Showing papers on "Trace metal published in 2013"

Controls of Trace Metals in Seawater

Abstract: This chapter presents a general overview of the major controls of trace metals in seawater, developed from the extensive research on trace metals over the last few decades. The reader should be given a first-order understanding and insight into trace metal biogeochemistry in the oceans, rather than presented with a comprehensive review of the distribution of each trace metal. Each of the trace metals discussed will undoubtedly prove to have unique characteristics and subtle differences from this version, yet the comparison with these characteristics will serve as a good springboard to a more complete understanding.

The Trace Metal Composition of Marine Phytoplankton

Abstract: Trace metals are required for numerous processes in phytoplankton and can influence the growth and structure of natural phytoplankton communities. The metal contents of phytoplankton reflect biochemical demands as well as environmental availability and influence the distribution of metals in the ocean. Metal quotas of natural populations can be assessed from analyses of individual cells or bulk particle assemblages or inferred from ratios of dissolved metals and macronutrients in the water column. Here, we review the available data from these approaches for temperate, equatorial, and Antarctic waters in the Pacific and Atlantic Oceans. The data show a generalized metal abundance ranking of Fe≈Zn>Mn≈Ni≈Cu≫Co≈Cd; however, there are notable differences between taxa and regions that inform our understanding of ocean metal biogeochemistry. Differences in the quotas estimated by the various techniques also provide information on metal behavior. Therefore, valuable information is lost when a single metal stoichi...

Trace Metal Interactions with Marine Phytoplankton

Abstract: Large spatial and temporal differences in both trace metal concentrations and chemical speciation in the sea have led to wide variations in biological availability of metals and their effects on phytoplankton. Trace metals are usually taken up by algae via the formation of coordination complexes with specialized transport ligands in their outer membranes, and metal uptake is determined by the interplay between redox, complexation, or oxide dissolution reactions of metals in seawater and ligand-exchange reactions at these sites. Some metals, such as copper and zinc, are heavily chelated by organic ligands in seawater, and their biological availability is determined by the concentrations of free metal ions or of kinetically labile inorganic species (free ions plus inorganic complexes). Once inside cells, trace metals influence metabolism primarily as a consequence of the role of many of these metals (Fe, Mn, Zn, Cu, Co, Mo, Ni) as essential cofactors in metalloenzymes. Trace metals may also inhibit ...

Degassing of Trace Volatile Metals During the 2001 Eruption of Etna

Abstract: This paper provides new data on sulfur, halogens, and minor and trace metal contents in airborne particulate matter from the Mt. Etna volcanic plume. Aerosol samples were collected by conventional filtration techniques before and during the summer 2001 eruption, in order to investigate relations between plume chemistry and volcano dynamics. Data analysis reveals that abundances of trace metals in the plume result from mixing of erosive and volatile components. The former is responsible for the contents of rare earth elements (REE), Ca, Ba, Sr, Ti, Sc, Y, Hf and Th; the latter contributes significantly to the abundance of Cs, Rb, Na and K, probably transported in the plume as metal halides, and Cd, Pb, Zn, Ge, Te, Mo, Re, Se, Sb, Sn, In, Bi, Tl, Cu and Au, associated with sulfur in plume particles. Enrichment factors show that plume particulate matter from the Monti Carcarazzi vent, which opened on the southern flank of the volcano in July 2001, is typically depleted in volatile trace elements with respect to the output from the summit crater, suggesting the secondary nature of the outpouring lavas. The decreasing trend observed throughout the eruption in the enrichment factors of most trace metals probably indicates a small-volume batch of magma with limited feed from depth.

Phytoremediation of bauxite-derived red mud by giant reed

Abstract: In 2010 the pond dam of an aluminium manufacturing plant in Hungary broke and flooded many towns with toxic red mud. At least 10 people were dead and over 150 hospitalized. Bauxite residue is often referred as red mud due to the colour of the bauxite ore and iron oxides. Red mud is separated during the refining process. The production of 1 t of alumina generally results in the creation of 1–1.5 t of red mud. Red mud is toxic for the environment due to high alkalinity, salinity and trace metals. Here, we used the plant Arundo donax L. (giant reed) to uptake trace metals and decrease salinity and pH of red mud. We measured plant toxicity, trace metal availability and biomass production. Results show a 25 % decrease in electrical conductivity of red mud and a 6 % decrease in electrical conductivity of mud-polluted soil. Giant reed cultivation decreases available Cd, Pb, Co, Ni and Fe. Biomass of giant reed seedlings in red mud and mud/control soil mixture was increased by 40.4 and 47.2 %, respectively, comparing with control soil. Our findings show that giant reed is promising to decontaminate soils contaminated by red mud.

Aerosol size-resolved trace metal composition in remote northern tropical Atlantic marine environment: case study Cape Verde islands

Abstract: . Size-resolved trace metal concentrations of 15 elements in aerosol particles at the Cape Verde Atmospheric Observatory (CVAO) under remote background conditions were investigated through analysis of aerosol samples collected during intensive field studies from January 2007 to November 2011 using total reflection x-ray fluorescence (TXRF). The identification of the main air mass origin that influence remote marine aerosol in the northern tropical Atlantic has been investigated. In total, 317 samples were collected. The dataset was analyzed according to the main air mass inflow at the station. We found that remote conditions make up about 45% of the meteorological conditions in a year at CVAO and thus the northern tropical Atlantic. Surprisingly, air masses from North America are often responsible for higher trace metal concentrations in this region. Elements such as Zn, Pb, Cu, Cr, Ni, and V were mostly found in the submicron size fractions, while elements with dominant crustal or oceanic origin such as Fe, Ti, Mn, Sr, and Rb were found in the coarse fractions (>1 μm). The highest metal concentrations, especially for Zn (3.23 ng m−3), Cu (0.81 ng m−3), Sr (2.63 ng m−3), and Cr (0.53 ng m−3), were observed in air masses originating from North America and the concentrations were within the same concentration range to those reported previously in the literature for remote marine aerosols. Fe (12.26 ng m−3), Ti (0.91 ng m−3), and Mn (0.35 ng m−3) showed higher concentrations when air mass came from Europe and the Canary Islands. Pb concentration was low ( 20) for Zn, Cu, Ni, Cr, Pb, and Se. The observed enrichment of the elements was attributed to crustal, marine, anthropogenic, and biogenic sources, as well as long-range transport and resuspension. Zn, Cu and Pb were indicators of anthropogenic activities, while Ti and Sr were indicators of crustal and marine origin, respectively. Oceanic and biogenic emissions might have contributed to most of the Se observed. This work provides the first long-term size-resolved trace metals study for remote tropical northern Atlantic marine aerosols and the dataset could serve as good initiation of yearly flux estimates.

Iron fluxes from the shelf regions near the South Shetland Islands in the Drake Passage during the austral-winter 2006

Abstract: Spatial distributions of dissolved iron (Fe), manganese (Mn) and aluminum (Al) in the upper 500 m of the water column near the Antarctic Peninsula (AP) during the 2006 austral-winter are consistent with diagenetically-produced sedimentary sources and are somewhat higher than data obtained in this region during the 2004 austral-summer. In contrast, surface phytoplankton abundances were 6–7 times lower relative to the 2004 austral-summer. Near the South Shetland Islands elevated levels of dissolved Al, Fe and Mn were found corresponding to high loads of resuspended material above the shelf as indicated by the transmissometer signal. Despite these high levels of trace metals, phytoplankton abundances in this area were lower than in the offshore Antarctic Circumpolar Current (ACC) waters. Offshore ACC stations had low concentrations of Fe, but up to five times greater abundance of phytoplankton. The difference in phytoplankton abundance between the regions seems largely driven by light availability, as indicated by mixed layer depths. The elevated trace metal concentrations near King George Island in the Bransfield Strait (BS) correspond to the flow path of the Bransfield Current. This enriched plume can also be seen exiting the BS, between Clarence and Elephant islands into the Ona Basin where it mixes with high nutrient low trace metal concentration ACC waters leading to high productivity in this region and further downstream in the Scotia Sea during the growing season.

Levels and distribution of trace metals in surface sediments from Kongsfjorden, Svalbard, Norwegian Arctic

Abstract: Trace metal contents (Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn) have been measured in 27 surface sediment samples collected from Kongsfjorden, Svalbard, Norwegian Arctic. The analyses yielded concentration values (in mg kg−1) of 0.13–0.63 for Cd, 11.89–21.90 for Co, 48.65–81.84 for Cr, 21.26–36.60 for Cu, 299.59–683.48 for Mn, 22.43–35.39 for Ni, 10.68–36.59 for Pb, 50.28–199.07 for Zn and 8.09–65.34 for Hg (in ng g−1), respectively. Relative cumulative frequency method has been used to define the baseline values of these metals, which (in mg kg−1) were 0.14 for Cd, 13.56 for Co, 57.86 for Cr, 25.14 for Cu, 364.08 for Mn, 26.22 for Ni, 17.46 for Pb, 70.49 for Zn and 9.76 for Hg (in ng g−1), respectively. The enrichment factor analysis indicated that Hg showed some extent of anthropogenic pollution, while Pb, Zn and Cd showed limited anthropogenic contamination in the study areas.

Impact of western Siberia heat wave 2012 on greenhouse gases and trace metal concentration in thaw lakes of discontinuous permafrost zone

Abstract: During the anomalously hot summer in 2012, surface air temperatures in Western Siberia were 5 to 15 °C higher than those observed during the previous period of > 30 yr. This unusual climate phenomenon provided an opportunity to examine the effects of short-term natural heating of water in thermokarst ponds and lakes in discontinuous permafrost zones and compare these observations to previous field results obtained when the temperature was normal during the summer of 2010 in the same region. In 2012, thermokarst bodies of water shrank significantly, water levels dropped approximately 50 cm in large lakes and small ( 2 ) ponds, and shallow soil depressions disappeared. Based on samples from ~ 40 bodies of water collected previously and in 2012, first-order features of changes in chemical composition in response to increased water temperatures (from 14.1 ± 2.2 to 23.8 ± 2.3 °C in 2010 and 2012, respectively) were established. In these thermokarst bodies of water that covered a full range of surface areas, the average conductivity and pH were almost unchanged, whereas dissolved organic carbon (DOC), Cl - and SO 4 2- concentrations were higher by a factor of ~ 2 during summer 2012 compared to periods with normal temperatures. Similarly, most divalent metals and insoluble trivalent and tetravalent elements were more concentrated by a factor of 1.7–2.4 in the summer of 2012 than normal periods. The average concentrations of dissolved CO 2 and CH 4 during the hot summer of 2012 increased by factors of 1.4 and 4.9, respectively. For most of the trace elements bound to colloids, the degree of colloidal binding decreased by a factor of 1.44 ± 0.33 (for an average of 40 elements) during the hot summer of 2012 compared to normal periods. Increases in CO 2 and CH 4 concentrations with the decreasing size of the body of water were well-pronounced during the hot summer of 2012. The concentrations of CO 2 and CH 4 rose by factors of 5 and 150, respectively, in small (≤ 10 2 m 2 ) compared to large (≥ 10 4 m 2 ) thermokarst (thaw) lakes. Taken together, these trends suggest that, for a conservative scenario of lake size distribution, lake water warming at high latitudes will produce (1) a significant increase in methane emission capacity from thaw lake surfaces; (2) decreased molecular sizes of trace element complexes and potential bioavailability of metal micronutrients in water columns; and (3) relatively conservative responses by CO 2 , DOC and trace element concentrations.