Environmental Impacts of Landfill Bioreactorcells in Comparison to Former Landfill Techniques

Former and present landfill techniques at the Filbornaplant in Helsingborg, South Sweden are compared withrespect to impacts on the environment. This includes thepotential for nutrient recovery and heavy metalimmobilisation in the waste residue. The results showthat optimised landfill bioreactor-cells have a higherturn-over rate for organic matter compared to the formerlandfills, whereas the retention capacity for heavymetals in both systems was surprisingly high. Full scaleleachate data, as well as a laboratory leachingexperiments confirmed the role of bioreactor cells asanaerobic filters enabling a separation of nutrients froma mixed waste, while the toxic metals are retained. Theconclusion of this article is that by simple measures, thebiological processes can be optimised, resulting inhigher turn-over rates for organic matter and thusaccelerated waste stabilisation.     

Influence of catchment characteristics,forestry activities and deposition on nitrogen export from small forested catchments

The ability to predict nitrogen export from forested catchments is essential in order to evaluate the effects of anthropogenic activities on the trophic status of lakes and sea areas, and to extrapolate the results to catchments from which no measurements are available. Data from 20 forested catchments (0.3–42 km²) in Finland and Sweden during the 10-year period 1979–88 were used to develop empirical multivariate regression models of average NO₃-N, NH₄-N and organic N export fluxes as a function of geomorphological, meteorological, hydrological, deposition and forest management variables. A combination of high inorganic N deposition or air temperature and a low extent of organic soils was related to (R² = 0.64) high losses of NO₃-N. A strong correlation between N deposition and air temperature makes it difficult to distinguish the effects of one variable from the other. Retention of deposited nitrogen is still high in most of the catchments. High losses of NH₄-N had the strongest correlation with forestry activities and stream density. A combination of drainage percentage and temperature was related to (R² = 0.53) losses of NH₄-N. The most important factors explaining spatial variability of organic N losses were clearly forestry activities. A combination of high percentage of drainage and clear-cutting was related to (R² = 0.81) high organic N losses. However, within the catchments, large-scale forest management practices were needed before any clear effect on spatial variability was detected. All the equations obtained were influenced by the choice of a limited number of catchments. No causal relationships between losses and the explaining variables can be inferred from this type of study.     

Characterization of potato leaf starch

The starch accumulation-degradation process as well as the structure of leaf starch are not completely understood. To study this, starch was isolated from potato leaves collected in the early morning and late afternoon in July and August, representing different starch accumulation rates. The starch content of potato leaves varied between 2.9 and 12.9% (dry matter basis) over the night and day in the middle of July and between 0.6 and 1.5% in August. Scanning electron microscopy analyses of the four isolated starch samples showed that the granules had either an oval or a round shape and did not exceed 5 microm in size. Starch was extracted by successive washing steps with dimethyl sulfoxide and precipitated with ethanol. An elution profile on Sepharose CL-6B of debranched starch showed the presence of a material with a chain length distribution between that generally found for amylose and amylopectin. Amylopectin unit chains of low molecular size were present in a higher amount in the afternoon than in the morning samples. What remains at the end of the night is depleted in specific chain lengths, mainly between DP 15 and 24 and above DP 35, relative to the end of the day.     

Catalytic effect of various metal ions on the methylation of mercury in the presence of humic substances

Methylation of Hg²⁺ (Hg(NO₃)₂) in the presence of fulvic acid (FA) and various metal ions has been studied. The concentrations of Hg²⁺ and FA ranged from 5 to 20 mg L^?1 and 171 to 285 mg L^?1 DOC, respectively. The pH range was 3 to 6.5. FA was isolated from an acid brown-water lake by XAD-8 polymeric adsorbent. Methylmercury production in the dark during 2 to 4 days incubation at 30 °C increased with increasing concentrations of Hg²⁺ ion and FA as well as with additions of metal ions (5 to 10 × 10^?5 mole L^?1 The observed catalytic activity of metal ions followed the order Fe³⁺ (Fe²⁺) > Cu²⁺ ≈ Mn²⁺, > Al³⁺. The production of methylmercury had a pH-optimum around 4 to 4.5 at the conditions tested.     

Reexamination of the Three-Dimensional Structure of the Small Subunit of RuBisCo from Higher Plants

The structure of L(8)S(8) RuBisCo (where L is the large subunit and S is the small subunit) from spinach has been determined to a resolution of 2.8 ?ngstrom by using fourfold averaging of an isomorphous electron density map based on three heavy-atom derivatives. The structure of the S subunit is different from that previously reported for the tobacco S subunit in spite of 75 percent sequence identity. The elements of secondary structure, four antiparallel beta strands and two alpha helices, are the same, but the topology and direction of the polypeptide chain through these elements differ completely. One of these models is clearly wrong. The spinach model has hydrophobic residues in the core between the alpha helices and beta sheet as well as conserved residues in the subunit interactions. The deletion of residues 49 to 62 that is present in the Anabaena sequence removes a loop region in the spinach model. The positions of three mercury atoms in the heavy-atom derivatives agree with the assignment of side chains in the spinach structure.     

Interactive effects of drought and edge exposure on old-growth forest understory species

Landscape Ecology - Both climatic extremes and land-use change constitute severe threats to biodiversity, but their interactive effects remain poorly understood. In forest ecosystems, the effects...     

Solar wind-induced atmospheric erosion at Mars: first results from ASPERA-3 on Mars Express

The Analyzer of Space Plasma and Energetic Atoms (ASPERA) on board the Mars Express spacecraft found that solar wind plasma and accelerated ionospheric ions may be observed all the way down to the Mars Express pericenter of 270 kilometers above the dayside planetary surface. This is very deep in the ionosphere, implying direct exposure of the martian topside atmosphere to solar wind plasma forcing. The low-altitude penetration of solar wind plasma and the energization of ionospheric plasma may be due to solar wind irregularities or perturbations, to magnetic anomalies at Mars, or both.     

A mutation in PRKAG3 associated with excess glycogen content in pig skeletal muscle

A high proportion of purebred Hampshire pigs carries the dominant RN- mutation, which causes high glycogen content in skeletal muscle. The mutation has beneficial effects on meat content but detrimental effects on processing yield. Here, it is shown that the mutation is a nonconservative substitution (R200Q) in the PRKAG3 gene, which encodes a muscle-specific isoform of the regulatory gamma subunit of adenosine monophosphate-activated protein kinase (AMPK). Loss-of-function mutations in the homologous gene in yeast (SNF4) cause defects in glucose metabolism, including glycogen storage. Further analysis of the PRKAG3 signaling pathway may provide insights into muscle physiology as well as the pathogenesis of noninsulin-dependent diabetes mellitus in humans, a metabolic disorder associated with impaired glycogen synthesis.     

The effect of dietary fiber from wheat processing streams on the formation of carboxylic acids and microbiota in the hindgut of rats

Colonic fermentation of dietary fiber produces carboxylic acids and may stimulate the growth of beneficial bacteria. This study investigated how byproducts of wheat processing (distillers' grains and two fractions from the wet fractionation to starch and gluten, one of which was treated with xylanase) affect the composition of the cecal microbiota and the formation of carboxylic acids in rats. Differences were mostly found between diets based on supernatants and pellets, rather than between fiber sources. Cecal pools and levels of most carboxylic acids in portal blood were higher for rats fed the supernatant diets, while cecal pH and ratios of acetic to propionic acid in portal blood were lower. The diet based on supernatant from distillers' grains gave the highest level of bifidobacteria. Molecular weight and solubility are easier to modify with technological processes, which provides an opportunity to optimize these properties in the development of health products.