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Goal: Apply Knowledge Globally Assessment of surface water quality in the Big Sunflower River watershed of the Mississippi Delta

Big Sunflower River in Mississippi Delta
Big Sunflower River in Mississippi Delta. (Forest Service photo by Ying Ouyang)

Introduction

The Big Sunflower River Watershed in the Mississippi Delta is an area of intensive crop production. Nutrients, suspended solids, low dissolved oxygen, and pathogens are among its water quality concerns. With better understanding of the importance of drinking water quality to public health, raw water quality to ecosystems, and eutrophication of the Gulf of Mexico, there is a greater need to assess surface water quality in this area. SRS scientists conducted field measurement and nonparametric analysis to assess the characteristics, seasonal variations, annual trends, and correlations of some surface water quality constituents in the Big Sunflower River Watershed.

Summary

Assessment of surface water quality in the Mississippi Delta is essential to quantify the eutrophication of the Gulf of Mexico. SRS scientists and colleagues took field measurements and applied nonparametric analysis to assess the characteristics and variations of surface water quality at three study sites in the Big Sunflower River Watershed of the Mississippi Delta.

Results showed that nitrate-nitrogen (NO3-N) and total phosphorus varied from site to site each year. However, variations of pH and dissolved oxygen were basically insignificant. The highest median concentrations were found in spring for NO3-N and total nitrogen; in summer for specific conductance, Na, and Cl; and in winter for dissolved oxygen. Mann-Kendall trend analysis revealed that there was an increasing annual trend at Leland but a decreasing annual trend at Merigold for NO3-N concentrations even though such changes were very small, whereas there was no annual trend for total phosphorus at any of the three study sites. Pettitt’s test further identified that the NO3-N concentrations had an abrupt increase in February 2009 in Leland and an abrupt decrease in June 2012 in Merigold. A very good linear correlation existed between total dissolved solids and magnesium.

Principal Investigator
Ying Ouyang, Research Hydrologist
RWU
4155 - Center for Bottomland Hardwoods Research
Strategic Program Area
Resource Management and Use
Water, Air, and Soil
Publication
Assessment of surface water quality in the Big Sunflower River Watershed of Mississippi Delta using nonparametric analysis
Research Partner
Theodor Leininger (SRS)
External Partners
Gary Feng (USDA ARS)
Johnie N. Jenkins (USDA ARS)
Prem Parajuli (Mississippi State University)
Yongshan Wan (US EPA Gulf Ecology Division)