The 1973 Flood and Man's Constriction of the Mississippi River

The progressive constriction of the Mississippi for navigation since 1837 has caused bottom erosion in some stretches. In others the bottom oscillates up and down with time. The high stages rise much more rapidly. Constriction of the river channel causes flooding and makes floods higher; thus navigation works degrade the protection afforded by levees. The combination of navigation works and levees causes significant rises in the stages of floods. Additional channel constriction and levee building will cause further problems. The 1973 flood's record was man-made.     

农民科技信息获得的渠道

本文采用问卷调查和访谈的方式,调查了北京6个郊区乡镇(村)的农民,研究了农民科技信息获取渠道的现状。结论包括：农民信息获取渠道主要是大众传媒;人际传播中起主要作用的是邻居;农业服务中心和农村远程教育的作用是互补的。     

A decline in lead transport by the Mississippi river

Inputs of pollutant lead to the Gulf of Mexico from the Mississippi River have declined by about 40 percent within the past decade. This decrease has been determined from annual lead loads of the Mississippi River and from the lead record in Mississippi Delta sediments. The observed trend is consistent with reduced consumption of lead in gasoline in the United States. More than 90 percent of the riverborne lead is associated with suspended sediments. Most of this particle-bound lead is deposited within 50 kilometers of the river mouth and is not easily leached at pH values above 3.     

Food safety program. Endrin monitoring in the Mississippi river

Twelve successive monthly samplings and analyses of representative fish and shellfish and of mud and water from the lower Mississippi River showed neither a high concentration of endrin nor a time-ordered change in the concentration. The general absence of endrin from the samples indicated no significant contamination.