Comparison of Mid-Bay and Lateral Station Water Quality Data in the Chesapeake Bay Mainstem

Published:

June 1, 1993

Associated with:

Water Quality Goal Implementation Team (GIT 3)

Seasonal median water quality values were compared between stations in mid-Bay and lateral regions in seven east-west transects in the mainstem Chesapeake Bay. Comparisons were made over seven years, 1985-1991, for April-October surface layer medians of total phosphorus, total nitrogen, dissoslved orthophosphate, dissolved inorganic nitrogen, total suspended solida, chlorophyll a, Secchi depth, and salinity. Comparisons were also made using spring (March-May) and summer (June-September) medians of surface and bottom salinity and dissolved oxygen. Comparisons were made using difference plots of raw data, scatter plots of annual seasonal medians, nand the Wilcoxon matched-pairs test on annual seasonal medians. The graphical and statistical analyses confirmed each other. Correlation coefficients were also calculated between mid-Bay and lateral data series to estimate their degree of similarity over time, but could not be tested for statistical significance.