Organic tracers from biomass burning in atmospheric particulate matter over the ocean

Particulate matter from the atmosphere over the Atlantic Ocean along the South American and African Continents has been analyzed for organic tracers from natural and biomass burning emissions. The major biomarker compounds characterized are natural products from continental vegetation consisting primarily of epicuticular wax components. For example, n-alkanes ranged from C₂₅ to C₃₅, with an odd carbon number predominance and carbon maxima (C_max) at 29 or 31. Concentrations of n-alkanes varied from 0.3 to 680 ng/m³. Nevertheless, n-alkanols are the dominant terrestrial tracers in almost all samples (concentrations from 0.1 to 780 ng/m³) and ranged from C₂₂ to C₃₄ with an even carbon number predominance. Despite the major presence of the natural tracers, organic components from biomass burning emissions are also present in the particulate matter. The major tracers from this source are thermal degradation products from the biopolymer cellulose, namely the dianhydromonosaccharide derivatives levoglucosan, galactosan, and mannosan. In general, the concentrations of levoglucosan, the major derivative from this source in all samples, varied from 0.0008 to 0.15 ng/m³ in atmospheric samples collected over the ocean and from 0.04 to 4860 ng/m³ in terrestrial particulate matter, used as reference in this study. Dehydroabietic acid, another marker compound emitted from burning of Gymnosperm fuel, is also detectable in most oceanic samples at concentrations ranging from 0.0001 to 0.4 ng/m³, whereas in terrestrial aerosol particulate matter, this component is present at much higher concentrations (0.23–440 ng/m³). The presence of these tracers in atmospheric particulate matter over the ocean confirms the long-range transport of smoke from biomass burning off the continents.     

Africa and the Green Climate Fund: current challenges and future opportunities

Although the Green Climate Fund (GCF) is widely commendable in several ways, access to the Fund has been very challenging for many African countries. Using GCF published statistics, we identify possible challenges likely to be responsible for this. First, we present an assessment of the GCF’s Readiness Support Programme with respect to how the programme’s performance may have affected achievement of African countries’ readiness outcomes. Second, a critical evaluation of the status of African GCF portfolio (pipeline and approved projects) provides a means by which to assess how well Africa’s current portfolio aligns with GCF strategic impact areas, results areas and investment priorities. We then discuss GCF access modalities and the implications of relying on International Accredited Entities (IAEs) to indirectly access the Fund. The readiness support assessment indicates that the distribution of support requests and funding approvals is nearly equal across the regions of Africa, Asia Pacific and Latin America and the Caribbean. However, when the regions are considered individually, Africa demonstrates lower approvals with respect to requests and securing funding. Results from the GCF portfolio evaluation reveal that little or no attention has been devoted to GCF critical result areas such as forests and land use or transport, where great potentials for low-carbon development transitions exist. With respect to access modalities, the IAE financing mechanism currently provides access to the Fund for the majority of projects in both the global and African GCF portfolios. The implications of these findings are extensively discussed.

Key policy insights

• For Africa, limited readiness support and a reliance on International Accredited Entities constrains capacity building, thereby reinforcing a lack of both readiness and direct access to the GCF.

• There are opportunities for Africa to diversify its GCF portfolios, adhere to international commitments, and address its adaptation and development needs by identifying and capitalizing on linkages between GCF funding priorities, mitigation, and adaptation.

• There are leverage points within existing climate finance and governance systems that could catalyse a shift in Africa’s engagement with the GCF and generate positive, cascading effects on institutional strengthening, direct access accreditation and securing funding.

     

Pollutant concentrations in fog and low cloud water at selected sites of the Czech Republic

In this paper, the basic composition of fog and low cloud water are presented, resulting from the analyses of water samples from 111 fog/cloud events. The samples were collected at five sites located in various regions of the Czech Republic. Two sampling sites are in mountainous regions and three sites represent various urban areas. The mountain stations are located in two regions of the Czech Republic with different industry types. At all the sites, active fog collectors were employed. In the water samples, the conductivity, acidity (pH), cations (H⁺, Na⁺, K⁺, NH₄⁺, Mg²⁺, Ca²⁺) and anions (F⁻, Cl⁻, NO₃⁻, SO₄²⁻) were determined.A mean pH value of about 4.5 was obtained at mountain sites whereas the measurements in urban areas showed mean pH values from 4.9 to 6.4. The mean conductivity values in the samples from the two mountain stations were 137 and 191.5 μS cm⁻¹. The samples from urban sites showed mean values between 127.7 and 654.4 μS cm⁻¹. The maximum concentration means for the three dominant pollutants (expressed by the ratio mountain sites/urban sites) are 32.9/99.6 mg l⁻¹ for NO₃⁻, 32.5/192.9 mg l⁻¹ for SO₄²⁻ and 18.5/52.7 mg l⁻¹ for NH₄⁺. As expected, we found higher ion concentrations in the northern part of the Czech Republic where larger numbers of lignite-burning power plants, chemical factories and opencast lignite mines are located. A decrease in ion concentrations was observed at higher altitude sites, probably reflecting at least in part higher liquid water contents at these locations.     

Macrofossil evidence of alder (Alnus sp.) in Britain early in the Late Glacial Interstadial: implications for the northern cryptic refugia debate

Wood macrofossil remains of alder and willow/poplar have been recovered from a sediment sequence in the valley of the Turker Beck in the Vale of Mowbray, North Yorkshire. These remains have yielded radiocarbon dates early in the Devensian Late Glacial (14.7–14k cal a bp ), equivalent to the early part of the Greenland Interstadial (GI-1e) of the GRIP ice-core record. These are the earliest dates recorded for the presence of alder in the Late Glacial in the British Isles. Associated biological remains have provided a palaeoenvironmental record for this early part of the Greenland Interstadial, generally indicative of open environments dominated by herbaceous taxa on both the wetland and dryland surfaces. However, stands of alder, birch and willow woodland were also present, and indicate the possibility that such tree species survived in cryptic refugia in Britain as elsewhere in northern Europe during the Last Glacial Maximum. The absence of alder pollen at Turker Beck, in a sequence in which its macrofossil remains are relatively abundant, lends support to the view that pollen can be a poor indicator of the presence of tree species in Late Glacial sequences in northern and western Europe.     

Early Wisconsinan (MIS 4) Arctic ground squirrel middens and a squirrel-eye-view of the mammoth-steppe

Fossil arctic ground squirrel (Spermophilus parryii) middens were recovered from ice-rich loess sediments in association with Sheep Creek-Klondike and Dominion Creek tephras (ca 80 ka) exposed in west-central Yukon. These middens provide plant and insect macrofossil evidence for a steppe-tundra ecosystem during the Early Wisconsinan (MIS 4) glacial interval. Midden plant and insect macrofossil data are compared with those previously published for Late Wisconsinan middens dating to ～25–29¹⁴C ka BP (MIS 3/2) from the region. Although multivariate statistical comparisons suggest differences between the relative abundances of plant macrofossils, the co-occurrence of steppe-tundra plants and insects (e.g., Elymus trachycaulus, Kobresia myosuroides, Artemisia frigida, Phlox hoodii, Connatichela artemisiae) provides evidence for successive reestablishment of the zonal steppe-tundra habitats during cold stages of the Late Pleistocene. Arctic ground squirrels were well adapted to the cold, arid climates, steppe-tundra vegetation and well-drained loessal soils that characterize cold stages of Late Pleistocene Beringia. These glacial conditions enabled arctic ground squirrel populations to expand their range to the interior regions of Alaska and Yukon, including the Klondike, where they are absent today. Arctic ground squirrels have endured numerous Quaternary climate oscillations by retracting populations to disjunct “interglacial refugia” during warm interglacial periods (e.g., south-facing steppe slopes, well-drained arctic and alpine tundra areas) and expanding their distribution across the mammoth-steppe biome during cold, arid glacial intervals.     

Bridges and bottlenecks: Andrei Sher’s role in the development of international collaboration in Beringian science

Andrei Sher played a leading role in the development of international cooperation and exchange of ideas in Beringian science. The Cold War created great tensions between the USSR and the NATO countries, as the Bering Strait region became one of the front lines of potential military conflict. However, through the persistent efforts of such people as Andrei Sher in Russia and David Hopkins in the USA, scientists were able to overcome political obstacles to attend international Beringian conferences, visit each other’s militarized zones to do fieldwork, and collaborate on joint projects.     

The circumvention of the natural biopurification of calcium along nutrient pathways by atmospheric inputs of industrial lead

Biopurification factors for Ca with respect to Sr, Ba, and natural, uncontaminated Pb were measured for different nutrient-consumer pairs in a remote subalpine ecosystem. The factor for Sr is expressed as: (nutrient $\text{Sr}\text{Ca}$) ÷ (consumer $\text{Sr}\text{Ca}$). Similar expressions were used for $\text{Ba}\text{Ca}$ and $\text{Pb}\text{Ca}$. It was found that Ca was biopurified of Sr 3-fold, of Ba 16-fold, and of Pb 100-fold in going from rock to sedge leaves. In going from sedge leaf to vole, Ca was biopurified of Sr 4-fold, of Ba 8-fold, and of Pb 16-fold. In going from meadow vole to pine marten, Ca was biopurified of Sr 6-fold, of Ba 7-fold, and of Pb 1.1-fold. Similar ranges of values for these factors were obtained for detrital and amphibian food chains. Fluxes of industrial lead entering the ecosystem as precipitation and dry deposition were measured and it was found that 40% of the lead in soil humus and soil moisture, 82% of the lead in sedge leaves, 92% of the lead in vole, and 97% of the lead in marten was industrial. The natural skeletal $\text{Pb}\text{Ca}$ ratio in carnivores (4 × 10^?8) was determined by means of corrections for inputs of industrial lead, food chain relationships, and measured biopurification factors for the ecosystem studied. This represents a 1700-fold reduction of the average $\text{Pb}\text{Ca}$ ratio in igneous rocks at the earth's surface (6.4 × 10^?5) by the compounding of successive Pb biopurification factors in transferring Ca from rock to carnivore. The natural ratio is similar to the value of 6 × 10^?8 observed for $\text{Pb}\text{Ca}$ in the bones of Peruvians who lived 2000 years ago but is 1/900th of the value of about 3.5 × 10^?5 for the skeletal $\text{Pb}\text{Ca}$ ratio found in present day Americans.This study shows experimentally how the $\text{Ba}\text{Ca}$ ratio in average surface igneous rock (3 × 10^?3) has been reduced 800-fold through compounding of successive biopurification steps to provide the skeletal $\text{Ba}\text{Ca}$ ratio of about 4 × 10^?6 observed in humans. It also provides biopurification factors for Sr and Ba among a number of nutrient-consumer pairs which anthropologists can use to delineate degrees of herbivory in diets of hominids within the last 10,000 years.     

Cementation of kerogen-rich marls by alkaline fluids released during weathering of thermally metamorphosed marly sediments. Part II: Organic matter evolution,magnetic susceptibility and metals (Ti,Cr, Fe) at the Khushaym Matruk natural analogue (Central Jordan)

Spontaneous combustion, less than 1 Ma ago, affected a 60-m thick sediment pile of biomicrite at the Khushaym Matruck site (Jordan). The present study shows that three retrograde alteration stages occurred: weathering, thermal stress and oxidative alkaline perturbation. μ-FT-i.r. spectra of isolated kerogens and oxygen index of whole rocks indicate that oxidation of organic matter occurred down to ∼10 m beneath the metamorphosed zone at Khushaym Matruck. The occurrence of the oxidative weathering bacterially mediated, as suggested by the mass chromatograms of saturated hydrocarbons, can explain high Rock-Eval T_max values and low petroliferous potential measured along the sedimentary pile. On the other hand, the thermal extent of combustion events was limited to the first 2 m from the contact. The mean reflectance of 0.20–0.24% and porosity of ca. 50% of the grey clayey biomicrites indicate that organic matter was very immature and sediments were unconsolidated at the time of the combustion event. Using mineralogy, microscopic analyses of vegetable debris and magnetic susceptibility, a suite of characteristic points corresponding to the thermal imprint can be assessed: (i) x = 0m, T ∼ 1000 °C, (ii) x = 1 m, T ∼ 350 °C, (iii) x = 2 m, T ∼ 150 °C and (iv) x > ∼ 8 m, T ∼ 30 °C. Paleocirculation of meteoric groundwater in the ‘cement-marbles’ generated high-pH fluids that have circulated via fractures and through the matrix porosity of the underlying biomicrites but have also induced alkaline hydrolysis and oxidative attack of the organic matter. The polysaccharide/lignin ratio derived from μ-FT-i.r. analyses shows that the delignification of vegetable debris and degradation of polysaccharides progressively decline in the indurated zone, which indicates a decrease in the pH of migrating solutions. The latter also severely oxidized organic matter at 2.10 and 3.05 m as revealed by the oxygen index and induced the generation of bitumen. The spatial correlation between the oxidation levels of organic matter and the metal contents (Fe, Ti and Cr) suggests that redox reactions were responsible for the immobilization of metals in the indurated biomicrites. The intensity of these reactions is attributed to changes in the fluid flow regime within the sedimentary column.     

Separation between Gould Belt and Disk Stars in the Solar Neighbourhood

The adoption of a parametric model for the spatial distribution of Gould Belt and Galactic Disk stars allows the classification by their membership probabilities of stars from the Hipparcos catalogue in the Solar vicinity and the estimation of structural parameters for both stellar systems for several age groups. The observed kinematics of Gould Belt and Disk stars are shown to be different. This revised version was published online in July 2006 with corrections to the Cover Date.