降雪对温棚蔬菜的危害及防御

介绍降雪对温棚蔬菜的危害及防御措施.     

ENSO对印度洋偶极子与中国秋季降水关系的影响

利用1950--1999年Hadley中心全球海温资料、NCEP／NCAR再分析资料和中国气象局整编的160站降水资料，通过讨论印度洋偶极子（IOD）独立发生时及IOD与ENSO联合发生时中国秋季降水的差异，研究了ENSO对IOD与中国秋季降水关系的影响。结果表明：仅有IOD发生时，其正位相年使得中国西南地区和黄河流域的秋季降水出现正异常，而当IOD与ENSO伴随出现时，IOD正位相年和E1Nino使得中国西南地区秋季降水正异常区域维持并向东扩展，还使得黄河流域秋季降水转为负异常。此外分析了ENSO改变IOD与中国秋季降水关系的环流成因。     

一次秋季局地强降水过程分析

对常规气象要素、卫星云图和T106物理量诊断产品进行分析,得出2001年10月2～3日发生在桂东南局地强降水成因及中尺度系统特征。     

贵州气温、降水及湿度等气象要素的空间分布特征

利用贵州15个长记录代表站的年、季、月气温。降水及相对湿度资料,进行了EOF分析,结果表明：年、季、月各气象要素第1主分量均显示了各要素的空间变化具有一致性的特点。但各地变化幅度差别较大,年平均气温的空间变化,西部大于东部;季度气温的变化：春季西南部大于东北部,夏季北部较南部大,秋季西部略大于东部,冬季西南部较东北部大。另外,贵州降水的收敛远比气温的收敛慢,反映出影响贵州降水的天气系统较为复杂。贵州降水的空间变化不仅具有一致性的特点,也存在南与北或东与西或局地与全省反相变化的特征。湿度的空间变化特点是冬、春两季西南部变化明显高于东北部,夏季是东北部变化大于西南部,秋季变化是东部高于西部。     

湘江中下游农田土壤和蔬菜的重金属污染

A total of 219 agricultural soil and 48 vegetable samples were collected from the midstream and downstream of the Xiangjiang River（the Hengyang-Changsha section）in Hunan Province.The accumulation characteristics,spatial distribution and potential risk of heavy metals in the agricultural soils and vegetables were depicted.There are higher accumulations of heavy metals such as As,Cd,Cu,Ni,Pb and Zn in agricultural soils,and the contents of Cd（2.44 mg kg^-1 ）,Pb（65.00 mg kg^-1 ）and Zn（144.13 mg kg^-1 ）are 7.97,3.69 and 1.63 times the corresponding background contents in soils of Hunan Province,respectively. 13.2%of As,68.5%of Cd,2.7%of Cu,2.7%of Ni,8.7%of Pb and 15.1%of Zn in soil samples from the investigated sites exceeded the maximum allowable heavy metal contents in the China Environmental Quality Standard for Soils（GB15618-1995,Grade Ⅱ）.The pollution characteristics of multi-metals in soils are mainly due to Cd.The contents of As,Cd,Cu,Pb and Zn in vegetable soils are significantly higher than the contents in paddy soils.95.8%, 68.8%,10.4%and 95.8%of vegetable samples exceeded the Maximum Levels of Contaminants in Foods（GB2762-2005）for As,Cd,Ni and Pb concentrations,respectively.There are significantly positive correlations between the concentrations of Cd,Pb and Zn in vegetables and the concentrations in the corresponding vegetable soils（p〈0.01）.It is very necessary to focus on the potential risk of heavy metals for food safety and human health in agricultural soils and vegetables in the midstream and downstream of the Xiangjiang River,Hunan Province of China.     

声画并茂 相褥益彰——地理录像教学实验报告

从1991年秋季起．我尝试在高一两个班分别采用录像形式和传统方法进行地理课堂教学的实验。实验证明，地理录像教学深受学生欢迎．教学效果显著，发展前景广阔。