当代大学生思想变化规律的研究——基于蚌埠学院部分学生的问卷调查与访谈

对当代大学生进行思想政治理论教育，必须深入研究当代大学生的思想变化规律。研究表明，当代大学生的思想变化呈现出如下规律：马克思主义为主流信仰，信仰比例随年级升高呈“V”形分布；政治认同感强，政治关注度与自身利益紧密相关；人生态度积极乐观，注意自我价值的实现；反对非诚信行为，期待诚信的社会环境。对以上规律的研究，有助于更有效地对当代大学生开展社会主义核心价值观教育。     

基于SWAT模型的大安市降水入渗量变化的模拟研究

针对近年的研究热点,通过SWAT模型对半干旱、盐碱化严重的吉林省大安市进行降水入渗模拟。以2000、2004和2008年遥感影像解译得到的土地利用数据为基础,结合SWAT模型的模拟结果,讨论LUCC与降水入渗量的相关关系。2008年与2000年相比,难利用地的面积有所降低,旱地、草地等发生了大面积的增加,研究区内土地状况有所好转。通过SWAT模型运行得到的结果显示:2008年的平均降水入渗量为56.27 mm,比2000年的值高。利用降水入渗系数法进行计算,也得到了2008年的降水入渗量高于2000年的结果,这与SWAT模型模拟得到的结果有着相同的趋势,且平均降水入渗量的标准偏差为5.27,说明SWAT模型对于研究区有良好的适应性。同时,根据土地利用数据和SWAT模型模拟数据可以得知,LUCC对研究区的降水入渗量存在着一定的相关性。     

Can additional N fertiliser ameliorate the elevated CO2‐induced depression in grain and tissue N concentrations of wheat on a high soil N background?

Elevated CO₂ stimulates crop yields but leads to lower tissue and grain nitrogen concentrations [N], raising concerns about grain quality in cereals. To test whether N fertiliser application above optimum growth requirements can alleviate the decline in tissue [N], wheat was grown in a Free Air CO₂ Enrichment facility in a low‐rainfall cropping system on high soil N. Crops were grown with and without addition of 50–60 kg N/ha in 12 growing environments created by supplemental irrigation and two sowing dates over 3 years. Elevated CO₂ increased yield and biomass (on average by 25%) and decreased biomass [N] (3%–9%) and grain [N] (5%). Nitrogen uptake was greater (20%) in crops grown under elevated CO₂. Additional N supply had no effect on yield and biomass, confirming high soil N. Small increases in [N] with N addition were insufficient to offset declines in grain [N] under elevated CO₂. Instead, N application increased the [N] in straw and decreased N harvest index. The results suggest that conventional addition of N does not mitigate grain [N] depression under elevated CO₂, and lend support to hypotheses that link decreases in crop [N] with biochemical limitations rather than N supply.     

Soil enzyme activities during the 2011 Texas record drought/heat wave and implications to biogeochemical cycling and organic matter dynamics

Extreme droughts and heat waves due to climate change may have permanent consequences on soil quality and functioning in agroecosystems. During November 2010 to August 2011, the Southern High Plains (SHP) region of Texas, U.S., a large cotton producing area, received only 39.6 mm of precipitation (vs. the historical avg. of 373 mm) and experienced the hottest summer since record keeping began in 1911. Several enzyme activities (EAs) important in biogeochemical cycling were evaluated in two soils (a loam and a sandy loam at 0–10 cm) with a management history of monoculture (continuous cotton) or rotation (cotton and sorghum or millet). Samplings occurred under the most extreme drought and heat conditions (July 2011), after precipitation resulted in a reduction in a drought severity index (March 2012), and 12 months after the initial sampling (July 2012; loam only). Eight out of ten EAs, were significantly higher in July 2011 compared to March 2012 for some combinations of soil type and management history. Among these eight EAs, enzymes key to C (β-glucosidase, β-glucosaminidase) and P cycling (phosphodiesterase, acid and alkaline phosphatases) were significantly higher (19–79%) in July 2011 than in March 2012 for both management histories regardless of the soil type (P > 0.05). When comparing all sampling times, the activities of alkaline phosphatase, aspartase and urease (rotation only) showed this trend: July 2011 > March 2012 > July 2012. Activities of phosphodiesterase, acid phosphatase, α-galactosidase, β-glucosidase and β-glucosaminidase were higher in July 2011 than July 2012 in at least one of the two management histories. Total C was reduced significantly from July 2011 to March 2012 in the rotation for both soils. Only the activities of arylsulfatase (avg. 36%) and asparaginase showed an increase from July 2011 to March 2012 for both soil types, which may indicate they have a different origin/location than the other enzymes. EAs continued to be a fingerprint of the soil management history (i.e., higher EAs in the rotation than in monoculture) during the drought/heat wave. This study provided some of the first evidence of the adverse effects of a natural, extreme drought and heat wave on soil quality in agroecosystems as indicated by EAs involved in biogeochemical cycling.     

The role of green roofs in mitigating Urban Heat Island effects in the metropolitan area of Adelaide,South Australia

Changing an urban environment and replacing vegetated surfaces with low albedo materials is one of the reasons for increasing temperatures in an urban environment and consequently also one of the key causes of urban heat island effects. In this study, an experimental investigation at the micro-scale and also a numerical simulation at the macro-scale of a typical urban environment in Adelaide were conducted to estimate the potential for mitigating the UHI effect. The results showed that existing low albedo materials such as asphalt, metal roofs and brick pavements contribute to the heat island potential. Also, urban development and a lack of natural vegetation contribute to increased temperatures in cities. The ability of two types of extensive and intensive green roofs to reduce the surrounding micro-climate temperature were monitored. The results showed that they have significant cooling effects in summer time and could behave as an insulation layer to keep buildings warmer in the winter. Furthermore, different scenarios of adding green roofs to the Adelaide urban environment were investigated using the Envi–MET model. The scenario modelling of adding green roofs in a typical urban area in Adelaide, Australia, supported the hypothesis that this can lead to reductions in energy consumption in the Adelaide urban environment. Also an increased use of other water sensitive urban design technologies such as green walls and street trees together with the adoption of high albedo materials is recommended for achieving the optimum efficiency in terms of reducing urban temperatures and mitigating urban heat island effects.     

不同施肥措施对灰枣园土壤速效养分含量的影响

为了探讨灰枣生长期内不同施肥处理措施对枣园土壤速效养分含量的影响情况,于2014年3月采用不施肥、常规施肥和施用不同种类生物肥共3大类9种处理进行田间试验,并于同年7~10月在灰枣不同生长期测定了各处理区域土壤中的碱解氮、速效磷、速效钾、有机质这4种养分的含量,研究了不同施肥处理下灰枣不同成熟期土壤各养分的动态变化情况。结果表明,不同处理、不同成熟期土壤各养分含量间均有差异,施用生物肥可以显著提高土壤中各养分的含量。     

1961—2010年东北农作区春小麦需水量的时空变化特征

利用东北农作区58个气象站点1961—2010年的逐日气象数据,基于Simulation of Evapotranspiration of Applied Water(SIMETAW)模型分析气候变化背景下东北农作区春小麦生育期内作物需水量(Crop evapotranspiration,ETc)和灌溉需要量(Evapotranspiration of applied water,ETaw),以及典型站点春小麦的灌溉需求指数(Irrigation demand index,IDI)的时空变化特征。结果表明:近50年来,东北农作区日平均温度呈显著上升趋势,平均降水量下降趋势不明显,平均太阳辐射及作物蒸散量呈显著下降趋势。春小麦生育期作物需水量和灌溉需要量呈下降趋势,其分布均表现为西多东少。50年来春小麦作物生育期需水量下降主要集中于松辽及兴安岭南部地区,东部地区变化趋势不明显;生育期灌溉需要量下降集中于松辽及兴安岭地区,三江平原地区略有增加,长白山地区多年保持平稳。     

Mass balanced based LCA of a common carp-lettuce aquaponics system

An aquaponics system (AS) is an integrated system that combines a recirculating aquaculture system and a hydroponics system (HS). It is designed to recover nutrients released from fish and transfer them to plants to provide a system more environmentally-friendly than the two systems working separately. As a result, several AS are under development, but little information is available about their overall performances. The aim of this study was to assess nutrient-use efficiency and environmental impacts of an AS, specifically a common carp-lettuce AS located in a greenhouse. Nutrient budgets of nitrogen (N) and phosphorus (P) were calculated and Life Cycle Assessment (LCA) was performed for the AS and for a lettuce Individual Hydroponics System (IHS), similar to the HS of the AS, operating in the greenhouse at the same time. The experiment was performed over a 52-day cycle, which corresponds to the growing time required to harvest marketable lettuce. The nutrient budgets were well balanced, with 24.6% of the N unaccounted-for, most likely due to N2 gas emission, and 6.6% of the P unaccounted-for, most likely due to having underestimated the quantity of sediment. At the beginning of the experiment, N represented 55.9%, 37.1% and 0.1% of the total N input in the formulated feed, stocked fish and lettuce seedlings, respectively. At the end of the experiment, N represented 47.6% and 0.4% of the total N input in the harvested fish and lettuce, respectively. At the beginning of the experiment, P represented 56.94%, 40.20% and 0.03% of the total P input in the formulated feed, stocked fish and lettuce seedlings, respectively. At the end of the experiment, P represented 51.52% and 0.42% of the total P input in the harvested fish and lettuce, respectively. LCA clearly indicated two environmental impact hotspots: the origin of nutrients and energy use. One kg of lettuce growth in the AS clearly had lower environmental impacts than that in the IHS for climate change, acidification, eutrophication, land competition and cumulative energy demand; however, a decrease in water dependence was not observed. The indicator for net primary production use highlighted the dependence of the AS on natural resources, especially fish meal and fish oil. Compared to the use of chemical nutrients in the IHS, the use of nutrients from formulated feed in the AS decreased climate change impact but increased the use of natural resources.     

宁夏中部生态移民区土地利用时空变化分析

通过解译宁夏中部红寺堡区1989年、1999年、2006年、2012年TM遥感影像,获取该区域生态移民前后4期土地利用数据,对1989~2012年以来土地利用变化情况进行了分析。结果表明,各个时间段的土地利用变化差异性显著。1989~1999年,由于大规模的土地开荒和红寺堡灌区的建设,耕地面积持续增加,同时该区域开始有了水浇地,而林草面积相应减少;1999~2006年,由于退耕还林还草政策的实施,耕地中的旱地被逐渐退耕为草地或发展为水浇地,林草面积开始由减少转为增加,区域土地利用开始合理化;2006~2012年,随着生态移民工程和生态建设工程的成熟发展,林草覆盖面积进一步增加,水浇地面积继续稳步增加,而未利用地和旱地面积持续下降。研究结果为区域土地资源的合理利用及生态移民工程的进一步顺利开展提供可靠依据。