黄土高原水土保持对农业持续发展的作用

通过大量事实分析了水土流失的危害及水土保持对农业可持续发展的作用,充分说明了水土保持是黄土高原农业走持续发展道路的可靠保证,也是改善生态环境和生产条件并防止山区水旱灾害,促进群众脱贫致富的根本途径。     

刍议黄河下游引黄泥沙治理及发展趋势

在总结分析黄河下游引黄灌区近40年来泥沙处理的主要方针和泥沙公布状况的基础上,客观评价了当前及今后灌区泥沙治理环境,分析了黄河下游引黄灌区泥沙治理及分布的主要发展趋势。认为在渠首自流集中沉沙的优越条件日渐丧失的条件下,今后引黄泥沙将主要采取浑水灌溉,远距离输沙及分散沉沙的处理方式,黄河下游悬河的现状及古黄河冲积区洼地的存在为这种处理方式提供了前提。提出了结合黄河大堤淤背处理引黄泥沙的设想,开阔了泥沙治理的视野。     

广东省典型区域农业土壤中重金属污染空间差异及原因分析

分析了广东东翼(汕头)、西翼(湛江)和珠江三角洲(东莞、惠州、中山和顺德)等典型区域农业土壤中8种重金属(Cu、Zn、Ni、Cr、Pb、Cd、As和Hg)元素的含量。结果表明,578个农业土壤表层样中,有230个样品的重金属含量超过国家土壤环境质量二级标准值,超标率39.79%,Pb没有超标,Ni超标最严重;果园土比水稻土、菜园土污染严重;不同区域的土壤污染程度是珠江三角洲>东翼(汕头)>西翼(湛江),珠江三角洲的西、北江流域(中山、顺德)土壤重金属污染程度要比东江流域(东莞、惠州)严重。人为因素、成土母质和不同流域水质差异是造成广东典型区域农业土壤重金属污染的原因。     

中国北方典型地区农用地膜污染现状调查及其防治对策

通过对我国北方典型地区的调查，初步探索了该地区土壤农膜残留量和残膜特征。研究表明，河北省典型地区温室大棚、蔬菜田和作物田的农膜土壤残留量平均分别为5.629、7.369和2.822 kg·hm^-2，黑龙江省典型地区温室大棚、蔬菜田和作物田残留量平均分别为4.169、3.682和2.430 kg·hm^-2，各采样点之间存在着较大差异，但普遍较高，均明显高于未使用农膜的对照土壤。两地区之间除作物田的土壤农膜残留量没有明显差异外，河北地区其他两类土壤中的农膜残留量水平明显高于黑龙江地区，这种差异与各地区在农事活动及农膜使用上的差异具有一定的相关性。上述两地区土壤中残留农膜尺寸基本一致，主要集中在10～15 cm之间。该文针对我国目前农膜使用情况及其污染现状，提出了相应的防治对策。     

Impacts of lost fishing gear on coral reef sessile invertebrates in the Florida Keys National Marine Sanctuary

The Florida Keys coral reef ecosystem supports multimillion-dollar commercial and recreational fisheries. The ecological effects caused by fishing gear that is lost when cut or broken after snagging on the bottom is a growing concern to managers and scientists. Few data exist, however, to assess the impacts of lost fishing gear to benthic organisms and habitat structure. In this study, 63 offshore coral reef and hard-bottom sites were surveyed during 2001 to quantify the impacts of lost fishing gear to coral reef sessile invertebrates. Lost hook-and-line fishing gear accounted for 87% of all debris (N=298 incidences) encountered and was responsible for 84% of the 321 documented impacts to sponges and benthic cnidarians, predominantly consisting of tissue abrasion causing partial individual or colony mortality. Branching gorgonians (Octocorallia) were the most frequently affected (56%), followed by milleporid hydrocorals (19%) and sponges (13%). Factors affecting the impacts of lost fishing gear include sessile invertebrate density, the density of lost fishing gear, and gear length. While lost hook-and-line fishing gear is ubiquitous in the Florida Keys, less than 0.2% of the available milleporid hydrocorals, stony corals, and gorgonians in the habitats studied are adversely affected in terms of colony abrasions and partial mortality.     

Finding a needle in the haystack: Regional analysis of suitable Eld’s deer (Cervus eldi) forest in Southeast Asia

For species whose decline preceded the modern era and whose distribution is in the developing world, it is difficult to map suitable habitat across its former range. Eld’s deer (Cervus eldi) is an endangered cervid whose range across Southeast Asia was reduced during the last century to disjoint populations in Myanmar and Cambodia. We used ecological data from the present populations to determine landscape and habitat parameters that would help us predict the occurrence of the species in forests not yet surveyed. The suitable-forest GIS model was created using four readily available datasets for elevation, forest type, canopy closure, and human density. Comparison of the GIS model with 24 verified sightings of Eld’s deer during recent large mammal surveys in Cambodia, found 22 sightings (92%) within predicted suitable forest. Use the suitable-forest GIS model to survey a province in southern Lao People’s Democratic Republic, located a single, previously unreported population from 9 patches surveyed. In a separate analysis, a logistic regression model to predict Eld’s deer habitat in Northern Cambodia found percent tree cover, presence of wetlands, and distance to villages as the best predictors of deer, similar to variables used in the GIS model, with the exception of the importance of wetlands. Using mean annual rainfall to rank suitable-forest patches identified in the GIS model indicated dry dipterocarp forests in Northeastern Cambodia and Northern Myanmar have the highest potential to conserve eld’s deer. Examination of the suitable-forest GIS map and current protected areas indicated only Cambodia, with 11% suitable forest protected, has placed sufficient dry dipterocarp forest under protected status. Other Southeast Asia countries have not recognized dry dipterocarp forest as a significant ecotype worthy of conservation status.     

基于粗集权重的改进可拓评价方法在灌区干旱评价中的应用

在分析了灌区干旱评价特点和目前评价方法不足的基础上，引入了基于非对称贴近度和粗集理论的改进可拓评价方法，有效避免了灌区干旱评价指标界限的纲性量化导致的遗漏问题和单项指标评价结果的矛盾性、不确定性和不相容性。与传统可拓评价方法相比，在指标权重的确定中采用经验因子协调主客观权重，克服了以往决策者过分依赖专家经验知识确定的不足。在等级评价中采用非对称贴近度原则，代替最大隶属度，有效解决最大隶属度原则的失效问题。计算实例表明，采用基于粗集权重的改进可拓评价方法进行灌区干旱评价是切实可行的。     

新沂市丘陵山区雨水集蓄利用灌溉调度优化研究

雨水集蓄利用是近年来缺水型山丘区补充水源的有效措施之一,成为促进当地农业经济发展和农民脱贫致富奔小康的根本途径,其理论研究尚需进一步探讨和完善.该文结合新沂市山丘区雨水集蓄利用规划的实例,采用自优化模拟模型对其雨水利用灌溉调度进行了优化研究,达到了预期目的,实现了丘陵山区雨水集蓄利用灌溉系统的优化调度过程.     

中国北方典型地区农用地膜污染现状调查及其防治对策

通过对我国北方典型地区的调查,初步探索了该地区土壤农膜残留量和残膜特征.研究表明,河北省典型地区温室大棚、蔬菜田和作物田的农膜土壤残留量平均分别为5.629、7.369和2.822 kg·hm-2,黑龙江省典型地区温室大棚、蔬菜田和作物田残留量平均分别为4.169、3.682和2.430 kg·hm-2,各采样点之间存在着较大差异,但普遍较高,均明显高于未使用农膜的对照土壤.两地区之间除作物田的土壤农膜残留量没有明显差异外,河北地区其他两类土壤中的农膜残留量水平明显高于黑龙江地区,这种差异与各地区在农事活动及农膜使用上的差异具有一定的相关性.上述两地区土壤中残留农膜尺寸基本一致,主要集中在10～15 cm之间.该文针对我国目前农膜使用情况及其污染现状,提出了相应的防治对策.     

北京市平原农区深层地下水硝态氮污染状况研究

对北京市平原农区481眼深层井硝态氮含量进行了分析。结果表明,北京市平原农区深层地下水硝态氮(NO-3N)含量平均为5.74mgL-1,其中48.4%的调查机井受到人类活动的影响(NO-3N≥2mgL-1),21.0%的机井超过国际安全允许上限(NO-3N≥10mgL-1),8.1%的机井超过我国饮用水上限(NO-3N≥20mgL-1)。地下水位在120～200m的饮用水质量总体较好,硝态氮平均含量为5.16mgL-1,超标率为13.8%;而地下水位在70～100m的农灌水质量相对较差,硝态氮平均含量为5.98mgL-1,超标率为24.1%。近郊地下水质量劣于远郊,其中近郊饮用水超标率为38.7%,远郊为3.0%;近郊农灌水超标率为52.6%,远郊为15.3%。地下水硝态氮超标区域主要集中在老菜区。总体来看,北京市平原农区地下水硝态氮污染程度已超过欧美国家,必需及早采取有效措施加以控制。