Capacity of biochar application to maintain energy crop productivity: soil chemistry, sorghum growth, and runoff water quality effects

Pyrolysis of crop biomass generates a by-product, biochar, which can be recycled to sustain nutrient and organic C concentrations in biomass production fields. We evaluated effects of biochar rate and application method on soil properties, nutrient balance, biomass production, and water quality. Three replications of eight sorghum [ (L.) Moench] treatments were installed in box lysimeters under greenhouse conditions. Treatments comprised increasing rates (0, 1.5, and 3.0 Mg ha) of topdressed or incorporated biochar supplemented with N fertilizer or N, P, and K fertilizer. Simulated rain was applied at 21 and 34 d after planting, and mass runoff loss of N, P, and K was measured. A mass balance of total N, P, and K was performed after 45 d. Returning 3.0 Mg ha of biochar did not affect sorghum biomass, soil total, or Mehlich-3-extractable nutrients compared to control soil. Yet, biochar contributed to increased concentration of dissolved reactive phosphorus (DRP) and mass loss of total phosphorus (TP) in simulated runoff, especially if topdressed. It was estimated that up to 20% of TP in topdressed biochar was lost in surface runoff after two rain events. Poor recovery of nutrients during pyrolysis and excessive runoff loss of nutrients for topdressed biochar, especially K, resulted in negative nutrient balances. Efforts to conserve nutrients during pyrolysis and incorporation of biochar at rates derived from annual biomass yields will be necessary for biochar use in sustainable energy crop production.     

Ecology and Conservation of the Endangered American Burying Beetle (Nicrophorus americanus)

Field studies were conducted on the western population of the endangered American burying beetle (Nicrophorus americanus) in Oklahoma and Arkansas to determine its habitat affinities. A common cause of declining populations is some specialized adaptation that makes it difficult to respond to a rapidly changing habitat. We evaluated the hypothesis that N. americanus is a habitat specialist in its search for food, preferring mature forests with deep, humic soils. This hypothesis was rejected. Based on comparisons of niche breadth among syntopic congeners and niche overlap, N. americanus is relatively generalized in its use of a range of habitats when searching for food. It is likely that the generalist nature and the endangered status of N. americanus both derive from the fact that it is the largest member of its guild. In comparison to smaller species, N. americanus breeds on larger carcasses, which are more unpredictable in space and time. It is likely, therefore, that N. americanus must search over a larger area and greater diversity of habitats than its smaller congeners.     

Surface measurements of global warming causing atmospheric constituents in Korea

The expansion of the industrial economy and the increase of population in Northeast Asian countries have caused much interestin climate monitoring related to global warming. However, new techniques and better platforms for the measurement of globalwarming and regional databases are still old-fashioned and arenot being developed sufficiently. With respect to this agenda,since 1993, at the request of the World Meteorological Organization (WMO), to monitor functions of global warming, theKorea Meteorological Administration (KMA) has set up a Global Atmospheric Watch (GAW) Station on the western coast of Korea(Anmyun-do) and has been actively monitoring global warming overNortheast Asia. In addition, atmospheric carbon dioxide (CO₂) has been measured for a similar KMA global warmingprogram at Kosan, Cheju Island since 1990. Aerosol and radiationhave also been measured at both sites as well as in Seoul. Theobservations have been analyzed using diagnostics of climate change in Northeast Asia and also have been internationally compared. Results indicate that greenhouse gases are in good statistic agreement with the NOAA/Climate Monitoring and Diagnostics Laboratory (CMDL) long-term trends of monthly meanconcentrations and seasonal cycles. Atmospheric particulatematter has also been analyzed for particular Asian types interms of optical depth, number concentration and size distribution.     

Relationship Between Bird Abundances and Landscape Characteristics: The Influence of Scale

Scale is important to consider when investigating effects of the environment on a species. Breeding Bird Survey (BBS) data and landscape metrics derived from aerial photographs were evaluated to determine how relationships of bird abundances with landscape variables changed over a continuous range of 16 spatial scales. We analyzed the average number of birds per stop (1985–1994) for five songbird species (family Cardinalidae) for each of 50 stops on 198 BBS transects throughout six states in the Central Plains, USA. Land along each transect was categorized into six cover types, and landscape metrics of fractal dimension (a measure of shape complexity of habitat patches), edge density, patch density, and percent area were calculated, with principal components used to construct composite environmental variables. Associations of bird abundances and landscape variables changed in accordance with small scale changes. Abundances of three species were correlated with edge density and one with component I, which subsumes initial variables of patch density for urban, closed forest, open forest, and open country. Fractal dimension and component II (summarizing amount of closed forest versus open country) were associated with the most species. Correlation patterns of fractal dimension with northern cardinal (Cardinalis cardinalis) and painted bunting (Passerina ciris) abundances were similar, with highest correlations at intermediate to small scales, suggesting indirectly that these species thrive in areas where local habitat conditions are most important. Multiscale analysis can provide insight into the spatial scale(s) at which species respond, a topic of intrinsic scientific interest with applied implications for researchers establishing protocols to assess and monitor avian populations.     

Oxy-fuel coal combustion—A review of the current state-of-the-art

Carbon dioxide emissions will continue being a major environmental concern due to the fact that coal will remain a major fossil-fuel energy resource for the next few decades. To meet future targets for the reduction of greenhouse gas (GHG) emissions, capture and storage of CO₂ is required. Carbon capture and storage technologies that are currently the focus of research centres and industry include: pre-combustion capture, post-combustion capture, and oxy-fuel combustion. This review deals with the oxy-fuel coal combustion process, primarily focusing on pulverised coal (PC) combustion, and its related research and development topics. In addition, research results related to oxy-fuel combustion in a circulating fluidised bed (CFB) will be briefly dealt with.During oxy-fuel combustion, a combination of oxygen, with a purity of more than 95 vol.%, and recycled flue gas (RFG) referred to as oxidant is used for combusting the fuel producing a gas consisting of mainly CO₂ and water vapour, which after purification and compression, is ready for storage. The high oxygen demand is supplied by a cryogenic air separation process, which is the only commercially available mature technology. The separation of oxygen from air as well as the purification and liquefaction of the CO₂-enriched flue gas consumes significant auxiliary power. Therefore, the overall net efficiency is expected to be decreased by 8–12% points, corresponding to a 21–35% increase in fuel consumption. Alternatively, ion transport membranes (ITMs) are proposed for oxygen separation, which might be more energy efficient. However, since ITMs are far away from becoming a mature technology, it is widely expected that cryogenic air separation will be the selected technology in the near future. Oxygen combustion is associated with higher temperatures compared with conventional air combustion. Both fuel properties as well as limitations of steam and metal temperatures of the various heat exchanger sections of the boiler require a moderation of the temperatures in the combustion zone and in the heat-transfer sections. This moderation in temperature is accomplished by means of recycled flue gas. The interdependencies between the fuel properties, the amount and temperature of the recycled flue gas, and the resulting oxygen concentration in the combustion atmosphere are reviewed.The different gas atmosphere resulting from oxy-fuel combustion gives rise to various questions related to firing, in particular, with respect to the combustion mechanism, pollutant reduction, the risk of corrosion, and the properties of the fly ash or its resulting deposits. In this review, detailed nitrogen and sulphur chemistry was investigated in a laboratory-scale facility under oxy-fuel combustion conditions. Oxidant staging succeeded in reducing NO formation with effectiveness comparable to that typically observed in conventional air combustion. With regard to sulphur, a considerable increase in the SO₂ concentration was measured, as expected. However, the H₂S concentration in the combustion atmosphere in the near-flame zone increased as well. Further results were obtained in a pilot-scale test facility, whereby acid dew points were measured and deposition probes were exposed to the combustion environment. Slagging, fouling and corrosion issues have so far been addressed via short-term exposure and require further investigation.Modelling of PC combustion processes by computational fluid dynamics (CFD) has become state-of-the-art for conventional air combustion. Nevertheless, the application of these models for oxy-fuel combustion conditions needs adaptation since the combustion chemistry and radiative heat transfer is altered due to the different combustion gas atmosphere.CFB technology can be considered mature for conventional air combustion. In addition to its inherent advantages like good environmental performance and fuel flexibility, it offers the possibility of additional heat exchanger arrangements in the solid recirculation system, i.e. the ability to control combustion temperatures despite relatively low flue gas recycle ratios even when combusting in the presence of high oxygen concentrations.