珠三角主要工业区周边蔬菜产地土壤重金属污染调查分析

采集珠三角地区主要工业区周边蔬菜产地土壤,研究土壤中铅(Pb)、镉(Cd)、汞(Hg)、砷(As)、铬(Cr)5种重金属的含量与分布特征。参照国家土壤环境质量标准(GB15618-1995)中的二级标准,采用单项污染指数法和综合污染指数法,对其重金属污染现状进行评价。结果表明:232份土壤样品中,Cd、Hg、As、Cr的超标率分别为45.06%、7.73%、5.15%和1.29%,未见Pb超标;37.34%的土壤受到不同程度的污染,Cd污染情况最为严重,Hg污染次之;土壤污染以单一重金属污染为主,未出现3种及以上重金属复合污染。各地污染状况呈现区域差异,东莞地区受污染的样品比例较大,珠海和广州的污染情况相对较轻。该区域的土壤重金属污染形势不容乐观,其可能给农业生产带来的风险应引起重视。     

干旱区绿洲土壤盐渍化动态变化及其影响因子分析研究—以渭干河-库车河三角洲绿洲为例

[目的]土地盐渍化是干旱、半干旱地区由于人类不合理的开发土地资源活动和脆弱的生态环境相互影响而引起的土地退化问题,它严重威胁着干旱区绿洲生态环境的稳定性,约束着社会经济的可持续发展.因此,监测盐渍地的分布范围及其盐渍化程度,分析其成因对绿洲生态环境和社会经济可持续发展有着重要的意义.[方法]以塔里木盆地北缘盐渍地普遍发育区域渭干河-库车河三角洲绿洲为例,利用 1989年TM,2001年ETM +和2007年ALOS 3个时期的遥感影像数据,在野外调查的基础上,采用监督分类方法,进行了盐渍地动态变化分析研究.[结果]1989～2007年的19 a中,重度盐渍地面积从1 177.78 km2增加到1 192.33 km2,中度盐渍地面积增加了1 353.25 km2,轻度盐渍地面积减少了3.40;,总盐渍地面积呈增加趋势,增加面积为981.30 km2.[结论]盐渍化影响因子中人为因素占主导地位.对水和土地资源需求的增加以及不合理利用导致了该区域生态环境的恶化,进一步加重了盐渍化问题.     

珠江三角洲主要城市郊区公路两侧土壤和蔬菜中铅含量初探

采用原子吸收分光光度法,对珠江三角洲主要城市中山、佛山、深圳市郊公路两侧的土壤和蔬菜中的重金属铅含量进行了测定,并分析了土壤和蔬菜中的铅污染程度和分布规律结果表明:随距离增大,土壤和蔬菜中的铅含量逐渐降低     

CONCENTRATIONS AND FLUXES OF DISSOLVED NUTRIENTS IN THE YANGTZE RIVER: LONG-TERM TRENDS AND ECOLOGICAL IMPACTS

• Historic trends in nutrient loading and flux in the Yangtze River were analyzed• Decreasing trends in the concentrations and fluxes of DSi were found• Significant increasing trends in DIN and DIP concentrations were observed• The frequency of and area covered by red tide outbreaks substantially increased• Atmospheric deposition become a vital factor influencing DIN loadings and fluxesIntensifying human activity in the Yangtze River basin has substantially increased nutrient concentrations in the Yangtze River Estuary, leading to degradation of the coastal environment. Analysis of nutrient determinations published over the past 50 years reveals a gradual decreasing trend in the concentrations and fluxes of dissolved silicate (DSi). However, both dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphate (DIP) concentrations have increased significantly since the 1970s. The frequency of and area covered by red tide outbreaks have increased greatly during this period, mainly due to changes in nutrient supply ratios [i.e., N/P (DIN/DIP), N/Si (DIN/DSi), P/Si (DIP/DSi)]. A strong correlation was found between the riverine DIN fluxes and the estimated DIN inputs from the major N sources, particularly fertilizers and atmospheric deposition. The data provide a comprehensive assessment of nutrients in the Yangtze River basin and their ecological impacts and indicate a potentially significant influence of atmospheric deposition on DIN loadings and fluxes.     

黄河三角洲自然保护区鹤类南迁迁徙规律初步研究

黄河三角洲国家级自然保护区是鹤类重要的迁徙中转站,在鹤类保护中具有重要意义。在中国9种鹤类资源中,保护区有7种。2006年鹤类南迁期,作者于10月初至12月初,采用定点观察法,对保护区内的鹤类进行观察,并对鹤类南迁的迁徙规律进行分析。     

Thymoma‐associated lymphocytosis in a dog

A 9‐year‐old female spayed English Springer Spaniel was evaluated for a cranial mediastinal mass and lymphocytosis. Flow cytometric immunophenotyping of peripheral blood lymphocytes revealed 97% as CD3 positive, confirming a T‐cell lineage. Additionally, T‐cell subset assessment showed 53.2% to be double‐negative T‐lymphocytes, expressing neither CD4 nor CD8 surface markers. The number of double‐negative lymphocytes in circulation coincided with the number of T‐cell receptor (TCR) γδ‐expressing T‐cells in circulation. Molecular T‐cell clonality analysis of TCR Gamma (TCRG) gene rearrangement showed a polyclonal expansion of T‐lymphocytes. Histopathology confirmed the mass to be a thymoma, supporting the diagnosis of thymoma‐associated T‐cell lymphocytosis. Resolution of the lymphocytosis after removal of the thymoma provided further evidence for this diagnosis. To the authors' knowledge, this case is only the second report of thymoma‐associated peripheral lymphocytosis in the veterinary literature, and is the first to report a confirmed thymoma‐associated peripheral γδ T‐cell lymphocytosis in a dog.     

玻色子表面δ相互作用研究sdgIBM1核谱

用ｓｄｇＩＢＭ１的组态混合波函数和玻色子表面δ相互作用研究三玻色子核的能谱，理论计算结果令人满意，能拟合比ｓｄｇＩＢＭ１多得多的能级，误差还更小，说明ｇ玻色子起着重要的作用，进一步证明这种模型是成功的。     

黄河三角洲盐渍土可持续利用对策

分析了黄河三角洲盐渍土可持续利用的限制性因素,并提出黄河三角洲盐渍土可持续利用的对策。盐渍土可持续利用的限制性因素为:淡水资源不足、土壤肥力低、土壤盐分含量偏高和生态环境脆弱。黄河三角洲盐渍土可持续利用的对策是:完善农田水利基本建设;采取水利工程措施、农业生产技术和生物措施,综合治理盐渍土;加强盐渍土综合利用的基础理论、技术方法研究;根据生态农业理论,统筹规划,用地与养地相结合,合理配置盐渍土的农、林、牧比例;完善盐渍土开发利用的政策法规。     

The use of nitrogen-15 natural abundance and nitrogen yield of non-nodulating isolines to estimate nitrogen fixation by soybeans (Glycine max L.) across three elevations

Summary Dissimilarities in soil N uptake between N₂-fixing and reference non-N₂-fixing plants can lead to inaccurate N₂ fixation estimates by N difference and ¹⁵N enrichment methods. The natural ¹⁵N abundance ( ¹⁵N) method relies on a stabilized soil ¹⁵N pool and may provide reliable estimates of N₂ fixation. Estimates based on the ¹⁵N and differences in N yield of nodulating and non-nodulating isolines of soybean were compared in this study. Five soybeans from maturity groups 00, IV, VI, and VIII and their respective non-nodulating isolines were grown at three elevations differing in ambient temperature and soil N availability. Despite large differences in phenological development and N yield between the non-nodulating isolines, the ¹⁵N values measured on seeds were relatively constant within a site. The ¹⁵N method consistently produced lower N₂ fixation estimates than the N difference method, but only in three of the 15 observations did they differ significantly. The average crop N derived from N₂ fixation across sites and maturity groups was 81% by N difference compared to 71% by ¹⁵N. The magnitude of difference between the two methods increased with increasing proportions of N derived from N₂ fixation. These differences between the two methods were not related to differences in total N across sites or genotypes. The low N₂ fixation estimates based on ¹⁵N might indicate that the nodulating isolines had assimilated more soil N than the non-nodulating ones. A lower variance indicated that the estimates by N difference using non-nodulating isolines were more precise than those by ¹⁵N. Since the differences between the estimates were large only at high N₂ fixation levels (low soil N availability), either method may be used in most situations when a non-nodulating isoline is used as the reference plant. The ¹⁵N method may have a comparative advantage over N difference and ¹⁵N enrichment methods in the absence of a suitable non-N₂-fixing reference plant such as a non-nodulating isoline.     

社会经济发展对珠江三角洲基塘系统的影响

在深入了解珠江三角洲基塘系统的发展历史及实地调查研究典型基塘系统的基础上，就现阶段社会经济发展对珠江三角液基塘系统的影响进行了详细的分析，结果发现，精养模式大量发展，重渔塘养殖，轻基面种植，基面畜禽养殖业下降，传统基塘系统良性循环的格局被打破，近两年特种鱼的经济效益下降，渔塘水质受污染，出现新型的集约化基塘系统，据此对基塘系统的发展提出了5个方面的对策。