Based on the scenario you provided regarding atrazine concentrations in groundwater near the Platte River, the following patterns can be observed from the responses given:
B. Atrazine concentrations in groundwater were highest during July and early August. - This response likely correlates with seasonal agricultural practices and herbicide application patterns, suggesting that atrazine levels could be affected by the timing of its use.
C. Atrazine in the river water can contaminate groundwater great distances from the original source of the herbicide. - This response supports the hypothesis that groundwater withdrawals may draw in contaminated river water, showing that the contamination can spread.
D. Atrazine was present in groundwater throughout the year, regardless of the distance from the river. - This indicates a persistent presence of atrazine in groundwater, suggesting that once introduced, it can remain detectable over time.
In summary, choices B, C, and D reflect observed patterns regarding the behavior and persistence of atrazine in the groundwater as influenced by seasonal changes, contamination sources, and distribution through the aquifer.