生物能源对饲料市场及相关产业的影响及对策研究

<正>随着石化能源的价格上涨及其所带来的环境问题,生物能源作为一种可再生能源越来越受到重视,其中燃料乙醇和生物柴油尤其被看好。目前,燃料乙醇的原料以玉米为主,生物柴油的原料以大豆和菜籽     

Use of fallout Cs in investigations of overbank sediment deposition on river floodplains

River floodplains have been recognised as important sinks for storing suspended sediment and associated contaminants mobilised from the upstream catchment. However, information on contemporary rates of overbank sedimentation is difficult to obtain using conventional methods. Measurements of the ¹³⁷Cs content of floodplain sediments provide an alternative approach to obtaining; estimates of medium-term rates (ca. 40 years) of overbank sediment deposition. The ¹³⁷Cs approach requires only a single site visit and minimum sample preparation. Furthermore, it is capable of providing information on spatial patterns of sediment deposition on floodplains, which is needed to improve our understanding of the processes involved in overbank flow and sediment deposition. This paper reviews the basis for using ¹³⁷Cs measurements in floodplain sedimentation studies and presents improved procedures for interpreting ¹³⁷Cs profiles in floodplain sediments and for obtaining estimates of sedimentation rates from single measurements of the total. ¹³⁷Cs inventories of bulk sediment cores. The results obtained from a case study undertaken on the floodplain of the River Stour, Dorset, UK, are presented.     

Analysis of anthocyanins in rat intestinal contents--impact of anthocyanin chemical structure on fecal excretion

Absorption of dietary anthocyanins is limited; however, fecal anthocyanin excretion has been rarely studied. We developed a method for extraction and analysis of fecal anthocyanins. Aqueous methanol (60%) maximized extraction efficiency (approximately 88%). Severe anthocyanin degradation (monitored by high-performance liquid chromatography) was observed in feces stored at -18 degrees C; therefore, storage time should be minimized and lower temperatures used. Fecal and cecal content samples were collected from 32 rats receiving either chokeberry, bilberry, grape-enriched (3.85 g monomeric anthocyanin per kg diet), or control diet for 14 weeks. Fecal anthocyanin concentrations were significantly different among groups (0.7/1.8/2.0 g/kg wet feces, chokeberry/bilberry/grape). Anthocyanin profiles of cecal contents and feces were similar. Losses in the intestinal contents were high for anthocyanin glucosides, moderate for galactosides, and negligible for arabinosides or xylosides. Acylation or diglucosylation enhanced anthocyanin stability. High anthocyanin concentration in the fecal content may favor anthocyanin absorption into the colon epithelial cells, resulting in potential health benefits.     

An aggregation index (AI) to quantify spatial patterns of landscapes

There is often need to measure aggregation levels of spatial patterns within a single map class in landscape ecological studies. The contagion index (CI), shape index (SI), and probability of adjacency of the same class (Qi), all have certain limits when measuring aggregation of spatial patterns. We have developed an aggregation index (AI) that is class specific and independent of landscape composition. AI assumes that a class with the highest level of aggregation (AI =1) is comprised of pixels sharing the most possible edges. A class whose pixels share no edges (completely disaggregated) has the lowest level of aggregation (AI =0). AI is similar to SI and Qi, but it calculates aggregation more precisely than the latter two. We have evaluated the performance of AI under varied levels of (1) aggregation, (2) number of patches, (3) spatial resolutions, and (4) real species distribution maps at various spatial scales. AI was able to produce reasonable results under all these circumstances. Since it is class specific, it is more precise than CI, which measures overall landscape aggregation. Thus, AI provides a quantitative basis to correlate the spatial pattern of a class with a specific process. Since AI is a ratio variable, map units do not affect the calculation. It can be compared between classes from the same or different landscapes, or even the same classes from the same landscape under different resolutions.     

Biomass production,nutrient cycling and distribution in age-sequence Chinese fir (<Emphasis Type="Italic">Cunninghamia lanceolate</Emphasis>) plantations in subtropical China

Biomass production and nutrient (N, P, K, Ca and Mg) accumulation, distribution and cycling were quantified in young, mature and over-mature (10-, 22-, and 34-year old) Chinese fir [Cunninghamia lanceolate (Lamb.) Hook] plantations in southern China. Total stand biomass of young, mature and over-mature stands was 38, 104 and 138 t ha^?1 respectively. Biomass production increased significantly with age. Stem wood represented the highest percentage of stand biomass, accounting for 41, 55 and 63 % in the young, mature and over-mature plantations respectively. Nutrients concentration was highest in live needles and branches, and lowest in stem wood. The plantations accumulated more N, followed by K, Ca, Mg, and P. Nutrient return amount, nutrient utilization efficiency, nutrient turnover time, the ratio of nutrient return and uptake increased with stand age, which implies that young Chinese fir deplete soil nutrients to maintain growth, and efficiently utilize nutrients to decrease dependence on soil nutrients as they age. Harvesting young Chinese fir plantations would therefore lead to high nutrient loss, but prolonging the rotation length could improve soil recovery, and help sustain productivity in the long-term. Improved nutrient return through litterfall as stands get older may also be beneficial to nutrient pool recovery.