Vegetative buffers for fan emissions from poultry farms: 2. ammonia,dust and foliar nitrogen

This study evaluated the potential of trees planted around commercial poultry farms to trap ammonia (NH₃) and dust or particulate matter (PM). Norway spruce, Spike hybrid poplar, hybrid willow, and Streamco purpleosier willow were planted on five commercial farms from 2003 to 2004. Plant foliage was sampled in front of the exhaust fans and at a control distance away from the fans on one turkey, two laying hen, and two broiler chicken farms between June and July 2006. Samples were analyzed for dry matter (DM), nitrogen (N), and PM content. In addition, NH₃ concentrations were measured downwind of the exhaust fans among the trees and at a control distance using NH₃ passive dosi–tubes. Foliage samples were taken and analyzed separately based on plant species. The two layer farms had both spruce and poplar plantings whereas the two broiler farms had hybrid willow and Streamco willow plantings which allowed sampling and species comparisons with the effect of plant location (control vs. fan). The results showed that NH₃ concentration h^{? 1} was reduced by distance from housing fans (P ≤ 0.0001), especially between 0 m (12.01 ppm), 11.4 m (2.59 ppm), 15 m (2.03 ppm), and 30 m (0.31 ppm). Foliar N of plants near the fans was greater than those sampled away from the fans for poplar (3.87 vs. 2.56%; P ≤ 0.0005) and hybrid willow (3.41 vs. 3.02%; P ≤ 0.05). The trends for foliar N in spruce (1.91 vs. 1.77%; P = 0.26) and Streamco willow (3.85 vs. 3.33; P = 0.07) were not significant. Pooling results of the four plant species indicated greater N concentration from foliage sampled near the fans than of that away from the fans (3.27 vs. 2.67%; P ≤ 0.0001). Foliar DM concentration was not affected by plant location, and when pooled the foliar DM of the four plant species near the fans was 51.3% in comparison with 48.5% at a control distance. There was a significant effect of plant location on foliar N and DM on the two layer farms with greater N and DM adjacent to fans than at a control distance (2.95 vs. 2.15% N and 45.4 vs. 38.2% DM, respectively). There were also significant plant species effects on foliar N and DM with poplar retaining greater N (3.22 vs. 1.88%) and DM (43.7 vs. 39.9%) than spruce. The interaction of location by species (P ≤ 0.005) indicated that poplar was more responsive in terms of foliar N, but less responsive for DM than spruce. The effect of location and species on foliar N and DM were not clear among the two willow species on the broiler farms. Plant location had no effect on plant foliar PM weight, but plant species significantly influenced the ability of the plant foliage to trap PM with spruce and hybrid willow showing greater potential than poplar and Streamco willow for PM_2.5(0.0054, 0.0054, 0.0005, and 0.0016 mg cm^{? 2}; P ≤ 0.05) and total PM (0.0309, 0.0102, 0.0038, and 0.0046 mg cm^{? 2}, respectively; P ≤ 0.001). Spruce trapped more dust compared to the other three species (hybrid willow, poplar, and Streamco willow) for PM₁₀ (0.0248 vs. 0.0036 mg cm^{? 2}; P ≤ 0.0001) and PM_{> 10} (0.0033 vs. 0.0003 mg cm^{? 2}; P = 0.052). This study indicates that poplar, hybrid willow, and Streamco willow are appropriate species to absorb poultry house aerial NH₃–N, whereas spruce and hybrid willow are effective traps for dust and its associated odors.     

Residues levels of organochlorine pesticide in cow's milk from industrial farms in Hidalgo,Mexico

A survey was carried out from 2008 to 2010 to determine the concentrations of 16 organochlorine pesticide residues (OPRs) from Tizayuca, Hidalgo, Mexico. Organochlorine residue determinations were made from milk fat, using chromatographic cleanup and analysis by gas chromatography with an electron capture detector. The OPR concentrations found were from below the detection limit (DL) to 0.91 ng g^?1 in 2008, DL to 0.38 ng g^?1 in 2009 and DL to 0.59 ng g^?1 in 2010. In general concentrations of organochlorine pesticides were higher in the wet season (3.37 ng g^?1 and 4.79 ng g^?1) than the dry season (1.92 ng g^?1 and 2.71 ng g^?1) for 2009 and 2010, due to control of pests in the pasture and sheds. According to Codex Alimentarius regulations, individual pesticides did not exceed the permissible limits, which for example were 10 μg kg^?1 for alpha hexachlorocyclohexane (HCH) and endosulfan I, 20 μg kg^?1 for p,p’-DDT, and 6 μg kg^?1 for dieldrin, endrin and heptachlor. A reduction of organochlorine pesticide concentrations in cow's milk was noted, indicating that the Mexican government has achieved reduction or elimination of some organochlorine pesticides in response to global agreements on persistent organic pollutants.     

青岛市菜市场垃圾的高温厌氧消化研究

在中试规模下进行菜市场垃圾高温厌氧消化试验,通过监测消化过程中的产气情况和消化液的pH、可溶解性COD(SCOD)、挥发性脂肪酸(VFA)、NH3-N、碱度等变化,确定菜市场垃圾厌氧消化的最大有机负荷,并分析对菜市场垃圾进行高温厌氧消化处理的可行性.结果表明,在中试规模下,菜市场垃圾高温厌氧消化的最高有机负荷可达6.2...     

三峡大坝附近地区反季节蔬菜生产及其产业化战略

三峡大坝附近地区有发展反季节蔬菜生产的小气候环境,有比较丰富的可开垦利用的土地资源,具有广阔的市场。秭归县因地制宜地建设“河谷平坝保护地蔬菜基地”：和“高山反季节蔬菜基地”两大类型反季节蔬菜生产基地,极大地丰富了三峡工程建设区的副食品供应,增加了库区移民的经济收入,取得了很好的经济效益,很大的社会影响和良好的生态效应。     

盐度、C：N对SBR工艺处理海水产品养殖场废水的影响

海水产品养殖场废水中碳、氮的浓度很高,通过序批式反应器（SBR）处理,能有效的降低碳、氮的浓度。在常温（20℃-25℃）条件下,我们检测了不同盐度、C：N下的处理效果,以期实现SBR工艺运行参数的最优化。实验结果表明：盐度为2．5％～3．5％,C：N为10：1的条件下,除碳和生物脱氮的效果最佳。实验验证了SBR工艺在海水产品养殖场废水处理中可以作为一个非常有效的处理手段而应用。     

快速提取用于PCR分析的几种蔬菜DNA的方法

利用两种不同的简便方法提取大白菜、大葱和厚皮酣瓜发芽种子的DNA,均能产生具有重现性的RAPD结果这两种方法提取DNA的PCR扩增结果与多次利用苯酚／氯仿提取DNA的结果一致.RNase处理与否对提取DNA的PCR扩增结果没有影响.方法1不用氯仿,但残留蛋白质等容易造成DNA溶解困难;方法2提取的DNA纯度高对于含蛋白质较少的植物器官或组织,可以选用方法1,而对于含蛋白质较多的植物器官或组织,宜选用方法2.两种方法提取的DNA量与用苯酚／氯仿提取DNA的量相似样品之间提取DNA量的多少主要受研磨破碎程度高低所决定.方法1每人每天提取约120个样品,方法2提取约100个样品,比先前的方法快1倍多.所提取的每个样品DNA约能用于100次PCR反应,两种DNA提取方法简便、迅速,为快速进行大量样品的PCR分析提供了条件.     

生物有机肥料对温室蔬菜硝酸盐和土壤盐分累积的影响

探讨了 3种有机肥料对温室苋菜、芹菜硝酸盐和土壤盐分累积的影响。结果表明 :施用有机肥可显著降低蔬菜硝酸盐含量。用 3种有机肥料处理栽培的芹菜NO3- 含量平均值为 2 133mg/kg ,比用蔬菜专用肥 (对照 )的低 1617mg/kg ,其中施用大三元生物有机肥的芹菜NO3- 值最低 ,为 180 3mg/kg,比对照低 1947mg/kg。施用大三元生物有机肥的土壤盐分 (EC)含量也最低 ,0～ 10cm耕层的盐分为 0 0 79S/m ,比对照低 0 0 2 4S/m ;10～ 2 0cm耕层的盐分为 0 0 5 5S/m ,比对照低 0 0 10S/m。     

动植物油测定方法研究

自配动植物油的四氯化碳溶液.用红外分光光度法进行测定,测定浓度小于配制浓度.测定浓度与配制浓度线性相关性良好.测得相关性方程.在水样测定时,将测定值作为信号值代入线性方程,对测定值进行校正,校正后所得结果更加符合动植物油的实际浓度.     

太湖流域肥料施用策略调整对典型作物系统氮磷流失的影响

太湖流域种植业肥料施用强度普遍较高，且以化学肥料为主要形态.因肥料投入不适宜，种植业氮、磷流失问题显著.2015年以来，各地区积极对种植业肥料施用策略进行调整，但当前工作主要基于粮食作物系统且仍停留在化肥施用总量削减和有机肥施用面积提升层面上，缺少菜地、果园、茶园作物系统的相关数据以及对农业环境问题的响应.对此，以苏州市吴中区为太湖流域典型农区代表，研究2019～2021年稻田、菜地、果园和茶园这4类作物系统肥料策略调整对氮、磷流失的影响.结果表明，肥料源养分投入强度的调控是决定氮、磷流失的关键；适宜的有机肥替代比例有助于降低氮、磷流失风险，但有机肥施用需考虑时机并尽可能搭配农用机械.肥料效率是兼顾农业生产过程环境友好、生产主体经济效益的核心，也是后期肥料施用策略调整的导向.稻田系统的肥料施用策略调整应重视养分中不同元素配比，菜地系统应以种植结构调整为抓手，茶园、果园系统可从复合系统视角制定同时满足茶、果生长的施肥策略，助力构建满足农业绿色发展需求的作物系统.