粒。我们将使用混合图3来确定颗粒中不同C和O源的相对比例。最后，我们将对我们的项目合作伙伴（英语遗产，Boxgrove）捐赠的颗粒捐赠的U/Th日期和O分析，并使用先前的实验中的关系来解释颗粒形成期间的环境条件。这将有助于解释这些重要的考古遗址。

项目成果

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

• DOI: 10.1016/j.apgeochem.2017.01.017
• 发表时间: 2017
• 期刊: Applied Geochemistry
• 影响因子: 3.4
• 作者: Versteegh E