大葱采种方式对分蘖率的影响

根据大葱不同采种方式对分蘖率的影响,提出大葱网棚采种方式隔离效果最好,宜用于繁育原种;应用隔离采种方式进行良种繁育时,隔离区必须超过1 000 m.     

海南地区国家自然科学基金申报命中率影响因素分析及对策研究

以海南地区近几年申报国家自然科学基金的基础数据为依据,分析该地区科学基金申报、获资助情况现状,并着重分析影响该地区科学基金申报命中率的主要因素,从国家科技政策、申报策略、申报工作组织等方面提出对相应的对策建议。     

Cadmium Accumulation in Agricultural Soils in Western Australia

Water, Air, & Soil Pollution - Phosphatic fertilizers contain appreciable concentrations of cadmium (Cd) which may elevate the Cd concentrations of soils and crops, yet the impact of Cd on...     

海南岛农用地土壤重金属元素的空间分布特征及其环境意义

采用现场采样及室内分析测试方法,对海南岛26个农业土壤剖面淋溶层、淀积层、母质层中7种重金属元素的分布特征进行研究.结果发现,重金属元素在淋溶层和淀积层的含量变化幅度与母质层含量变化幅度具有一定的正相关关系,土壤重金属分布在总体上受成土母质层制约.除As、Pb外,大部分重金属元素在各层中的含量低于世界土壤平均值,但也有部分重金属元素通过淋溶使表层土壤中少量重金属元素迁移而至淀积层中积累.除Cd有机态含量最低外,各层中重金属元素在淋溶层、淀积层、母质层中均显示可交换态含量最低,而残渣态含量最高.区内土壤表层7种重金属分布总体上可归为3类:Cr、Ni、Cd 3种重金属元素的土壤表层平均含量较低,变异系数小,表层元素主要继承于母质层;Cu、Zn组中的Zn可能存在一定的外源混入,但Cu、Zn在土壤表层未发生富集;而As、Pb等重金属元素不仅有外源混入,且发生了一定程度积累,为区内土壤主要的环境隐患.     

Distribution of Heavy Metals in Near-Shore Sediments of the Swan River Estuary,Western Australia

Estuarine systems adjacent to urban areas are at risk of contamination by contaminants from anthropogenic sources, such as heavy metals. We anticipated that the sediments of the Swan River estuary, which runs through metropolitan Perth in Western Australia, would show metal contamination related to industrialization and inputs of stormwater. Total Cu, Pb and Cd concentrations, and Cu, Pb, Cr and Zn inoperationally-defined fractions, were determined inseparate sampling exercises in near-shore sediments ofthe upper Swan River estuary.Total metal concentrations in sediments were not high (maximum values of 297 mg kg^-1 for Cu, 184 mg kg^-1 for Pb and 0.9 mg kg^-1 for Cd) when compared with Australian environmental assessmentguidelines for soils. On the basis of linear regressions between sediment metal concentrations andphysicochemical properties of the sediments (pH, organic carbon, particle size distribution), no single parameter could explain the variation in metal concentrations for all metals. Sediment organic carbon content was positively correlated with Cu concentration; Cu concentrations also increased significantly with increasing clay content anddecreasing sand content. Pb concentrations showed a significant increase with increasing sediment pH, and were approximately three-fold higher in sediments adjacent to stormwater drain outfalls than in sediments remote from drains; no such effect was observed for Cu or Cd. No effect of distance downstream was observed. Sequential extraction of sediments showed that most of the metals were in relatively immobile forms, for example bound to Feoxides, or only extractable by aqua regia. The enhanced concentrations of Pb near stormwater outfalls suggest that vehicle-derived Pb may be an important contributor of Pb to the estuary.     

肉仔鸡血清蛋白质、钙、磷和睾酮含量与生长发育的关系

本文通过对不同品种肉鸡进行饲养观察,初步认定罗曼鸡生长发育最快。其饲料转化率、适应性、抗病力等明显优于AA和星布罗肉鸡。从理论上阐述了影响肉鸡生长发育的生理因素。试验分析表明,血清中总蛋白质含量与生长速度成正相关;血清钙和无机磷含量,在不同肉鸡品种之间差异不大;公鸡血清睾酮含量对肉鸡生长发育有一定促进作用,睾酮含量多的肉鸡生长发育快,一般表现出体重与血清睾酮之间有明显的相关。     

Organic Substrates in Bioremediation of Acidic Saline Drainage Waters by Sulfate-Reducing Bacteria

Deep drains used to manage shallow saline water tables in the Western Australian agricultural region discharge acidic, saline drainage water with high concentrations of metals. The activity of sulfate-reducing bacteria can treat these waters by generating alkalinity in the form of bicarbonate and by generating sulfide, which removes metals from solution as sulfide precipitates. Bacterial sulfate reduction was strongly influenced by the organic carbon substrate provided for bacterial consumption. Mixtures of lupin compost, wheat chaff, oil mallee distillate wastes, straw, ethanol, and sheep manure were compared to determine which substrate was most effective in promoting the activity of sulfate-reducing bacteria and the contribution of this to bioremediation of acidic saline drainage. Mesocosm treatment systems containing reactive mixtures and acidic saline drainage were operated for a 50-day establishment period and subsequent 27-day “batch flow” period. Effluent from the treatment systems was analyzed for pH, sulfate, metals, and nutrients over the period of operation. Effluents from all reactive mixtures showed increased pH (to 5.1–5.9) and decreased sulfate and metal concentrations compared with untreated drainage water. Straw with ethanol appeared to be the most effective substrate for treatment of low pH and high metal concentrations, followed equally by both lupin compost and wheat chaff. The latter are likely to be more suitable for use in a field scale low-maintenance bioreactor or composting wetland.