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[1] Black carbon (BC), the product of incomplete combustion of fossil fuels and biomass (called elemental carbon (EC) in atmospheric sciences), was quantified in 12 different materials by 17 laboratories from different disciplines, using seven different methods. The materials were divided into three classes: (1) potentially interfering materials, (2) laboratory-produced BC-rich materials, and (3) BC-containing environmental matrices (from soil, water, sediment, and atmosphere). This is the first comprehensive intercomparison of this type (multimethod, multilab, and multisample), focusing mainly on methods used for soil and sediment BC studies. Results for the potentially interfering materials (which by definition contained no fire-derived organic carbon) highlighted situations where individual methods may overestimate BC concentrations. Results for the BC-rich materials (one soot and two chars) showed that some of the methods identified

When glaciers retreat they expose barren substrates that become colonized by organisms, beginning the process of primary succession. Recent studies reveal that heterotrophic microbial communities occur in newly exposed glacial substrates before autotrophic succession begins. This raises questions about how heterotrophic microbial communities function in the absence of carbon inputs from autotrophs. We measured patterns of soil organic matter development and changes in microbial community composition and carbon use along a 150-year chronosequence of a retreating glacier in the Austrian Alps. We found that soil microbial communities of recently deglaciated terrain differed markedly from those of later successional stages, being of lower biomass and higher abundance of bacteria relative to fungi. Moreover, we found that these initial microbial communities used ancient and recalcitrant carbon as an energy source, along with modern carbon. Only after more than 50 years of organic matter accumulation did the soil microbial community change to one supported primarily by modern carbon, most likely from recent plant production. Our findings suggest the existence of an initial stage of heterotrophic microbial community development that precedes autotrophic community assembly and is sustained, in part, by ancient carbon.

Turnover of carbon in soils is the dominant flux in the global carbon cycle and is responsible for transporting 20 times the quantity of anthropogenic emissions each year. This paper investigates the potential for soils to be modified with calcium rich materials (e.g. demolition waste or basic slag) to capture some of the transferred carbon as geologically stable calcium carbonate. To test this principal, artificial soil known to contain calcium rich minerals (calcium silicates and portlandite) was analysed from two sites across North East England, UK. The results demonstrate an average carbon content of 30±15.3 Kg C m -2 stored as calcium carbonate, which is three times the expected organic carbon content and has accumulated at a rate of 25 ± 12.8 t C ha -1 y -1 since 1996. Isotopic analysis of the carbonates gave values between -6.4 and -27.5‰ for δ 13 C and -3.92 and -20.89‰ for  18 O respectively (against V-PDB), which suggests that a combination of carbonate formation mechanisms are operating including the hydroxylation of gaseous CO 2 in solution, the sequestration of degraded organic carbon with minor remobilisation/precipitation of lithogenic carbonates. This study implies that construction/development sites may be designed with a carbon capture function to sequester atmospheric carbon into the soil matrix with a maximum global potential of 290 Mt C y -1 .

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Minerals stabilize organic carbon (OC) in sediments, thereby directly affecting global climate at multiple scales, but how they do it is far from understood. Here we show that manganese oxide (Mn oxide) in a water treatment works filter bed traps dissolved OC as coatings build up in layers around clean sand grains at 3%w/wC. Using spectroscopic and thermogravimetric methods, we identify two main OC fractions. One is thermally refractory (>550 °C) and the other is thermally more labile (<550 °C). We postulate that the thermal stability of the trapped OC is due to carboxylate groups within it bonding to Mn oxide surfaces coupled with physical entrapment within the layers. We identify a significant difference in the nature of the surface-bound OC and bulk OC . We speculate that polymerization reactions may be occurring at depth within the layers. We also propose that these processes must be considered in future studies of OC in natural systems.

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All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. B lack carbon produced by incomplete combustion of fossil fuels and biomass, is a ubiquitous form of ROM widely distributed in the environment. There is no a unique structure accepted for this complex material. Heidenreich et al. (1968) reported for the fi rst time the "onion-like" concentric microtexture of "carbon black." In general, it is accepted that black carbon consists of complex polyaromatic condensed structures