呼伦贝尔露天煤矿堆土场外围牧场土壤的重金属污染评价

为露天煤矿矿区的土壤改良与修复提供依据,采用单因子污染指数法、内梅罗综合污染指数法与Hakanson潜在生态指数法相结合对呼伦贝尔市东明露天煤矿堆土场外围东南侧牧场土壤Cr、Cu、Zn、Cd、Pb、As和Hg等7种重金属的含量特征、污染程度与潜在生态风险进行研究,同时运用相关分析及主成分分析探讨牧场土壤重金属的主要来源。结果表明:牧场土壤7种重金属含量与国家土壤环境质量标准(GB15618—1995)二级标准相比均未超过规定限值,与内蒙古土壤重金属背景值相比,Zn和Pb的含量均超标,超标率为5.56%和83.33%。牧场土壤7种重金属的单项污染指数均1,土壤污染等级为清洁;综合污染指数0.7,土壤污染等级为安全。Cd的潜在生态危害系数平均值为53.04(40),呈中等生态危害程度,其他金属均为低生态危害程度;7种重金属综合潜在生态危害指数平均为86.43(90),呈轻微生态危害程度。主要贡献因子是Cd。Cu、Zn、Cd与Pb及As与Hg具有相同来源的可能性大,Cr具有单独的污染来源。     

西藏地区不同牧草体外发酵特性研究

本文旨在利用体外产气法评定西藏地区不同牧草营养价值。选取西藏地区5种常见牧草,通过单因素试验设计,利用体外产气法评定5种牧草体外发酵48 h累积产气量、理论最大产气量(V_f)、初始产气速率(FRD_0)、达到最大产气量一半时所需时间(t_(0.5))、体外干物质消失率(IVDMD)、体外中性洗涤纤维消失率(IVNDFD)、p H、氨态氮(NH_3-N)浓度以及挥发性脂肪酸(VFA)产量。结果表明,体外发酵48 h后,苇状羊茅体外48 h累积产气量、V_f、FRD_0、IVDMD及甲烷(CH_4)、乙酸、丙酸、丁酸和总VFA产量均显著高于其他4种牧草(P0.05),但其体外发酵p H及乙酸/丙酸显著低于其他4种牧草(P0.05);紫花苜蓿体外NH_3-N浓度最高,显著高于其他4种牧草(P0.05)。综上分析,苇状羊茅体外发酵效果最佳,与其他试验牧草相比,更容易被瘤胃微生物降解利用。     

Nitrous oxide fluxes and denitrification sensitivity to temperature in Irish pasture soils

Nitrous oxide (N₂O) emissions from grazed pastures constitute approximately 28% of total global anthropogenic N₂O emissions. The aims of this study were to investigate the effect of inorganic N fertilizer application on fluxes of N₂O, quantify the emission factors (EFs) for a sandy loam soil which is typical of large areas in Ireland and to investigate denitrification sensitivity to temperature. Nitrous oxide flux measurements from a cut and grazed pasture field for 1 year and denitrification laboratory incubation were carried out. The soil pH was 7.3 and had a mean organic C and N content at 0–20 cm of 44.1 and 4.4 g/kg dry weight, respectively. The highest observed peaks of N₂O fluxes of 67 and 38.7 g N₂O‐N per hectare per day were associated with times of application of inorganic N fertilizer. Annual fluxes of N₂O from control and fertilized treatments were 1 and 2.4 kg N₂O‐N per hectare, respectively. Approximately 63% of the annual flux was associated with N fertilizer application. Multiple regression analysis revealed that soil nitrate and the interaction between soil nitrate and soil water content were the main factors controlling N₂O flux from the soil. The derived EF of 0.83% was approximately 66% of the IPCC default EF value of 1.25% as used by the Irish EPA to estimate greenhouse gases (GHGs) in Ireland. The IPCC‐revised EF value is 0.9%. A highly significant exponential regression (r² = 0.98) was found between denitrification and incubation temperature. The calculated Q₁₀ ranged from 4.4 to 6.2 for a temperature range of 10–25 °C and the activation energy was 47 kJ/mol. Our results show that denitrification is very sensitive to increasing temperature, suggesting that future global warming could lead to a significant increase in soil denitrification and consequently N₂O fluxes from soils.     

Management options to decrease phosphorus and sediment losses from irrigated cropland grazed by cattle and sheep

In southern New Zealand, grazing of forage crops is common practice to satisfy feed requirements of animals in winter when pasture growth is limited. This practice has been shown to cause soil physical damage and increased loss of surface water contaminants sediment and phosphorus (P) to water bodies. Strategies to mitigate the loss of sediment and P were trialled on a Pallic soil type (Aeric Fragiaquept) in the North Otago Rolling Downlands of New Zealand. All sites were irrigated and measurements were made of losses in overland and sub‐surface flow from intensive cattle or sheep grazed, winter forage crops, and sheep grazed pasture. Two mitigations (restricted grazing of crop to three hours and the application of aluminium sulphate) were assessed for their potential to decrease contaminant loss from cropland. Volumes of surface runoff and loss of total P, filterable reactive P and sediment showed significant differences (P < 0.05) between the control treatments (i.e. no mitigation) with cattle crop (88 mm surface runoff) > sheep crop (67 mm) > sheep pasture (33 mm). The contribution of irrigation water to overland flow water, as a result of saturation‐excess conditions, varied between treatments with more loss under cattle crop (20% of total) compared with sheep crop (15%) and sheep pasture (11%). These differences are probably an effect of soil physical condition and highlight the importance of accurate irrigation scheduling to keep soil moisture below field capacity. Restricted winter grazing and alum application after grazing significantly (P < 0.05) decreased P losses in surface runoff under cattle (from 1.4 to 0.9 kg P/ha) and sheep (from 1.0 to 0.7 kg/P/ha) grazed crop plots by about 30%. In cattle grazed plots, restricted grazing also decreased suspended sediments (SS) by 60%. The use of restricted grazing is suggested as a means of decreasing P and SS loss from grazed winter forage crops. The use of alum shows some promise for decreasing P losses, but requires further work to determine its long‐term effectiveness and use in other soils and management regimes.     

用钙电极测定牧草中钙含量的方法研究

用钙电极测定禾本科牧草中钙含量的方法，回收率１００．０２％－９７．３８％，用高酸钾法的ＥＤＴＡ法与钙电极法作比较试验，结果非常满意。     

龙羊峡库区天然草地动态分析

利用美国陆地卫星T.M图象,对龙羊峡水库库区的天然草地进行了对比分析。结果表明,天然草地面积减少7084.09hm^2。其中减幅较大的为温性草原类和温性荒漠类,10年中分别减少了7299.27hm^2和1015.65hm^2。另外,草地盖度,牧草高度和草地产量也有下降,其中草地盖度下降5%-15%;牧草种数减少4-20种;牧草产量下降73.5-1090.05kg/hm^2。并对变化原因作了分析,提出了治理措施。     

The Effect of Supplementation with Fresh Browse of Ziziphus mauritiana or Combretum aculeatum on Feed Intake,Nitrogen Utilization and Growth of Grazing Range Sheep

The influence of 0, 60 or 120 min access to a grove of either Ziziphus mauritiana (Ziziphus) or Combretum aculeatum (Combretum) on forage intake and on the digestibility, growth and excretion of nutrients was determined using 40 Oudah rams grazing for 7 h/day on poor-quality dry season pasture in the Sahel. The effects of browse species and browsing duration (0, 30, 60 or 120 min) on the ruminal ammonia content were also evaluated using 8 mature fistulated rams. Ziziphus increased both total digestible organic matter and total dry matter intakes per (kg live weight)^0.75 without decreasing herbage intake, whereas 60 or 120 min access to Combretum reduced herbage intake by 6.3% and 4.2%, respectively. The digestibility of the diet decreased (p<0.05) with the duration of access to the groves. Despite the provision of more nitrogen (N) than in the control diet, ruminal NH₃-N decreased 24 h after browsing commenced. The reduced live weight gain of sheep browsing Combretum may indicate more deleterious compounds in Combretum than in Ziziphus. Ziziphus appears to have more potential than Combretum to increase sheep production in low-input crop/livestock systems.     

The Effect of Anthelmintic Capsules on the Egg Output and Larval Viability of Drug-resistant Parasites

Challenge with an equal mix of drug-resistant and drug-susceptible larvae of Teladorsagia circumcincta resulted in infections in groups of lambs (n = 6) either untreated or given controlled-release capsules, containing either albendazole or ivermectin. Lambs treated with albendazole capsules contained similar numbers of adult worms at necropsy to the other groups but had no detectable faecal egg count. Animals treated with ivermectin capsules had similar worm burdens and faecal egg counts to the control group but the worms had significantly higher numbers of eggs in utero. These results provide evidence for suppression of egg production by both anthelmintic treatments. The observation that albendazole caused a significant reduction in the developmental success of parasite eggs also has implications for the use of faecal egg count as an indicator for pasture contamination with resistant parasites. In two further groups of lambs, either untreated or given albendazole capsules, treatment caused a significant reduction in egg count and adult worm burden of Trichostrongylus colubriformis. No significant effects were observed on in utero egg counts or egg viability and the apparent effect on the number of eggs produced in faeces per adult female was not significant (p = 0.077). There was, therefore, no evidence that albendazole controlled-release capsules caused suppression of egg output in this species.     

高寒牧区陶赛特绵羊鲜胚移植试验观察

选取兰州信合牧业34只陶赛特绵羊为供体，采用递减法注射FSH进行超排，采用人工授精配种，30只长途运输到青海省海北州西海镇手术法回收胚胎，鉴定后移值。155只藏系绵羊作为受体，采用两次PG注射进行同期发情，119只受体在西海镇移植，32只长途运输到甘肃兰州信合牧业进行移植。结果表明：34只供体获得胚胎共168枚，每只供体平均获得4．94枚，合格率89．88％，151只受体表现发情，发情率为97．42％。其中．在西海镇移植的119只产羔73只，产羔率为61．34％，在兰州移植的32只产羔21只，产羔率为65．6％。