Environmental controls on the production of calcium carbonate by earthworms

Lumbricus terrestris earthworms produce calcium carbonate (CaCO3) granules with unknown physiological function. To investigate carbon sequestration potential, the influence of temperature and CO2 concentration ([CO2]) on CaCO3 production was investigated using three soils, five temperatures (3-20 C) and four atmospheric [CO2] (439-3793 ppm). Granule production rates differed between soils, but could not be related to any soil characteristics measured. Production rates increased with temperature, probably because of higher metabolic rate, and with soil CO2 concentration. Implications for carbon sequestration are discussed. CaCO3 production in earthworms is probably related to pH regulation of blood and tissue fluid in the high CO2 environment of the soil

Clumped isotope thermometry in earthworm carbonates

Earthworm-secreted calcium carbonate can store carbon derived from the soil-atmosphere interface on geological timescales [1]. The mechanism of calcification [2,3,4] is well understood based on multiple years of research conducted both under controlled and natural conditions. We analysed carbonate granules produced by the earthworm Lumbricus terrestris cultured in variable pH and temperature for δ18O to establish thermometry [2]. The governing equation proposed for the thermometry differed from the inorganic calcite precipitation relationship, capturing the signature of kinetic processes during carbonate growth. We have now analysed the granules for clumped isotope thermometry. This provides an opportunity to understand the role of kinetic processes in governing the relationship of clumped isotope in the carbonate system. The clumped isotopic composition of these carbonates yields the following relationship with varying temperature: The linear regression relationship obtained in this study has a similar slope as seen in case of inorganic calcite [5] and otolith carbonate [6]. However, the intercept of the governing equation varied significantly denoting carbonate growth rate. The study presented here provides the first experimental results of clumped isotope composition on carbonates precipitated under monitored disequilibrium conditions and thus, enables quantification of growth rate dependency on clumping. The intercept of the linear regression relationship differs from the line proposed for inorganic calcite precipitation and thus introduces a new parameter to quantify the kinetic process. In this study replicate experiments were performed on carbonate granules generated at controlled temperature and with a knowledge of water isotopic compositio

Earthworm-produced calcite granules: a new terrestrial palaeothermometer?

In this paper we show for the first time that calcite granules, produced by the earthworm Lumbricus terrestris, and commonly recorded at sites of archaeological interest, accurately reflect temperature and soil water δ18O values. Earthworms were cultivated in an orthogonal combination of two different (granule-free) soils moistened by three types of mineral water and kept at three temperatures (10, 16 and 20 ºC) for an acclimatisation period of three weeks followed by transfer to identical treatments and cultivation for a further four weeks. Earthworm-secreted calcite granules were collected from the second set of soils. δ18O values were determined on individual calcite granules (δ18Oc) and the soil solution (δ18Ow). The δ18Oc values reflect soil solution δ18Ow values and temperature, but are consistently enriched by 1.51 (±0.12) ‰ in comparison to equilibrium in synthetic carbonates. The data fit the equation 1000 ln α = [20.21 ± 0.92] (103 T-1) - [38.58 ± 3.18] (R2 = 0.95; n = 96; p < 0.0005). As the granules are abundant in modern soils, buried soils and archaeological contexts, and can be dated using U-Th disequilibria, the developed palaeotemperature relationship has enormous potential for application to Holocene and Pleistocene time intervals

Comparison of a home-based (multi) systemic intervention to promoting Medication AdheRence and Self-management among kidney transplant recipients with care-as-usual: the MARS randomized controlled trial protocol

BACKGROUND: After kidney transplantation non-adherence and inadequate self-management undermine clinical outcomes and quality of life. Both have been demonstrated to be substantial in all age groups. However, interventions promoting adherence and self-management among kidney transplant recipients that have proven to be effective are scarce. In this study we aim to develop and test an intervention to optimize adherence and self-management. In this article we describe the background and design of the trial entitled 'promoting Medication AdheRence and Self-management among kidney transplant recipients' (MARS-trial)'. METHODS/DESIGN: This is a single-center, parallel arm randomized controlled trial. Nonadherent kidney transplant recipients aged 12 years or older are eligible for inclusion. Patients will be randomly assigned to either the experimental or a control group. The control group will receive care-as-usual. The experimental group will receive care-as-usual plus the MARS-intervention. The MARS-intervention is an outreaching intervention, based on the principles of (multi) systemic therapy which means involving the social network. A standardized intervention protocol is used for consistency but we will tailor the behavior change techniques used to the specific needs and determinants

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

Background Many biominerals form from amorphous calcium carbonate (ACC), but this phase is highly unstable when synthesised in its pure form inorganically. Several species of earthworm secrete calcium carbonate granules which contain highly stable ACC. We analysed the milky fluid from which granules form and solid granules for amino acid (by liquid chromatography) and functional group (by Fourier transform infrared (FTIR) spectroscopy) compositions. Granule elemental composition was determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and electron microprobe analysis (EMPA). Mass of ACC present in solid granules was quantified using FTIR and compared to granule elemental and amino acid compositions. Bulk analysis of granules was of powdered bulk material. Spatially resolved analysis was of thin sections of granules using synchrotron-based μ-FTIR and EMPA electron microprobe analysis. Results The milky fluid from which granules form is amino acid-rich (≤ 136 ± 3 nmol mg−1 (n = 3; ± std dev) per individual amino acid); the CaCO3 phase present is ACC. Even four years after production, granules contain ACC. No correlation exists between mass of ACC present and granule elemental composition. Granule amino acid concentrations correlate well with ACC content (r ≥ 0.7, p ≤ 0.05) consistent with a role for amino acids (or the proteins they make up) in ACC stabilisation. Intra-granule variation in ACC (RSD = 16%) and amino acid concentration (RSD = 22–35%) was high for granules produced by the same earthworm. Maps of ACC distribution produced using synchrotron-based μ-FTIR mapping of granule thin sections and the relative intensity of the ν2: ν4 peak ratio, cluster analysis and component regression using ACC and calcite standards showed similar spatial distributions of likely ACC-rich and calcite-rich areas. We could not identify organic peaks in the μ-FTIR spectra and thus could not determine whether ACC-rich domains also had relatively high amino acid concentrations. No correlation exists between ACC distribution and elemental concentrations determined by EMPA. Conclusions ACC present in earthworm CaCO3 granules is highly stable. Our results suggest a role for amino acids (or proteins) in this stability. We see no evidence for stabilisation of ACC by incorporation of inorganic components

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Meuse Vierlingsbeek 1977 Unio shell section.tif

<p>Thin section of an <em>Unio pictorum</em> from the river Meuse at Vierlingsbeek (the Netherlands) under reflected light.</p

Shell+oxygen isotopes.tif

Thesis Figure 1.6: A transverse section through a Unio tumidus shell and the shell aragonite δ18O (δ18Oar) record of the same specimen. Growth cessations, usually occurring in winter, are visible as dark internal growth lines in the shell and as narrow positive peaks in the shell δ18Oar record

Meuse Grevenbicht 1998 Unio shell section.tif

<p>Thin section of an <em>Unio pictorum</em> from the river Meuse at Grevenbicht (the Netherlands) under reflected light.</p

Shell specimens.pdf

Table 1 Specimens collected (data of the Bergen 1918) shell were previously published by Verdegaal et al. (2005) From: Versteegh, E.A.A., Vonhof, H.B., Troelstra, S.R., Kroon, D., 2011. Can shells of freshwater mussels (Unionidae) be used to estimate low summer discharge of rivers and associated droughts? International Journal of Earth Sciences 100(6): 1423-1432