Portion Of Carbon Research Articles

Effects of different nitrogen sources on the production of Hyaluronic acid by Streptococcus

Hyaluronic acid (HA) is a linear polysaccharide with high molecular weight composed of disaccharide units of D-glucuronic acid (GlcUA) and N-acetylglucosamine (GlcNAc). HA is naturally present in vertebrate organisms, as well as in bacteria. HA can be obtained commercially through three routes: human umbilical cords, rooster combs, and strains of group C Streptococcus .T his is an atural polysaccharide with extensive range of applications in the medical, pharmaceutical and cosmetics. Due to the viscoelastic and hydrophilic, the HA products and derivatives present high aggregated value ranging from US$ 2000 to 60000 Kg -1 , depending on their applications. The most frequently used bacteria in the industrial production of HA are Lancefield group A and C streptococci. These bacteria are nutritionally fastidious microorganisms which require complex nutrients due to their limited ability to synthesize specific aminoacids and B-vitamins. Additionally, there is the nutritional requirement with respect to organic nitrogen, which also supplies a large portion of carbon for their cellular biosynthesis. Recent studies seek alternatives to allow the cost of production of HA using agricultural derivatives and industrial waste. In this context, the objective of this study was to evaluate the effect of nitrogen sources yeast extract, soy protein, whey protein and corn steep liquor in the production of HA. Fermentations were carried out in 125 mL erlenmeyer flasks containing 25 mL culture medium. The culture medium comprised in ( gL -1 ): glucose, 30; nitrogen source (yeast extract, soy protein, whey protein or corn steep liquor), 30; K2HPO4 ,2 .5, NaCl, 2,0 and MgSO4 ,1 .5. The inoculum was 10% (v/v) and the fermentations occurred at 100 rpm, 37°C and pH 8.0 for 24 hours. The fermented medium was centrifuged and the cell free supernatant was treated with ethanol for the precipitation of HA which quantified using a colorimetric reagent Carbazole. The concentration of lactic acid, acetic acid and formic acid were also analyzed in a system of high performance liquid chromatography with IR detector, column Aminex HPX 87H at 60°C and a solution of H2SO4 0.005 mol L -1 as the mobile phase a flow rate of 0.7 mL min -1 . The results performed in triplicate were compared by the Tukey test at 5% probability level (p < 0.05). The highest production of HA, 0.534 g L -1 was obtained when using yeast extract as nitrogen source. Subsequently, experiments which resulted in a better yield of the polymer are those containing soybean protein (0.192 g.L -1 ) and whey protein ( 0.063 g.L -1 ). In medium containing corn steep liquor, no microbial growth or production of HA ocurred. The decreased production of HA was directly followed by a reduction of the production of lactic acid and acetic acid.

Patrones de distribución y tasas de bioerosión del erizo &lt;i&gt;Centrostephanus coronatus&lt;/i&gt; (Diadematoida: Diadematidae), en el arrecife de Playa Blanca, Pacífico colombiano

Regular sea-urchins are one of the main bioeroding organisms affecting coral reefs around the world. The abundance, distribution and bioerosion rate of the sea-urchin Centrostephanus coronatus, were determined in different reef zones of Playa Blanca fringing reef (Gorgona Island, Colombian pacific coast) during 1997 and 1998. The erosion rates were determined calcinating the gut content of the sea-urchins to eliminate all organic components and preserve the inorganic portion of calcium carbonate. C. coronatus showed the highest densities towards the central zones of the reef (plain-crest and front) (12.4 ind/m2; range 0-48 ind/m2). The highest mean bioerosion rate was 0.103 kgCaCO3/m2/yr in the reef plain-crest (0-0.69 kgCaCO3/m2/yr). In the other zones, (back reef and reef front) the mean bioerosion rates were 0.071 (range 0-0.39) and 0.052 (range 0-0.31) kgCaCO3/m2/yr respectively. According to the present data, it can be seen that the destruction of coralline skeletons, produced in this reef by sea-urchins is rather low, compared with the abrasion caused by these organisms in other places of the world. However, the combined action of C. coronatus and other bioeroding organisms (borers and grazers). along with some adverse environmental factors to corals, can be causing a negative balance between normal processes of reef accretion-destruction in Gorgona Island reefs.

Profile distribution of soil inorganic carbon along a chronosequence of grassland restoration on a 22-year scale in the Chinese Loess Plateau

Understanding the distribution of soil inorganic carbon (SIC) is meaningful and necessary for assessing soil carbon sequestration. However, changes in SIC following vegetation restoration are still not well studied in the Chinese Loess Plateau (CLP), which has undergone extensive changes from farmland to grassland. Here, we chose three study sites, farmland (FL), grassland restored for 12years (RG-1) and grassland restored for 22years (RG-2). The changes of SIC storage were determined under the conversion from a farmland ecosystem to extensively used grassland during the past twenty years. Results showed that the SIC content decreased with vegetation restoration, which averaged 18.5, 13.2 and 11.8gkg−1 in FL, RG-1 and RG-2, respectively. The SIC content was significantly lower in the top 80cm in RG-1 and RG-2 than in FL, but showed little variance at depths of 80–200cm among the study sites. It illustrated that the portion of carbonate was most likely released to the atmosphere as CO2 temporarily due to soil acidification and the increase of soil moisture in restored grassland. The lower δ13C value of SIC in RG-1 and RG-2 than in FL was most likely due to the soil carbonate exchanging with more soil respired CO2, with increasing vegetation coverage in restored grassland. Our results indicate that the SIC storage deceases in the restored grassland in situ probably due to the decrease of soil pH and the increase in soil water content. The SIC plays an important role when assessing the capacity of carbon sequestration with vegetation restoration in the semi-arid CLP.

Specificity of plant-microbe interactions in the tree mycorrhizosphere biome and consequences for soil C cycling.

Mycorrhizal associations are ubiquitous and form a substantial component of the microbial biomass in forest ecosystems and fluxes of C to these belowground organisms account for a substantial portion of carbon assimilated by forest vegetation. Climate change has been predicted to alter belowground plant-allocated C which may cause compositional shifts in soil microbial communities, and it has been hypothesized that this community change will influence C mitigation in forest ecosystems. Some 10,000 species of ectomycorrhizal fungi are currently recognized, some of which are host specific and will only associate with a single tree species, for example, Suillus grevillei with larch. Mycorrhizae are a strong sink for plant C, differences in mycorrhizal anatomy, particularly the presence and extent of emanating hyphae, can affect the amount of plant C allocated to these assemblages. Mycorrhizal morphology affects not only spatial distribution of C in forests, but also differences in the longevity of these diverse structures may have important consequences for C sequestration in soil. Mycorrhizal growth form has been used to group fungi into distinctive functional groups that vary qualitatively and spatially in their foraging and nutrient acquiring potential. Through new genomic techniques we are beginning to understand the mechanisms involved in the specificity and selection of ectomycorrhizal associations though much less is known about arbuscular mycorrhizal associations. In this review we examine evidence for tree species- mycorrhizal specificity, and the mechanisms involved (e.g., signal compounds). We also explore what is known about the effects of these associations and interactions with other soil organisms on the quality and quantity of C flow into the mycorrhizosphere (the area under the influence of mycorrhizal root tips), including spatial and seasonal variations. The enormity of the mycorrhizosphere biome in forests and its potential to sequester substantial C belowground highlights the vital importance of increasing our knowledge of the dynamics of the different mycorrhizal functional groups in diverse forests.

Soil geochemistry confines microbial abundances across an arctic landscape; implications for net carbon exchange with the atmosphere

A large portion of the World's terrestrial organic carbon is stored in Arctic permafrost soils. However, due to permafrost warming and increased in situ microbial mineralisation of released carbon, greenhouse gas releases from Arctic soils are increas- ing, including methane (CH4(g)). To identify environ- mental controls on such releases, we characterised soil geochemistry and microbial community conditions in 13 near-surface Arctic soils collected across Kongsf- jorden, Svalbard. Statistically significant correlations were found between proxies for carbonate mineral content (i.e. Ca and Mg) and soil pH (Spearman rho = 0.87, p 0.001). In turn, pH significantly inversely correlated with bacterial and Type I methanotroph gene abundances across the soils (r =- 0.71, p = 0.01 and r =- 0.74, p = 0.006, respectively), which also co-varied with soil phosphorous (P) level (r = 0.79, p = 0.01 and r = 0.63, p = 0.02, respec- tively). These results suggest that soil P supply, which is controlled by pH and other factors, significantly influences in situ microbial abundances in these Arctic soils. Overall, we conclude microbial responses to increasing 'old carbon' releases in this Arctic region are constrained by nutrient-deficiency in surface soils, with consequential impacts on the flux and composi- tion of carbon gasses released to the atmosphere.

Geochemical heterogeneity and reconstruction of the source of Upper Jurassic sandstone in the western part of West Siberia

The Shaim region located in the western part of the West Siberian Megabasin is the most wellstudied in this large and very important area. The crystalline basement is relatively shallow (1.5-2.2 km) there. A complex geological and geophysical study of this area was performed (1), and a geological map (1 : 200 000) of the preJurassic basement was compiled; a fragment of it is shown in Fig. 1. Two large structures are mapped there: the Danilov graben mostly composed of cenotypal basalt and rarely rhyolite of the Triassic age and the Shaim-Kusnetsov megaanticlinorium represented by a chain of Late Carboniferous-Early Permian monzodiorite-granosyenite massifs and their metamorphic schist frame (also known as a "granite-schist axis"). The preJurassic basement is overlain by the Upper Jurassic Vogulkinskaya Forma� tion mostly composed of sandstone. Within the Danilov graben, this formation is revealed by holes in the Tal'nikovaya, Symor'yakhskaya, Danilovskaya, and SeveroDanilovskaya areas, where it occurs on the Triassic rhyolite-basalt complexes. The same sedi� ments are observed on the territory of the "granite- schist axis" within the Tolumskaya, Teterevskaya, Mortym'yaTeterevskaya, and Trekhozernaya areas. In this study, we report a set of the chemical and geochemical analyses only from the Danilovskaya, Tal'nikovaya, Teterevskaya, and Trekhozernaya areas. The Vogulkinskaya Formation in the western part of West Siberia is mostly composed of sandstone (including glauconiterich), as well as gritstone, con� glomerate, rarely argillite, calcic sandstone, and orga� nogenic detrital limestone, which are almost not observed in other formations of the sedimentary cover in West Siberia (2). The thickness of the Vogulkinskaya Formation reaches 70 m. It is oilbearing and replaced by argillite of the Abalakskaya Formation. Sandstones from the Vogulkinskaya Formation are visually indistinguishable from each other; they have a lightgray up to brownish color and are almost always finegranular with a clay-carbonate cement. The mineralogy of sandstones of the Vogulkinskaya For� mation is considered for the area of the "granite- schist axis." They are composed of quartz and plagio� clase fragments; cement is clay-carbonate. Carbonate prevails, and its composition corresponds to calcite with admixtures of MgO (up to 1.07 wt %) and FeO (up to 0.79 wt %); sometimes the portion of carbonate reaches 50-60%, which allows us to attribute these rocks to sandy limestone. Glauconite, mica, plagio� clase, rutile, pyrite, and tourmaline are registered among the minor and accessory minerals. Quartz forms isometric grains with a size up to 1 mm. Albite is represented by tabular individuals with a size of 0. n mm. Mica often forms individual laths and aggregates, usually deformed. According to the composition, it corresponds to the muscovite-aluminoseladonite series (most analyses plot in the muscovite field) and contains up to 6% of the paragonite endmember. Tourmaline is characterized by individual wellformed prismatic grains with a size up to 0.5 mm; its chemical composition corresponds to that of dravite (48-50% of endmember) with a high concentration of foitite and magnesiofoitite (in total, up to 30-35%), olenite (up to 12%), and uvite (up to 10%). Rutile does not contain impurities and sometimes is replaced by titan� ite from the margins.

Effects of temperature on the physicochemical characteristics of fast pyrolysis bio-chars derived from Canadian waste biomass

Bio-chars are produced by means of a mobile pyrolysis unit from fast pyrolysis of different types of Canadian waste biomass including agricultural waste (wheat straw and flax straw), forest residue (sawdust) and animal manure (poultry litter). They were analyzed for their physicochemical changes with pyrolysis temperature (400–550°C). To study the chemical nature of bio-char samples, analyses such as XRD, FTIR, Raman spectroscopy, XPS, SEM, ICP, TGA and electrical conductivity measurements were performed. ICP-MS analysis showed that poultry litter-derived bio-char had the largest concentration of inorganic elements (∼200,000ppm) followed by wheat straw, flax straw and sawdust derived bio-chars. In addition, the alkaline elements were 4–14times that of essential elements (Fe and P) and 18–57times that of heavy elements. Electrical conductivity of bio-chars, a measure of their salinity, was maximum for all samples prepared at 400°C. SEM showed that sawdust derived bio-chars retained relatively less dissociated surfaces compared with other bio-chars. XRD confirmed the presence of sylvite, dolomite and quartz in the bio-chars. The deconvoluted XPS spectra indicated that for all precursors except poultry litter, aromatic/aliphatic carbon portion increased in the corresponding bio-char with the pyrolysis temperature. For all precursors, O/C mass ratio decreased with an increase in the pyrolysis temperature due to the development of compact aromatic structure in bio-char. This result was confirmed by a drastic increase in ID/IG (defect to graphitic carbon) ratio of bio-char samples produced at 550°C from the deconvolution results of Raman spectroscopy. Thermogravimetric analysis showed that biomass decomposition started at lower temperatures for the following order: poultry litter, wheat straw, flax straw and sawdust.

Herbivory makes major contributions to ecosystem carbon and nutrient cycling in tropical forests

The functional role of herbivores in tropical rainforests remains poorly understood. We quantified the magnitude of, and underlying controls on, carbon, nitrogen and phosphorus cycled by invertebrate herbivory along a 2800m elevational gradient in the tropical Andes spanning 12°C mean annual temperature. We find, firstly, that leaf area loss is greater at warmer sites with lower foliar phosphorus, and secondly, that the estimated herbivore-mediated flux of foliar nitrogen and phosphorus from plants to soil via leaf area loss is similar to, or greater than, other major sources of these nutrients in tropical forests. Finally, we estimate that herbivores consume a significant portion of plant carbon, potentially causing major shifts in the pattern of plant and soil carbon cycling. We conclude that future shifts in herbivore abundance and activity as a result of environmental change could have major impacts on soil fertility and ecosystem carbon sequestration in tropical forests.

English

Wind erosion effecting on soil carbon losses, should be considered from the standpoints of sustaining farmland productivity and producing accurate national carbon accounts.The worldwide spread of arid and semiarid areas with extensive damage to these areas gives them potential for carbon sequestration. Considering that a large portion of soil carbon is concentrated in 0 to 20 cm soil depth, carbon sequestration increases soil fertility,prevents erosion and improves the hydrological system. This paper introduces a case study in Dejgah catchment, Farashband County, Shiraz Province, Iran, which used to be a typical area with wind erosion and desertification in south western Iran. A field experiment was conducted in this region to investigate changes in soil carbon in relation to wind erosion. Samples were taken randomly from areas of up to 0.25 ha from each of the different wind erosion categories in June 2011. In each site 20 samples from surface layer (0 to 10 cm) and 20 samples from subsurface layer (10 to 20 cm) were collected, then samples from each layer were combined. Finally, two composite sample from each site and 24 composite soil samples were collected from surface layer (0 to 10 cm) and subsurface layer (10 to 20 cm) in 4 different wind erosion categories (light, moderate, high and severe). In the laboratory, each soil sample was thoroughly sieved to 2 mm to remove roots and incorporated litter and air-dried to determine soil physicochemical properties including pH, electrical conductivity, soil texture, bulk density, total nitrogen, and organic carbon content. Analysis results showed some soil properties largely influenced by the severity of wind erosion. In addition the results showed the impact of wind erosion on loss of carbon and nitrogen so that the organic C and N contents decreased significantly with wind erosion development. In addition changes in organic C content had a significant positive correlation with the soil fine particle content (clay) (Pb 0.01) and a significant negative correlation with sand content (Pb 0.01). Key words: Wind erosion, loss of soil organic carbon, carbon sequestration, global change.

Wildland fire emissions, carbon and climate: Characterizing wildland fuels

Smoke from biomass fires makes up a substantial portion of global greenhouse gas, aerosol, and black carbon (GHG/A/BC) emissions. Understanding how fuel characteristics and conditions affect fire occurrence and extent, combustion dynamics, and fuel consumption is critical for making accurate, reliable estimates of emissions production at local, regional, national, and global scales. The type, amount, characteristics, and condition of wildland fuels affect combustion and emissions during wildland and prescribed fires. Description of fuel elements has focused on those needed for fire spread and fire danger prediction. Knowledge of physical and chemical properties for a limited number of plant species exists. Fuel beds with potential for high impact on smoldering emissions are not described well. An assortment of systems, methods, analytical techniques, and technologies have been used and are being developed to describe, classify, and map wildland fuels for a variety of applications. Older systems do not contain the necessary information to describe realistically the wildland fuel complex. While new tools provide needed detail, cost effectiveness to produce a reliable national fuels inventory has not been demonstrated. Climate change-related effects on vegetation growth and fuel distribution may affect the amount of GHG/A/BC emissions from wildland fires. A fundamental understanding of the relationships between fuel characteristics, fuel conditions, fire occurrence, combustion dynamics, and GHG/A/BC emissions is needed to aid strategy development to mitigate the expected effects of climate change.

Filterable Redox Cycling Activity: A Comparison between Diesel Exhaust Particles and Secondary Organic Aerosol Constituents

The redox activity of diesel exhaust particles (DEP) collected from a light-duty diesel passenger car engine was examined using the dithiothreitol (DTT) assay. DEP was highly redox-active, causing DTT to decay at a rate of 23-61 pmol min(-1) μg(-1) of particle used in the assay, which was an order of magnitude higher than ambient coarse and fine particulate matter (PM) collected from downtown Toronto. Only 2-11% of the redox activity was in the water-soluble portion, while the remainder occurred at the black carbon surface. This is in contrast to redox-active secondary organic aerosol constituents, in which upward of 90% of the activity occurs in the water-soluble fraction. The redox activity of DEP is not extractable by moderately polar (methanol) and nonpolar (dichloromethane) organic solvents, and is hypothesized to arise from redox-active moieties contiguous with the black carbon portion of the particles. These measurements illustrate that "Filterable Redox Cycling Activity" may therefore be useful to distinguish black carbon-based oxidative capacity from water-soluble organic-based activity. The difference in chemical environment leading to redox activity highlights the need to further examine the relationship between activity in the DTT assay and toxicology measurements across particles of different origins and composition.

The significance of Chara vegetation in the precipitation of lacustrine calcium carbonate

AbstractA significant portion of calcium carbonate is deposited in lake sediments as a result of biological processes related to the photosynthetic activity of phytoplankton in the pelagic realm and, in addition, macrophytes in the littoral zone. Lake Wigry, one of the largest lakes in Poland (north‐east Poland), is characterized by: (i) carbonate sediments with a CaCO3 content exceeding 80% within the littoral zone; and (ii) large areas of submerged vegetation dominated by charophytes (macroscopic green algae, Characeae family). It is claimed that charophytes are highly effective in utilizing HCO3− and forming thick CaCO3 encrustations. Thus, this study was aimed at evaluating the CaCO3 production by dense Chara stands overgrowing the lake bottom reaching a depth of 4 m. In late July 2009, the fresh and dry mass of plants, the percentage contribution of calcium carbonate and the production of CaCO3 per 1 m2 were investigated along three transects at three depths (1 m, 2 m and 3 m, with each sample area equal to 0·0625 m2) per transect. The composition and structure of phytoplankton and the physico‐chemical properties of the water analysed in both the littoral and pelagic zones served as the environmental background and demonstrated moderately low fertility in the lake. The greatest dry plant mass exceeded 1000 g m−2 and CaCO3 encrustations constituted from 59% to over 76% of the charophyte dry weight. Thus, the maximum and average values of carbonates precipitated by charophytes were 685·5 and 438 g m−2, respectively, which exceeded previously reported results. A correlation of carbonate production with the depth of Chara stands was detected, and intermediate depths offered the most favourable conditions for carbonate precipitation (589 g m−2 on average). As precipitated carbonates are ultimately stored in bottom deposits, the results highlight the significance of charophytes in lacustrine CaCO3 sedimentation.

Effect of Alternate Metals for use in Natural Fibre Reinforced Fibre Metal Laminates under Bending, Impact and Axial Loadings

Fibre Metal Laminate (FML) is largely used in the manufacture of aircrafts. The commercially available FMLs, GLARE, CARALL (CArbon Reinforced ALuminium Laminate) and ARALL make use of Aluminium metal. Other FMLs that are under study by researchers make use of metals such as Titanium and Magnesium based alloys. Owing to the high cost of carbon fibre and the necessity for environment friendly alternatives, in the present work, a portion of carbon is replaced by natural fibre jute in CARALL and CARMAL (CArbon Reinforced MAgnesium Laminate). To the knowledge of the authors, this attempt has not been made before in the field of FMLs. The resulting CArbon-Jute Reinforced ALuminium Laminate and CArbon-Jute Reinforced MAgnesium Laminate are named as CAJRALL and CAJRMAL. Both these laminates are made by hand layup technique and then compressed in a compression moulding machine. The CAJRALL and the CAJRMAL specimens are subjected to Axial, Flexure and Impact tests according to ASTM standards. The effect of the orientations of fibres and influence of the stacking sequences of the fibre and metal combinations and the use of alternating metals on the mechanical performance, are experimentally investigated. The experimental and theoretical results as well as the results obtained through Finite Element Analysis are found to be in close agreement. Also the failure of the FML is predicted by conducting micro level structure analysis.

Global Molecular Analyses of Methane Metabolism in Methanotrophic Alphaproteobacterium, Methylosinus trichosporium OB3b. Part II. Metabolomics and 13C-Labeling Study

In this work we use metabolomics and 13C-labeling data to refine central metabolic pathways for methane utilization in Methylosinus trichosporium OB3b, a model alphaproteobacterial methanotrophic bacterium. We demonstrate here that similar to non-methane utilizing methylotrophic alphaproteobacteria the core metabolism of the microbe is represented by several tightly connected metabolic cycles, such as the serine pathway, the ethylmalonyl-CoA (EMC) pathway, and the citric acid (TCA) cycle. Both in silico estimations and stable isotope labeling experiments combined with single cell (NanoSIMS) and bulk biomass analyses indicate that a significantly larger portion of the cell carbon (over 60%) is derived from CO2 in this methanotroph. Our13 C-labeling studies revealed an unusual topology of the assimilatory network in which phosph(enol) pyruvate/pyruvate interconversions are key metabolic switches. A set of additional pathways for carbon fixation are identified and discussed.

ENERGY EFFICIENCY EVALUATION FOR A “GREEN” POWER GENERATION PROCESS WITH MINIMUM EFFORT ON CARBON DIOXIDE CAPTURE AND STORAGE

This study evaluates the use of cracking for the removal of carbon from fuels to be used in a power generation process. Unlike conventional power generation systems, the proposed system includes a cracking unit, the function of which is to convert primary fuels into H2 rich syngas and solid carbon, thus avoiding the emission of CO2 and the need for carbon capture and storage (CCS) in the power generation system. Based on the thermodynamic analysis of equilibrium reactions in the cracker, it is demonstrated that the operating temperature has a significant influence on the carbon capture rate achieved and the composition of the syngas. Carbon in the fuel can be captured in solid form from hydrocarbon fuels when operating the cracker at sufficiently high temperatures; however, only a portion of carbon can be captured in a solid form from oxygenated hydrocarbon fuels, with the maximum carbon capture rate being achieved at an optimum temperature. An energy analysis, which takes into account the energy penalty of CCS for the conventional power generation system, reveals that the net available energy from the proposed system is still not as high as that of the conventional system with CCS; however, the solid carbon can be of high commercial value when appropriate technology is employed to convert the carbon byproduct into a high-added-value carbon product such as carbon black or carbon nanotubes (CNTs).

Fern diversity and biomass at Chilapatta reserve forest of West Bengal Terai Duars in sub-humid tropical foothills of Indian eastern Himalayas

We documented the status of fern diversity, biomass and carbon accumulation at Chilapatta Reserve Forest in Cooch Behar Wildlife Division, West Bengal. Stratified random nested quadrat sampling was adopted for analyzing the qualitative and quantitative characters. Nineteen fern species were recorded, of which two are yet to be identified. Identified species were of eight families and nine genera. Highest and lowest frequency recorded were 25.44 and 0.19 while relative frequency varied from 3.16 to 12.25. Fern density ranged from 93 to 13,403 individuals ·ha−1. Most of the species were widely distributed. IVI values ranged from 7.54 to 37.45. The above ground portion of ferns accumulated the major portion of biomass and carbon.

Fosterville gold mine heated leach process

The Fosterville Gold mine is located approximately 20 km to the East of Bendigo in central Victoria. The gold at Fosterville occurs as solid solution within disseminated arsenopyrite and pyrite. The Fosterville ore bodies contain various amounts of native carbon in the form of bituminous coal. This carbon (non-carbonate carbon or NCC) has been the predominant mechanism for gold loss from the processing facility through ‘preg-robbing’. Processing of the Fosterville ore is achieved initially through crushing, grinding and flotation to extract the sulphides. The sulphide concentrate is oxidised using bacterial oxidation, before being leached in a conventional CIL circuit. A high portion of the native carbon (NCC) in the mine ore is naturally hydrophobic in nature, and subsequently reports to the flotation concentrate stream, and ultimately onto the CIL circuit. This NCC has a notable preg-robbing ability. Treatment of black shale ores, which have elevated NCC levels, has historically resulted in CIL recoveries as low as 35%, with around 60–80% of the gold loss from the leach circuit attributed to preg-robbing. Standard technologies for the dealing with a carbonaceous leach feed have been trialled with limited success. The discovery of the significance of heat on leach recoveries, triggered extensive testwork on a range of leach feed and tails samples. Pilot plant testing demonstrated that ‘heated leaching’ of the CIL tails was the best process with an average recovery increase of 7·5% being achieved. Following a successful pilot study, an engineering feasibility study was completed by Minerva Engineering, and the project economics determined. With strong recovery gains evident and a predicted project payback of 1–1·5 years, approval for the installation of the full scale plant was granted. Detailed design commenced in September 2008 with installation commencing in January 2009. The circuit was successfully commissioned in April 2009. Following commissioning, the heated leach circuit has achieved recovery gains of 4–14%, and has proven itself to be a significant contributor to the overall plant performance.

Concentrations, Loads, and Yields of Organic Carbon in Streams of Agricultural Watersheds

Carbon is cycled to and from large reservoirs in the atmosphere, on land, and in the ocean. Movement of organic carbon from the terrestrial reservoir to the ocean plays an important role in the global cycling of carbon. The transition from natural to agricultural vegetation can change the storage and movement of organic carbon in and from a watershed. Samples were collected from 13 streams located in hydrologically and agriculturally diverse watersheds, to better understand the variability in the concentrations and loads of dissolved organic carbon (DOC) and particulate organic carbon (POC) in the streams, and the variability in watershed yields. The overall annual median concentrations of DOC and POC were 4.9 (range: 2.1-6.8) and 1.1 (range: 0.4-3.8) mg C L, respectively. The mean DOC watershed yield (± SE) was 25 ± 6.8 kg C ha yr. The yields of DOC from these agricultural watersheds were not substantially different than the DOC yield from naturally vegetated watersheds in equivalent biomes, but were at the low end of the range for most biomes. Total organic carbon (DOC + POC) annually exported from the agricultural watersheds was found to average 0.03% of the organic carbon that is contained in the labile plant matter and top 1 m of soil in the watershed. Since the total organic carbon exported from agricultural watersheds is a relatively small portion of the sequestered carbon within the watershed, there is the great potential to store additional carbon in plants and soils of the watershed, offsetting some anthropogenic CO emissions.

The role of harvest residue in rotation cycle carbon balance in loblolly pine plantations. Respiration partitioning approach.

Timber harvests remove a significant portion of ecosystem carbon. While some of the wood products moved off-site may last past the harvest cycle of the particular forest crop, the effect of the episodic disturbances on long-term on-site carbon sequestration is unclear. The current study presents a 25year carbon budget estimate for a typical commercial loblolly pine plantation in North Carolina, USA, spanning the entire rotation cycle. We use a chronosequence approach, based on 5years of data from two adjacent loblolly pine plantations. We found that while the ecosystem is very productive (GEP up to 2900gm-2 yr-1 , NEE at maturity about 900g Cm-2 yr-1 ), the production of detritus does not offset the loss of soil C through heterotrophic respiration (RH ) on an annual basis. The input of dead roots at harvest may offset the losses, but there remain significant uncertainties about both the size and decomposition dynamics of this pool. The pulse of detritus produced at harvest resulted in a more than 60% increase in RH . Contrary to expectations, the peak of RH in relation to soil respiration (SR) did not occur immediately after the harvest disturbance, but in years3 and 4, suggesting that a pool of roots may have remained alive for the first few years. On the other hand, the pulse of aboveground RH from coarse woody debris lasted only 2years. The postharvest increase in RH was offset by a decrease in autotrophic respiration such that the total ecosystem respiration changed little. The observed flux rates show that even though the soil C pool may not necessarily decrease in the long-term, old soil C is definitely an active component in the site C cycle, contributing about 25-30% of the RH over the rotation cycle.

Preface &amp;quot;Sources and rapid biogeochemical transformation of dissolved organic matter in the Atlantic surface ocean&amp;quot;

One of the most important issues needed to be studied to better understand global fluxes of marine organic matter is to resolve its molecular characteristics and mechanisms which convert fresh, labile biomolecules into semi-labile and refractory dissolved organic compounds (Jiao et al., 2010) which resist degradation for an average time of 5000 years (Bauer et al., 1992; Williams and Druffel, 1987). From a chemical point of view, the persistence of marine dissolved organic matter (DOM) is very unusual. The mostly oxygenand nutrient-rich oceanic water column should be conducive to a rapid microbial degradation of organic matter and subsequent release of CO2. Contrary to this expectation, however, a significant portion of the atmospheric carbon remains in the DOM of the oceans and circulates in global currents on long time scales. Despite the importance of gaining better insights into the molecular mechanisms affecting organic carbon dynamics, very little is known about these processes. Thus, recent reports from the intergovernmental panel on climate change (Denman et al., 2007) barely considered potential changes in quality, quantity and fluxes of marine organic matter. In the oceans, dissolved organic substances constitute an important source of organic carbon and organic nitrogen (Hansell et al., 2009). The pool of dissolved organic carbon (DOC) exceeds the amount of carbon stored in marine animals, plants and bacteria by a factor of about 200. The majority of DOM in the oceans is originally formed from CO2 by plankton and land plants during photosynthesis. The DOM, resulting from this organic material, is directly released into the water by marine plankton and during the degradation of these organisms. Also, DOM can be transported into the oceans via rivers and atmospheric deposits via aerosols. A small fraction of marine DOM, such as persistent organic pollutants or black carbon derivatives, can be derived from anthropogenic activities. DOM can bind to trace metals such as iron and is therefore also responsible for their distribution in the sea. The complex composition of DOM is an enormous analytical challenge, resulting in sparse information on chemical structures. The DOM complexity prevents resolution of single molecules by chromatographic separation or conventional mass spectrometry. However, within the last 10 years analytical instruments, which can deliver molecular signals, improved tremendously. Namely, improvements of nuclear magnetic resonance spectroscopy (NMR) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) opened a new analytical window for the molecular characterization of natural organic matter (e.g. Stenson et al., 2003; Kujawinski et al., 2004; Koch et al., 2005; Hertkorn et al., 2008; Witt et al., 2009). Meridional transits of polar research vessels offer a great opportunity to perform long-distance surface water transects with continuous water and air sampling, since frequent stops for long station work are usually not possible during such transit cruises. Trace metal (Pohl et al., 2011; Helmers, 1996) and plankton studies (Robinson et al., 2009) and a recent GEOTRACES pilot study in the Atlantic Ocean (Rutgers van der Loeff, 2007) are great examples for the importance of such projects. Previous work along the north–south transect also provided a high resolution comparison of bacterial and primary production (Hoppe et al., 2002). The authors suggested that the observed net heterotrophy required