不同品种大白菜对镉的吸收积累差异

通过盆栽试验,研究了30个大白菜品种在受不同程度镉(Cd)污染的土壤中吸收和积累镉能力的差异.结果表明:a.在土壤镉浓度为0.6mg.kg-1时,白菜Cd含量超标率为23.33%,而在土壤镉浓度为1.2mg.kg-1时超标率达46.67%,表明大白菜容易受到Cd污染.b.以大白菜地上部分的镉含量、不同土壤中白菜镉含量的递增率及生物量变化率为指标,研究得出四季王春白菜、丰研夏帅、改良夏帅、玉丰55白菜、多抗四号和丰抗70为镉低积累品种,可在镉轻度污染土壤中推广种植.     

垫江牡丹主产区土壤重金属含量的分析与评价

采用环境调查的方法研究垫江牡丹主产区土壤6种重金属含量状况,依据相关标准,应用单项污染指数法和综合污染指数法进行评价,以便为牡丹GAP基地的建设提供科学参考．结果表明：该区土壤的各种污染物的单项污染指数均小于1,表明土壤无超标污染物;该区5．3％的土壤污染物综合污染指数大于0．7,小于1,处于警戒级．其余94．7％的综合污染指数均小于0．7,表明土壤质量良好,为清洁水平,符合绿色药材栽培的环境质量要求．     

油气生产建设对水土流失的影响及防治

针对油气生产水土流失问题,采用归纳分析的方法,分析了油气生产建设的不同阶段呈现的不同特点,不同阶段水土流失的影响差别较大,其中勘探对水土流失的影响较小,油田地面工程和管道工程建设对水土流失的影响大,开采对水土流失影响有限,长输管道运营对水土流失基本没有影响.油气企业通过加大资金投入、制定防治技术规范、明确防治责任、加强管理等防治措施,取得了较好的防治效果.     

山西黄土CBR与E0的相互关系式的修订

在山西省选取4条高速公路,每条公路上选取一段黄土路基试验段,开展现场回弹模量E0和承载比CBR试验,对回弹模量和CBR之间的相互关系进行了研究,对已有的相互关系式提出修正和补充,提出山西晋北和晋南黄土路基回弹模量和承载比CBR之间的换算关系,为山西黄土地区路面结构的设计提供参考依据。     

道路建设中的耕地占用问题及其对策初探

结合我国耕地资源面临的严峻形势与道路建设迅速发展的实际 ,从道路建设对耕地资源的直接占用 ,道路施工产生的新的水土流失对耕地资源的危害影响等方面分析道路建设占用耕地的特点与建设中存在的问题 ,从道路建设的设计、选线、施工等工程技术角度初步对解决该问题的对策进行了探讨     

防治土壤重金属污染面临的主要问题及法律规制

近几年新闻媒体曝光了“毒大米”、“血铅超标”等一批土壤重金属污染致害事件。我国在土壤重金属污染防治工作中,长期以来没有重视土壤重金属污染的特性以及针对这些特性制定相应的法律规范,因此,现如今面临两大困扰：一是历史遗留问题全面爆发;二是缺乏相应法律规制。可以通过借鉴美国“超级基金”制度来建设我国自己的“超级基金”以解决受污染土地的治理问题,同时转变立法导向,重新制定符合重金属污染特征的环境保护标准以实现对土壤重金属污染的规制。     

农业土壤污染防治的法律法规分析

农为民本,农业土壤污染直接关系着粮食安全,目前我国对于土壤污染并无专门的防治法律出台,而农业土壤污染仅靠《农业法》等几部法律有零星规定远远不够,在执法环节更是问题重重。本文分析相关法律及其不足之处,并提出合理化建议。     

利用脱硫石膏改造盐碱地的循环经济模式

利用燃煤电厂脱硫石膏改良盐碱地对于确保国家粮食安全和生态安全,发展循环经济具有重要意义,已经引起国内外的广泛关注.选择具有典型代表性的白城市盐碱化土壤,采用田间试验进行施用脱硫石膏改良碱化土壤的效果研究.研究表明施用脱硫石膏,对降低土壤碱化度和pH值,提高农作物出苗率和产量有明显效果.利用电厂脱硫石膏改造盐碱地,是将工业污染排放物组织成一个"资源-产品-再生资源"的模式.     

Short- and long-term effects of site factors on net N-mineralization and nitrification rates along an urban-rural gradient

Long- and short-term effects of urban site factors on net N-mineralization and nitrification rates were investigated in oak stands along an urban-rural land-use transect in the New York City metropolitan area. We used reciprocal transplants of undisturbed soil cores between urban and rural forests to determine the relative importance of long-term effects (mor vs. mull soils, quality of soil organic matter, and deposition of N) vs. short-term effects (soil temperature) of urban factors in controlling field N-transformation rates along the gradient. In addition, undisturbed soil cores from surface (A, Oe horizons) and subsurface (B horizon) soil were collected from urban, suburban, and rural stands and allowed to incubate in these respective sites to compare the net effect of all urban factors with transplanted-core results. The transplant experiment revealed that soil type (long-term) affected net N-mineralization and nitrification rates. Urban soils nitrified nearly 6.3 and 5.4 times more than rural soils incubating in urban and rural stands, respectively (p = 0.003 and p = 0.002, respectively). Similarly, in rural stands total accumulation of inorganic N was 87% higher in urban than in rural soils, whereas in urban stands, urban soils mineralized 83% more N than rural soils (p = 0.043 and 0.08, respectively). Comparing soils incubating in their native locations, urban soils incubating in urban stands mineralized more than 2.5 times the amount of N than rural soils incubating in the rural stands (p = 0.019). By contrast, urban soils incubating in urban stands exhibited a 8-fold increase in nitrification over rural soils incubating in rural stands (p = 0.008). As with the transplanted cores, the urban and suburban environments had a positive effect on net rates of N-mineralization and nitrification in both surface and subsurface layers of soil. The surface layer of suburban and urban stands had a 3- and 2.3-fold higher accumulation of net inorganic N than rural stands (ANOVA, p = 0.05). Similarly, in the subsurface layer both urban and suburban stands had 2.6-fold higher net N-mineralization rate than rural stands (ANOVA, p = 0.01). Along this urban-rural gradient, soils in oak stands exhibit higher net nitrification and, to a lesser extent, net N-mineralization rates in urban and suburban stands than in rural stands. Results from the transplant experiment and in situ measurements of surface and subsurface soil indicate that long-term effects (mor vs. mull soils, N deposition) contribute to the higher N-transformation rates in urban and suburban stands. As a result of these effects, urban and suburban stands have the potential for higher losses of N than rural stands.     

从唐人小说看传统文化中的土地崇拜情结

土地崇拜,是民族文化心理中最具活力的原型之一.它对于唐人小说的商贾题材创作,有着深刻的影响,直接导致了作品对于商贾带有强烈贬抑色彩的描写.这一现象实质上反映了传统的农本文化在商业大潮中所面临的价值信仰危机.农本文化的价值信仰在这类作品中,往往借助非现实的志怪形式,来完成其神圣化、宗教化的过程。