Nitrogen-fixing bacteria in soil can convert excess nitrogen into which can contaminate groundwater.
a/an forms around a well when the water table begins to slope toward the well.
the water in an artesian well comes from a/an aquifer.
a well not only has to reach the but also has to go deeper.
in most aquifers, the materials that make up the aquifer are relatively which means they aren't chemically reactive.
aquifers are more prone to pollution.
the two primary components of a septic system are a septic tank and a/an
groundwater that comes to the surface naturally is known as a/an

Reading graphs: unemployment us unemployment rate (1961-2011) identify the trends in the graph and then use the drop- down menu to complete each statement from 1961 to 1965 unemployment was in the mid-2000s through 2011. unemployment was percentage unemployed 1961 1971 1981 1991 2001 2011 year

Which type of seismic waves are confined at the surface

Scientist: cross-sections of stalactites—calcite formations deposited on cave ceilings by seeping water—can reveal annual variations in rainfall in particular areas over hundreds and thousands of years. we often found that when—according to these cross-sections—drought occurred in a particular area, it coincided with the collapse of an ancient society in that area. i hypothesize that drought reduced agricultural productivity in these areas, thereby leaving these societies without the resources needed to handle internal stresses and external threats. which of the following, if true, would most weaken the support for the scientist's hypothesis? a. many droughts indicated in the cross-sections of stalactites do not correspond with the collapse of a society in that area. b. information from the cross-sections of stalactites alone cannot reveal the level of agricultural output in an area at a particular time. c. most of the societies that collapsed during droughts did so when internal power struggles coincided with military raids from neighboring societies. d. most of the societies that collapsed during droughts maintained large stockpiles of food and water at the time of their collapse. e. information from stalactites also suggests that the collapse of some societies coincided with periods of abnormally high rainfall.