Chloro- and Bromoacetates in Natural Archives of Firn from Antarctica

Abstract

A firn core was drilled in Dronning Maud Land, Antarctica, to investigate the presence of haloacetates in snow that had accumulated over the past 200 years. By employing GC-MS detection of methyl esters of haloacetic acids, we were able to measure haloacetate concentrations down to one or a few nanograms per liter. Trichloroacetate (TCA) and dibromoacetate (DBA) were found in firn at concentrations that clearly exceeded the blank level of the applied analytical procedure, with mean concentrations estimated to 12 and 6 ng/L, respectively. There were also indications that mono-and dichloroacetate (MCA and DCA) were present in firn, whereas monobromoacetate (MBA) was found only in samples of surficial snow. We concluded that there is a significant natural background level of TCA and DBA in precipitation based on the following: (i) several of samples represented snow accumulated in the 19th century; (ii) haloacetates can be expected to be immobile in Antarctic firn; (iii) extensive measures were taken to prevent sample contamination; and (iv) blank levels of the analytical procedure used were low and stable. In addition, our results suggested that MCA and DCA also occur naturally in precipitation.

Bromine species fluxes from Lake Constance’s catchment, and a preliminary lake mass balance

“…We are currently unaware of any studies showing natural production of bromate, and thus are unsure how this species could be formed under natural conditions. Bromoacetic acid has been observed in rainfall in Germany and other areas around the world, and seems to be naturally produced, although the mechanism is still largely unknown (Von Sydow et al, 2000;Rö mpp et al, 2001;Scott et al, 2005). The maximum concentration of this species was 1.6 lg l À1 as Br, observed in the Steinach.…”

Formation of chloroacetic acids from soil, humic acid and phenolic moieties

“…A firn core from Antarctica with snow accumulated from the past 200 years exhibits haloacetic acids even in Chemosphere 52 (2003) [513][514][515][516][517][518][519][520] www.elsevier.com/locate/chemosphere preindustrial layers (von Sydow et al, 2000). Moreover, TCA is also present in glacier ice of preindustrial origin from Northern Sweden (von Sydow et al, 1998) and in glacier ice samples from Monte Rosa, Switzerland (Haiber et al, 1996), dated around 1900, from the time before the mass production of chlorinated solvents, indicating that natural sources must also exist.…”

Biological Effects and Biosynthesis of Brominated Metabolites

“…Trichloromethane is formed during aqueous chlorination of a range of phenols including 2,4,6-trichlorophenol [58], and tribromomethane during chlorination of water containing natural organic matter in the presence of bromide. Since 2,4,6-tribromophenol is formed from phenol by the action of the chloroperoxidase from Notomastus lobatus (section "Enzymes") in the presence ofbromide and H 2 0 2 [22] it is plausible to suggest that this could be an alternative source of tribromomethane, brominated acetones ( e.g., 54) that are found in the alga Asparagopsis taxiformis and dibrominated acetate that has been found in archival firn from Antarctica [220] (Fig.12). 2.…”