长期施肥下浙江稻田不同颗粒组分有机碳的稳定特征

依托浙江水网地区稻田长期定位施肥试验(1996~2013年),利用固态13C核磁共振波谱技术,研究长期不同施肥措施下土壤各颗粒组分有机碳含量及其化学结构特征.结果表明,与不施肥对照(CK)相比,秸秆与化肥配施(NPKRS)、栏肥与化肥配施(NPKOM)、单施化肥(NPK)和单施栏肥(OM)处理均显著(P0.05)增加了砂粒(2~0.02 mm)、粉粒(0.02~0.002mm)和黏粒(0.002 mm)组分中有机碳含量;而单施秸秆(RS)处理仅显著增加砂粒组分有机碳含量.此外,与单施化肥处理相比,有机肥和化肥配施促进了新增有机碳在粉粒和黏粒组分的分配,更有利于新增有机碳的稳定.应用13C-NMR波谱技术进行结构表征,结果表明粉粒和黏粒组分有机碳的化学结构存在明显差异,粉粒组分烷氧碳、芳香碳的相对含量高于黏粒,而烷基碳、羰基碳的相对含量低于黏粒.长期有机肥与化肥配施下粉粒和黏粒烷基碳相对含量较单施有机肥处理分别降低9.1%~11.9%和13.7%~19.9%,烷氧碳的相对含量则分别增加2.9%~6.3%和13.4%~22.1%,表明有机肥与化肥配施处理降低了粉粒和黏粒组分有机碳的分解程度.长期单施化肥处理下粉粒和黏粒组分有机质的芳化度和疏水性低于单施有机肥处理和不施肥处理,有机质的矿化稳定性较低.长期有机肥与化肥配施,尤其是NPKOM处理,通过增加化学抗性化合物和碳水化合物的积累,并且减缓活性组分的分解提高粉粒和黏粒组分有机碳含量,是促进稻田土壤有机碳可持续积累的有效措施.     

华北平原玉米-小麦轮作农田N2O交换通量的研究

以华北地区冬小麦-夏玉米轮作农田为研究对象,运用静态箱法对正常施肥及正常施肥结合秸秆还田农田N2O交换通量进行了连续1 a对比研究.正常施肥及正常施肥结合秸秆还田样地N2O全年的累积排放量分别为7.61 kg.hm-2和12.6kg.hm-2,其中秸秆还田引起N2O排放明显增加主要发生在玉米生长季节.两种处理样地在玉米季N2O的排放量占全年累积排放的57%～86%,表明华北玉米-小麦轮作体系中N2O排放主要集中在玉米季.各次施肥后10 d内N2O的累积排放量约占全年总排放量的71%～88%,显然现有化肥极大促进了华北农田N2O排放.     

Barriers to the adoption of proactive environmental strategies

This study contributes to the knowledge of the difficulties or barriers found by firms when adopting proactive environmental strategies, providing empirical evidence from 240 Spanish industrial firms. A set of 25 barriers are initially evaluated by the managers of the sample firms and are grouped into four types of difficulties facing firms: external barriers, endemic limitations of the firm, limited environmental motivation and limited preparation of employees and operational inertia. The estimation of a structural equation model leads us to conclude that only the barriers identified as endemic limitations of the firm can be characterized as “effective barriers”, defined as problems preventing firms from progressing toward proactive environmental behavior.     

鄱阳湖生态区长期施肥对稻田土壤碳汇效应与固碳潜力的影响

在施肥条件下确定平衡状态时,土壤有机碳含量水平对于正确评价土壤的固碳潜力和制定合理的有机物质分配措施具有重要意义。分析了前人研究的江西省有机碳储量数据并采用Jenny模型对长期不同施肥下有机碳动态数据进行模拟。结果表明,鄱阳湖生态区有机碳储量占全省的46%,以鹰潭地区最高,九江地区最低。施肥明显增强了土壤的碳汇作用,单施有机肥或有机无机肥配施（70F+30M、50F+50M、30F+70M、NPKM、NPK+S、NPK+P和NPK+C）处理的土壤有机碳含量明显高于施化肥处理,以南昌县的30F+70M、进贤县的NPKM和余江县的NPK+P处理最高,其平衡时有机碳含量和固碳潜力分别较施化肥处理提高了3061%和6115%、3017%和5496%、3826%和7479%。因此,提高鄱阳湖生态区农田有机碳密度和固碳潜力最有效方法是有机无机肥配施,其配施方式以猪粪配施化肥相对最好,配施比例以70%有机肥配施30%化肥为宜     

西昌高原鳅人工繁殖技术研究

对西昌高原鳅(Triplophysa xichangensis)人工繁殖中的催产药物及其剂量、受精方式、孵化方法和仔鱼水花培育方法等一系列关键技术进行了详细研究。结果表明,对性腺发育至Ⅳ+~Ⅳ++期的雌鱼分二次注射LRH-A2 0.1μg/g(鱼体重)和HCG 20 IU/g(鱼体重),雄鱼剂量减半,注射量0.1 mL,能很好地促进雌雄鱼发情并产卵排精,在水温19±0.5℃时的效应时间为30.5~31 h;在一个特制的塑料盆中完成了亲鱼培育、打针催产、发情、自然产卵受精、孵化以及仔鱼培育等全部人工繁殖过程,受精率、孵化率和仔鱼水花培育20 d的成活率平均分别为97.2%、85%和85%。本研究成果可应用于西昌高原鳅规模化繁育,对长江上游鱼类生物多样性保护有着积极意义。     

施肥与秸秆还田对太湖稻-油复种系统春季杂草群落特征的影响

掌握不同管理模式下稻田杂草群落特征,可以为杂草综合防治及农田生物多样性的保持提供理论依据和技术途径。借助稻-油复种系统长期定位施肥试验（江苏吴江,始于1987年）,于2007年春季监测长期不同施肥和秸秆还田对农田杂草群落的影响。施肥与秸秆还田对春季稻田杂草群落结构特征存在显著作用。长期有机无机肥配合施用下（化肥+猪粪+秸秆）杂草生物多样性和生物量均下降;长期不施氮肥下杂草总密度显著增高,达1 810 ind./m2;长期不施肥时,田间野老鹳草成为优势种群,其相对密度达879%;全年秸秆还田（化肥+油菜秸秆+水稻秸秆）下,田间优势杂草种群为禾本科的看麦娘,其相对密度达697%;秋熟水稻秸秆还田下杂草生物量下降,而生物多样性显著提高。上述结果表明,通过合理施肥和秸秆还田措施,可以对稻油复种模式中春季杂草群落进行有效调控。     

2,2’,4,4’-和3,3’,4,4’-四氯联苯(TCB)对小白鼠体外受精的影响(英文)

采用体外受精技术评价环境污染物 2 ,2’ ,4,4’ 和 3,3’ ,4,4’ 四氯联苯对小白鼠卵母细胞受精能力和 2 细胞胚胎发育的毒性作用 .实验结果表明 :ρ(PCB) =0 .1,1.0 ,10 .0mg/mL的 2 ,2’ ,4,4’ 和 3,3’ ,4,4’ 四氯联苯均显著降低小白鼠卵母细胞的受精能力 ;ρ(PCB) =1.0 ,10 .0mg/mL的 2 ,2’ ,4,4’ 和 3,3’ ,4,4’ 四氯联苯使卵母细胞的退化率和 2 细胞的畸形率显著增加 ;两种四氯联苯对小白鼠卵母细胞体外受精能力、退化率和 2 细胞胚胎的畸形率无统计差异 .表 2参 2 5     

EFFECTS OF FOREST FERTILIZATION ON STREAM WATER CHEMISTRY IN THE APPALACHIANS1

ABSTRACT: Stream water chemistry was monitored on two watersheds on the Fernow Experimental Forest in north-central West Virginia to determine the effects of forest fertilization on annual nutrient exports. Ammonium nitrate and triple superphosphate were applied simultaneously at rates of 336 kg ha^?1 N and 224 kg ha^?1 P₂O₅, respectively, which are similar to rates used in commercial forest operations. The treatment significantly increased outputs of several ions. Annual outputs of nitrate N increased as much as 18 times over pretreatment levels, and calcium and magnesium increased as much as three times over pretreatment levels the first year after fertilization. Outputs for these nutrients were elevated for all three post-treatment years. Although nitrate N increased significantly, only about 20 percent of the applied fertilizer was accounted for in stream water exports. Outputs of phosphate P declined following fertilization, probably because the watersheds are phosphorus deficient, but by the third year, they slightly exceeded predicted values. Estimated nutrient losses to deep seepage were substantial, especially on the leakier south-facing catchmeat, on which some nutrient losses were equal to or greater than those in stream water. When the nutrient exports associated with both stream discharge and ground water recharge were combined, the percentages of applied N that were lost were similar on the two watersheds, averaging 27.5 percent. Less than 1 percent of the applied P was lost from either watershed in the combination of streamflow and deep seepage.     

External threats to ecosystems of US national parks

Activities beyond national park boundaries are now the principal source of threats to park natural resource integrity. Assessing the full impact of major threats as air and water pollution requires a long-term ecosystem-level approach in research design and execution, and park management. Failure to take such an approach renders most existing park data bases useless in the documentation of external threats. While the concept of managing national parks as ecosystems is not new, Park Service research and its organization have not provided the information necessary for such a basis of management. Quantifying the impacts on park resources due to external hydrologic regulation and air pollution is a good example of the need to employ an ecosystem approach in research. However, implementing such a program will require a fundamental change in research administration, priority setting, and conceptual approach.The first four of the articles in this special section arise from an AAAS symposium onExternal Threats to Ecosystems of the National Parks in the USA, which was convened in 1982. The articles have been revised to reflect subsequent developments in this field. The first article, by Dr. Stottlemyer, the symposium organizer, serves as an introduction to the topic. The fifth article in this special section was submitted separately, but included because it also is related to this particular topic.