紫色丘陵区小流域典型降雨径流氮磷流失特征

对2007年盐亭小流域两场典型降雨(施肥后首场大雨和大暴雨)的径流过程进行了连续监测,同步测定了径流量、氮磷浓度,旨在阐明农业小流域典型降雨氮磷流失随降雨径流的变异规律.结果表明,流量曲线与浓度过程线变化趋势一致.整个径流过程中的氨态氮(AN)与磷酸盐(PO3-4-P)浓度较低且波动较小.初期径流颗粒态氮(PN)、颗粒态磷(PP)与总磷(TP)的浓度高于后期径流,初期冲刷效应明显.颗粒态氮(PN)是氮素在径流初期迁移的主要形态,而后期以硝态氮(NN)为主;但PP是整个径流过程中的主要迁移形态.初期径流中AN、PN、TP、PP及泥沙(SS)负荷分布较大,而硝态氮(NN)、总氮(TN)和PO3-4一P则主要分布在径流后期.污染物初期冲刷和NN后期淋溶是暴雨径流氮素流失的主要原因,而施肥后首场降雨氮素流失的主要原因是NN淋溶.暴雨径流产生氮磷负荷巨大,TN与TP分别为167.04kg和20.75 kg;而施肥后首场大雨径流氮磷流失负荷较小,分别为12.07 kg(TN)、1.04 kg(TP),其中60%的TN以NN流失.     

Anthelmintic resistance in New Zealand: A perspective on recent findings and options for the future

A recent national survey on anthelmintic resistance in cattle and sheep in New Zealand indicated that the magnitude of the problem has increased from very low levels only a few years ago to disturbingly high levels now. There is a particular problem with multiple resistance to all three action families of anthelmintic currently available in Ostertagia (= Teladorsagia) spp in sheep, and to both macrocyclic lactones (ML) and benzimidazoles in Cooperia spp in cattle. The prevalence and extent of resistance indicate that all cattle farmers and most sheep farmers should now be using a combination anthelmintic on most occasions just to achieve effective control of all parasites. Despite this, the presence of resistant parasites has generally not been appreciated by the majority of affected farmers, possibly because most have not formally tested to determine the resistance status of nematodes on their farms.

Anthelmintics will remain the cornerstone of gastrointestinal nematode control in sheep and cattle for the foreseeable future but to ensure their continued effectiveness farmers need to be constantly aware of the need to maintain adequate reservoirs of unselected nematodes, i.e. worms in refugia, to minimise the expansion of the resistant population. High-risk practices in relation to selection of resistance need to be identified and avoided or at least their use limited. These include: treating adult animals where there is no identified need, moving newly- treated animals onto ‘clean’ pasture, and failing to effectively quarantine-drench bought-in animals. None of these are new concepts but many have not been adopted or practised. In particular, sheep farmers should endeavour to avoid treating ewes pre-lambing with long-acting anthelmintics. Farmers needs to negotiate a balance between achieving good parasite control and the sustainability of their control options.     

A study of neonatal cryptosporidosis of foals in New Zealand

Abstract

AIM: To assess the occurrence of Cryptosporidium oocysts in faecal specimens from foals, and investigate an outbreak of neonatal cryptosporidiosis in foals revealed in the course of the study.

METHODS: Faecal specimens from foals received by a diagnostic veterinary laboratory in New Zealand between 2006 and 2007 were submitted to Massey University and tested microscopically for the presence of Cryptosporidium oocysts. The Cryptosporidium isolates in the oocyst-positive specimens were genetically identified to species level. In addition, specimen submission data from the participating laboratory for 2005–2007 were examined. In the course of the study, the identification of one Cryptosporidium-positive specimen triggered an on-farm investigation.

RESULTS: Twelve faecal specimens submitted by the participating laboratory between 2006 and 2007 were tested further, and three were positive for C. parvum. Specimen submission records indicated a total of 67 faecal specimens were tested for Cryptosporidium by the participating laboratory between 2005 and 2007; 12 (18%) were positive. The on-farm investigation on a broodmare farm revealed a high incidence of neonatal diarrhoea in foals; C. parvum was the only enteropathogen found in the faeces of 4/4 affected foals examined. The diarrhoea in all those foals was self-limiting, manifesting during the second week of life, resembling foal heat diarrhoea, and accompanied by a short but intense period of shedding oocysts.

CONCLUSIONS AND CLINICAL RELEVANCE: The fact that Cryptosporidium parasites were identified in 18% of faecal specimens from foals analysed for this agent in 2005–2007 by the participating laboratory indicated that infection with this agent in foals is not uncommon.

Collectively, the results of this and previous studies performed in New Zealand indicate C. parvum is a cause of diarrhoea in newborn foals, potentially accounting for a proportion of cases empirically diagnosed as foal heat diarrhoea. It is therefore advisable to take precautions when handling diarrhoeic foals, until this potentially zoonotic agent is ruled out in the laboratory.     

再生水灌溉对甘蓝品质和重金属累积特性影响研究

采用天津市纪庄子污水处理厂二级出水作为再生水,以自来水为对照进行甘蓝栽培大田灌溉试验,研究了再生水灌溉对甘蓝品质、微量元素和重金属累积特性的影响。结果表明:再生水灌溉对甘蓝维生素C含量、粗蛋白含量、可溶性糖含量影响与自来水灌溉相比,各处理间检验差异未达到显著性水平;短期再生水与自来水混灌或轮灌对甘蓝微量元素Na、Mg、K、Ca和Zn含量与自来水灌溉间无显著性差异;甘蓝地上部中重金属镉、铅、砷、铬含量虽均低于国家卫生标准(GB 15201—1994、GB 14935—1994、GB 4810—1994和GB 14961—1994)规定,且与自来水灌溉对照间不存在显著性差异。     

蜂产品可溯源监控体系

在介绍食品溯源的概念和意义的基础上,对我国建立蜂产品溯源监控体系的紧迫性和存在的问题,如何建立蜂产品溯源监控体系以及蜂产品溯源监控体系中几个关键技术(以蜂蜜为例)提出了一些建议.     

以光周期处理与分期播种试验综合鉴定大豆品种的光温反应

设置短日照(12 h)和长日照(16 h)两种光周期处理,并以春播模拟低温、夏播模拟高温条件,形成长日+低温、长日+高温、短日+低温、短日+高温4种光温组合。2007年对近年育成的10个北方春大豆[Glycine max (L.) Merr.]品种(系)和18个黄淮海夏大豆品种(系)进行了光温反应特性鉴定。2008年对50份材料进行了光周期反应鉴定。结果表明,不论在低温(春播)还是高温(夏播)条件下,短日照均加快大豆的发育进程,导致开花提前;不论在长日照还是短日照条件下,高温均减少出苗至初花的日数。光周期和温度对大豆的发育存在明显的互作,随着温度的升高,短日照促进大豆发育的效应有所加强;随着日照的缩短,高温加快发育的作用也有所增大。供试大豆品种生态类型在光周期反应敏感度(PRS)、温度反应敏感度(TRS)及光温综合反应敏感度(PTCRS)等方面均存在显著差异。北方春大豆品种的上述3个指标均小于黄淮海夏大豆品种,但前者在不同光照条件下的温度反应敏感度差值和在不同温度条件下的光周期反应敏感度差值均较后者高,说明北方春大豆品种光温互作效应较强。     

The Solar Acoustic Spectrum and Eigenmode Parameters

The Global Oscillation Network Group (GONG) project estimates the frequencies, amplitudes, and linewidths of more than 250,000 acoustic resonances of the sun from data sets lasting 36 days. The frequency resolution of a single data set is 0.321 microhertz. For frequencies averaged over the azimuthal order m, the median formal error is 0.044 microhertz, and the associated median fractional error is 1.6 x 10(-5). For a 3-year data set, the fractional error is expected to be 3 x 10(-6). The GONG m-averaged frequency measurements differ from other helioseismic data sets by 0.03 to 0.08 microhertz. The differences arise from a combination of systematic errors, random errors, and possible changes in solar structure.     

酸度对胡敏酸与镉和锌离子络合反应的影响

用离子交换平衡法研究了不同pH下胡敏酸与锌、镉单独及复合存在下形成络合物的稳定性及配位数.结果表明：在Zn^2＋,Cd^2＋单独存在时,络合反应的稳定常数及配位数随着pH值的增大而增大;相同pH条件下,Zn^2＋和胡敏酸络合物的稳定常数及配位数大于Cd^2＋.在Zn^2＋,Cd^2＋复合存在时,pH的变化与胡敏酸络合金属离子的稳定常数及配位数没有明显依存关系;与单独存在时相比,在pH 3.5和pH7.0时,Zn^2＋,Cd^2＋和胡敏酸络合物的稳定常数和配位数都减小;而在pH 5.0时,Cd^2＋和胡敏酸络合物的稳定常数和配位数都增大,Zn^2＋和胡敏酸络合物的稳定常数和配位数都减小.     

花蛤高效生态养殖池中浮游动物生态特征研究

于2007年11月-2008年3月,研究莆田花蛤生态养殖池浮游动物的种类组成和数量分布特征,并探讨了其与环境因子的关系。结果表明,在藻类池及花蛤养殖池中所采集的样品,浮游动物有34种,其中原生动物25种,占74％,桡足类5种,占15％,端足类1种,占2．9％,其它浮游动物3种,占8．8％,原生动物占比例最多。卡拉拟铃虫,丁丁急游虫、浮游幼虫和强额拟哲水蚤是主要优势种。不同月份浮游植物数量变化直接影响着浮游动物的数量,浮游动物的数量受海水温度、溶氧影响不大,不同月份浮游动物的分布存在差异。