Chemical characterization of marine sub-micrometer aerosol particles during the MERIAN cruise MSM18/3 from the Cape Verde island Sao Vicente to Gabun (Atlantic Ocean)

Sub-micron marine aerosol particles (PM1) were collected during the MERIAN cruise MSM 18/3 between 22 June 2011 and 21 July 2011 from the Cape Verde island Sao Vicente to Gabun crossing the tropical Atlantic Ocean and passing equatorial upwelling areas. According to air mass origin and chemical composition of the aerosol particles, three main regimes could be established. Aerosol particles in the first part of the cruise were mainly of marine origin, in the second part was marine and slightly biomass burning influenced (increasing tendency) and in the in last part of the cruise, approaching the African mainland, biomass burning influences became dominant. Generally aerosols were dominated by sulfate (caverage = 1.99 µg/m**3) and ammonium ions (caverage = 0.72 µg/m**3) that are well correlated and slightly increasing along the cruise. High concentrations of water insoluble organic carbon (WISOC) averaging 0.51 µg/m**3 were found probably attributed to the high oceanic productivity in this region. Water soluble organic carbon (WSOC) was strongly increasing along the cruise from concentrations of 0.26 µg/m**3 in the mainly marine influenced part to concentrations up to 3.3 µg/m**3 that are probably caused by biomass burning influences. Major organic constituents were oxalic acid, methansulfonic acid (MSA) and aliphatic amines. MSA concentrations were quite constant along the cruise (caverage = 43 ng/m**3). While aliphatic amines were more abundant in the first mainly marine influenced part with concentrations of about 20 ng/m**3, oxalic acid showed the opposite pattern with average concentrations of 12 ng/m**3 in the marine and 158 ng/m**3 in the biomass burning influenced part. The alpha dicarbonyl compounds glyoxal and methylglyoxal were detected in the aerosol particles in the low ng/m**3 range and followed oxalic acid closely. MSA and aliphatic amines accounted for biogenic marine (secondary) aerosol constituents whereas oxalic acid and the alpha dicarbonyl compounds were believed to result mainly from biomass burning. N-alkane concentrations increased along the cruise from 0.81 to 4.66 ng/m**3, PAHs and hopanes were abundant in the last part of the cruise (caverage of PAHs = 0.13 ng/m**3, caverage of hopanes = 0.19 ng/m**3). Levoglucosan was identified in several samples of the last part of the cruise in concentrations around 2 ng/m**3, pointing to (aged) biomass burning influences. The investigated organic compounds could explain 9.5% of WSOC in the mainly marine influenced part (dominating compounds: aliphatic amines and MSA) and 2.7% of WSOC in the biomass burning influenced part (dominating compound: oxalic acid) of the cruise.

Geographical variation in shell morphology of juvenile snails (Concholepas concholepas) along the physical-chemical gradient of the Chilean coast

Changes in phenotypic traits, such as mollusc shells, are indicative of variations in selective pressure along environmental gradients. Recently, increased sea surface temperature (SST) and ocean acidification (OA) due to increased levels of carbon dioxide in the seawater have been described as selective agents that may affect the biological processes underlying shell formation in calcifying marine organisms. The benthic snail Concholepas concholepas (Muricidae) is widely distributed along the Chilean coast, and so is naturally exposed to a strong physical-chemical latitudinal gradient. In this study, based on elliptical Fourier analysis, we assess changes in shell morphology (outlines analysis) in juvenile C. concholepas collected at northern (23°S), central (33°S) and southern (39°S) locations off the Chilean coast. Shell morphology of individuals collected in northern and central regions correspond to extreme morphotypes, which is in agreement with both the observed regional differences in the shell apex outlines, the high reclassification success of individuals (discriminant function analysis) collected in these regions, and the scaling relationship in shell weight variability among regions. However, these extreme morphotypes showed similar patterns of mineralization of calcium carbonate forms (calcite and aragonite). Geographical variability in shell shape of C. concholepas described by discriminant functions was partially explained by environmental variables (pCO2, SST). This suggests the influence of corrosive waters, such as upwelling and freshwaters penetrating into the coastal ocean, upon spatial variation in shell morphology. Changes in the proportion of calcium carbonate forms precipitated by C. concholepas across their shells and its susceptibility to corrosive coastal waters are discussed.

(Table 1) Chemical compositions of beryllium in sediments and pore waters of ODP Hole 131-808

Studies of Be distributions in subduction zone sediments will help to understand questions regarding the enrichments of cosmogenic Be-10 in arc volcanic rocks. Analyses of Be-10 and Be-9 in sediments of Ocean Drilling Program Site 808, Nankai Trough and Be-9 in porewaters of Site 808 and Sites 671 and 672, Barbados ridge complex, show significant decreases in solid phase Be-10 and large increases of porewater Be-9 at the location of the décollement zone and below or at potential flow conduits. These data imply the potential mobilization of Be during pore fluid expulsion upon sediment burial. Experiments involving reaction between a décollement sediment and a synthetic NaCl-CaCl2 solution at elevated pressure and temperatures were conducted in an attempt to mimic early subduction zone processes. The results demonstrate that Be is mobilized under elevated pressure and temperature with a strong pH dependence. The Be mobilization provides an explanation of Be-10 enrichment in arc volcanic rocks and supports the argument of the importance of the fluid processes in subduction zones at convergent margins.