Cadmium/Calcium and stable isotope ratios of benthic foraminifera from the northeast Atlantic Ocean

The delta13C and Cd measurements from benthic foraminifera from Biogeochemical Ocean Flux Study (BOFS) northeast Atlantic Ocean sediment cores are presented. The delta13C values in glacial foraminifera are consistent with those from elsewhere in the North Atlantic Ocean. For intermediate water (1000 - 2000 m water depth), delta13C values were higher at the last glacial maximum than in present North Atlantic Deep Water (NADW), whereas for deep water (>2000 m) they were lower during the glacial maximum. The Cd concentrations of glacial northeast Atlantic intermediate water were lower than those of present NADW. However, deepwater Cd concentrations increased to values between NADW and present Pacific Deep Water (PDW). The delta13C and Cd data are consistent and show that the northeast Atlantic Ocean was strongly stratified with 13C enriched, low Cd intermediate water overlying 13C depleted, high Cd deep water. The glacial water column comprised two different water masses: deep water, similar in character to present Antarctic Bottom Water (AABW), and intermediate water, different in character from both AABW and NADW, and any present intermediate-depth North Atlantic water. The characteristics of glacial intermediate water were, however, similar to present near-surface waters in the North Atlantic, which suggests rapid ventilation of the glacial ocean to depths of up to 2000 m by cold, nutrient-depleted young surface waters.

Composition of soil samples from injection location

CO2 leakage from subsurface storage sites is one of the main concerns connected with the CCS technology. As CO2 leakages into near surface formations appear to be very unlikely within pilot CCS projects, the aim of this work is to emulate a leakage by injecting CO2 into a near surface aquifer. The two main questions pursued by the injection test are (1) to investigate the impact of CO2 on the hydrogeochemistry of the groundwater as a base for groundwater risk assessment and (2) to develop and apply monitoring methods and monitoring concepts for detecting CO2 leakages in shallow aquifers. The presented injection test is planned within the second half of 2010, as a joint project of the University of Kiel (Germany), the Helmholtz-Centre for Environmental Research (Leipzig, Germany) and the Engineering Company GICON (Dresden, Germany). The test site has been investigated in detail using geophysical methods as well as direct-push soundings, groundwater well installation and soil and groundwater analyses. The present paper presents briefly the geological and hydrogeological conditions at the test site as well as the planned injection test design and monitoring concept.