常温上流式厌氧污泥床反应器处理V_(B12)、淀粉混合废水的研究

常温(20～25℃)条件下,采用上流式厌氧污泥床(UASB)反应器处理维生素B_(12)、淀粉混合废水,当进水COD_(cr)浓度为8200～8900mg/L时,容积负荷可达到9.6kg/m~3d;COD_(cr)去除率为83.2％;产气率为0.436m~3/kgCOD_(cr)(去除)。     

Simulating sensitivities of Changbai Mountain forests to potential climate change

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How Climate and Vegetation Influence the fire Regime of the Alaskan Boreal Biome: The Holocene Perspective

We synthesize recent results from lake-sediment studies of Holocene fire-climate-vegetation interactions in Alaskan boreal ecosystems. At the millennial time scale, the most robust feature of these records is an increase in fire occurrence with the establishment of boreal forests dominated by Picea mariana: estimated mean fire-return intervals decreased from ≥300 yrs to as low as ∼80 yrs. This fire-vegetation relationship occurred at all sites in interior Alaska with charcoal-based fire reconstructions, regardless of the specific time of P. mariana arrival during the Holocene. The establishment of P. mariana forests was associated with a regional climatic trend toward cooler/wetter conditions. Because such climatic change should not directly enhance fire occurrence, the increase in fire frequency most likely reflects the influence of highly flammable P. mariana forests, which are more conducive to fire ignition and spread than the preceding vegetation types (tundra, and woodlands/forests dominated by Populus or Picea glauca). Increased lightning associated with altered atmospheric circulation may have also played a role in certain areas where fire frequency increased around 4000 calibrated years before present (BP) without an apparent increase in the abundance of P. mariana. When viewed together, the paleo-fire records reveal that fire histories differed among sites in the same modern fire regime and that the fire regime and plant community similar to those of today became established at different times. Thus the spatial array of regional fire regimes was non-static through the Holocene. However, the patterns and causes of the spatial variation remain largely unknown. Advancing our understanding of climate-fire-vegetation interactions in the Alaskan boreal biome will require a network of charcoal records across various ecoregions, quantitative paleoclimate reconstructions, and improved knowledge of how sedimentary charcoal records fire events. In this paper, charcoal refers to macroscopic (≥180 μm) as opposed to microscopic (< 180 μm) particles unless indicated otherwise. Radiocarbon ages were converted to calibrated years before AD 1950 using the atmospheric calibration data set (Stuiver et al. 1998).     

Studies on the enzymatic and fungal degradation of cross-linked gelatin and its graft copolymers

Glutaraldehyde cross-linked gelatin was graft copolymerized with acrylic acid, acrylamide, vinyl acetate, methyl acrylate, and methyl methacrylate either individually or in combination. The enzymatic and fungal degradation of these graft copolymers with trypsin, pepsin, and mixed cultures ofAspergillus niger, Penicillium ochrochloron, Penicillium funiculosum, andTrichoderma viride was studied for short and extended periods. The weight loss suffered by the samples, the weight of biomass formed, the nitrogen content, and the pH of the culture medium were determined. With the help of these data, the extent of utilization of graft copolymers by fungi as a sole source of carbon was estimated. The samples with less than 100% grafting and with a ratio of polymethyl methacrylate content (L) to polyacrylic acid (H) content (L/H values) lower than 1.0 were readily and extensively degraded.IICT Communication No. 3375.     

Spatial analysis of habitat selection by Sitka black-tailed deer in Southeast Alaska,USA

We used a vector-based geographic information system (GIS) to examine habitat selection by radiocollared Sitka black-tailed deer (Odocoileus hemionus sitkensis) in logged forests of southeast Alaska. Our main objective was to explain deer habitat selection relative to old-growth/clear-cut edges and edge habitats at two different spatial scales. Deer home ranges contained higher percentages of recent clear-cuts (50–69%) than the study area (37%;P<0.01) and had higher old-growth/clear-cut edge densities than expected by chance (P<0.01). Deer relocation points were closer to old-growth/clear-cut edges (average=135 m) than random points located within each deer's relocation area (average=168 m;P=0.05). Likewise, deer relocations were closer to old-growth/clear-cut edges than points randomly located within old-growth stands or recent clear-cuts (P<0.01). As the size of clear-cuts increased, both deer relocation density and the proportion of a clear-cut occupied by deer home ranges decreased. Because old growth is important deer habitat and clear-cuts can produce deer forage for only 20–30 years after logging in southeast Alaska, deer management plans such as preserving entire watersheds and maintaining mixes of old growth and recent clear-cut have been proposed. Our data suggest that deer need a diversity of habitats near each other within their home ranges.     

EVALUATION OF STORMSEWER CONTROL ALGORITHMS USING A TRANSIENT MIXED FLOW MODEL1

ABSTRACT: a hydraulic transient model that is capable of simultaneously modeling open channel and pressurized flows is used to study active control of a deep tunnel stormwater collection system. The simultaneous occurrence of open channel flow and pressurized flow is termed mixed flow. This paper demonstrates the application of a mixed flow hydraulic model to the development of an active control scheme. It is shown that dynamic conditions can exist in a storm sewer system even under moderate inflow conditions and that these conditions, particularly at the time of full system pressurization, can influence the operation of the dynamic control, so that accurate hydraulic modeling is essential to proper control formulation.     

SPATIALLY OPTIMIZING FOREST MANAGEMENT SCHEDULES TO MEET STORMFLOW CONSTRAINTS1

ABSTRACT: A spatial optimization model is developed and used to limit cumulative effects resulting from storm events by strategically arranging and scheduling forest treatments to meet peak storm-flow constraints. A mixed integer forest management scheduling formulation is used to select the location and timing of forest treatments. The approach includes simulated spatial routing of storm-flows imbedded as hydrologic process constraints (in a nested schedule) within longer-term forest management planning periods in the mathematical programming model. Although difficult to solve, the model shows promise for further research.     

Syntaxonomy of Southern Ural Forests as a basis for the system of their protection

Using the example of Southern Ural forests, it is shown that the Braun-Blanquet method is promising for estimating the efficiency of the system of specially protected natural areas (SPNAs) and drawing up guidelines for its further development. In particular, evidence is provided that forests of the unions Aconito-Piceion and Lathyro-Quercion are protected quite insufficiently. Proposals concerning organization of new SPNAs are formulated.