外源铅在红壤中的迁移和形态转化     

王旭  颜丽  关连珠 《安徽农业科学》2012,(7):4243-4244

[目的]为污染土壤的控制和修复治理提供科学依据。[方法]采用实验室土柱法,研究外源铅在红壤中的迁移和形态转化。[结果]在水分不饱和条件下,外源水溶性铅进入红壤90 d后并未向15～30 cm土层迁移,而是集中在0～15 cm层次;外源水溶性铅进入红壤(0～15 cm)30 d后水溶态迅速向其他形态转化,其形态分布主要以交换态为主,其次为铁锰氧化物态、残渣态、碳酸盐结合态、有机结合态(未检出)。[结论]外源铅进入红壤90 d后绝大部分还未转化为相对稳定的形态,对土壤—植物系统的污染存在着潜在的危害。红壤(0～15 cm)对外源铅的吸附主要通过离子交换和络合(或螯合)作用。  相似文献   

18—19世纪中期英国交通运输的建设与农业市场的扩展     

叶明勇 《古今农业》2009,(3):19-28

18世纪中期至19世纪中期英国接连掀起公路、运河和铁路建设的高潮，三者共同形成一个全国性的交通网络，这对于沟通农业与市场的联系起了很大促进作用。农业所需物资及农产品通过发达的交通能迅速便利地交流，大大降低了成本、提高了效率。英国农民对市场反应的灵敏也有赖于此，从某种程度上讲也就刺激了农业生产。另一方面，交通运输网络的形成又促进了市场的扩大与完善，这对于英国农业，对于英国整体经济的发展都有重大的意义。  相似文献   

14C同化物在黄柏韧皮部的运输速率测定     

严晓宇  叶萌  彭煜程  夏先福  赵敏  蒋燕  张岚 《林业科技开发》2007,21(2):60-61

以14C为示踪剂,用14CO2 CO2混合气体法进行半株标记,饲喂50μCi/株的NaH14CO3,标记时间为lh.燃烧法制样,在FJ2107P液体闪烁计数器上测定,14C同化物在黄柏韧皮部中的运输速率为47～54 cm/h,平均速率为50.2 cm/h.  相似文献   

Transportation and handling stress of white suckers raised in cages   总被引：1，自引：0，他引：1  

Janice Bandeen  John F. Leatherland 《Aquaculture International》1997,5(5):385-396

Changes in plasma cortisol concentrations were measured in juvenile white suckers, Catostomus commersoni (Lacepede), as a measure of their response to transportation (8 h) and chase challenge stressors. The study attempted to evaluate the ability of this species to withstand standard aquacultural husbandry practices. Plasma cortisol concentrations were elevated during and following transportation. Recovery from transportation (as plasma cortisol levels reached baseline values) was prolonged in fish transported under winter conditions compared with fish transported during the summer months. The plasma cortisol response to a 5 min chase challenge in well-fed juvenile white suckers was typically of 2 to 3 h periodicity with the peak values between 15 and 30 min. This pattern was similar in fish fed three commercial diets (although rates of recovery differed), and was unaffected by fasting. The return of plasma cortisol concentrations to baseline values following the chase-challenge stressor was prolonged in fasted groups. The results of this study showed that juvenile white suckers require several days to recover from transportation and under the acclimation conditions applied, the recovery was faster in the fish transported during the summer.  相似文献   

Efficient management of transportation logistics related to animal disease outbreaks     

H. Vernieuwe  E. Ducheyne 《Computers and Electronics in Agriculture》2010,71(2):148-157

Vehicle routing is a key instrument to manage and control animal disease outbreaks. This paper focuses on an efficient, user-friendly and automatic procedure to manage transportation logistics to and between farms in the case of an outbreak. This procedure can be embedded into a veterinary geographical information system for the management and control of disease outbreaks. The transportation logistics for the problem at hand can be divided into two main transportation categories: (i) round itineraries, which are special cases of the travelling salesman problem, and (ii) one-to-one itineraries. Attention is given to the use of user-friendly, heuristic yet efficient algorithms for the determination of these itineraries. It is furthermore shown that the procedure is developed in such a way that the identified routes meet both national and international regulations in force during disease outbreaks.  相似文献   

杂种小麦生育规律的研究 Ⅰ开花后光合产物的积累及对产量的影响     

蒋纪芸  冯佰利  张保军  杨惠侠 《西北农业学报》1992,1(3):31-36

采用称重法研究了杂种与常规品种开花后顶三叶、鞘、茎节间干物质变化过程的结果表明,杂种小麦营养体内光合产物的生产量具有优势,单茎增长量较常规品种多22%,但由于输往穗子的光合产物比常规品种少10%,因而杂种产量优势不显著。  相似文献   

灰色-马尔柯夫链预测棉花产量(单产)   总被引：6，自引：0，他引：6  

祁宦  王颖  王父 《安徽农业科学》2002,30(1):152-154

灰色预测和马尔柯夫链预测方法都可用于时序问题的预测,在农作物产量预报中,2种方法各有局限性,单独使用预测准确率都不高,特别是对时序波动较大的棉花产量预测,二者的局限性表现更为明显.笔者将2种方法结合起来使用,建立了宿州市棉花产量(单产)的预测模型,在实际应用中,取得了较为满意的效果,历史拟合率小于4.5%,1999、2000年试报准确率分别达97.8%和96.9%.  相似文献   

Transmission of methicillin resistant Staphylococcus aureus among pigs during transportation from farm to abattoir     

Els M. Broens  Elisabeth A.M. Graat  Peter J. Van Der Wolf  Arjen W. Van De Giessen  Mart C.M. De Jong 《Veterinary journal (London, England : 1997)》2011,189(3):302-305

The prevalence of methicillin resistant Staphylococcus aureus (MRSA) in pigs at abattoirs is higher than in pigs sampled on farms. This study investigated whether MRSA negative pigs can become MRSA positive during transportation from the farm to the abattoir after exposure to other pigs and environmental sources of MRSA. Nasal swabs were collected from four batches of pigs during loading at the farm, on arrival at the abattoir and after stunning. Environmental wipes were taken from lorries after transporting pigs and from lairages after holding pigs. All pigs (n = 117) tested MRSA negative before transportation. On arrival at the abattoir, 12/117 (10.3%) pigs in two batches tested MRSA positive. In lorries that tested positive after transportation, the prevalence of MRSA positive pigs was 21.1%, whereas no MRSA was detected in pigs that had been transported in lorries that tested negative after transportation. At stunning, all batches and 70/117 (59.8%) pigs tested MRSA positive. Pigs can become MRSA positive in the short period of time during transportation from the farm to stunning at the abattoir.  相似文献   

The impact of high speed, high volume traffic axes on brown bears in Slovenia   总被引：1，自引：0，他引：1  

Petra Kaczensky  Felix Knauer  Blaz Krze  Miha Adamic 《Biological conservation》2003,111(2):191-204

The Ljubljana-Razdrto highway and the parallel Ljubljana-Trieste railway cut through critical brown bear (Ursus arctos) habitat in south-central Slovenia. These high speed, high volume traffic axes are located close to the main dispersal corridor for bears from the Dinaric Mountain range into the Alps. We analyzed radiotracking data of 15 individual bears that lived within 10 km of the highway, compared transportation related and overall known bear mortality, and analyzed the spatial distribution of bear-vehicle accidents. The highway posed a home range boundary to resident bears, but was not an absolute barrier. Transportation-related mortality was high in the vicinity of the highway and railway, and averaged 31% of the total known local mortality from 1992 to 1999. At present the detrimental impact of transportation routes on the bear population in Slovenia is modest due to the high density of bears and the low density of highways—but new highways are planned or already under construction. Managers have to be aware that, due to bears large home ranges and long dispersal distances, a single highway affects bears from a huge area—emphasizing the importance of international cooperation and a landscape approach in highway planning.  相似文献   

Haematology and behaviour of pullets transported by road and administered with ascorbic acid during the hot-dry season   总被引：1，自引：0，他引：1  

Minka NS  Ayo JO 《Research in veterinary science》2008,85(2):389-393

The effects of ascorbic acid (AA) on pullets transported by road for 6h during the hot-dry season were investigated. Forty Shika Brown pullets administered orally with AA just before transportation served as experimental, while another 40 pullets given sterile water only served as control. Blood samples analyzed before and after transportation in control pullets showed a decrease (P<0.05) in packed cell volume and haemoglobin values, and a significant (P<0.05) increase in the values of heterophil/lymphocyte ratio, total protein and basophil counts post-transportation. In experimental pullets, the post-transportation values were not different (P>0.05) from those obtained pre-transportation. The result showed that the transportation was stressful in control pullets. The behavioural activities of the pullets' post-transportation period indicated that AA facilitated the transition of the state of depression that followed excitation back to excitation immediately after transportation. In conclusion, AA administration ameliorated the adverse effect of road transportation stress during the hot-dry season.  相似文献