posted on 2021-04-22, 15:33authored byAlisha Prasad, Sushant P. Sahu, Sara Karoline Figueiredo Stofela, Ardalan Chaichi, Syed Mohammad Abid Hasan, Wokil Bam, Kanchan Maiti, Kevin M. McPeak, Gang Logan Liu, Manas Ranjan Gartia
Phosphate is a major
nonpoint source pollutant in both the Louisiana
local streams as well as in the Gulf of Mexico coastal waters. Phosphates
from agricultural run-off have contributed to the eutrophication of
global surface waters. Phosphate environmental dissemination and eutrophication
problems are not yet well understood. Thus, this study aimed to monitor
phosphate in the local watershed to help identify potential hot spots
in the local community (Mississippi River, Louisiana) that may contribute
to nutrient loading downstream (in the Gulf of Mexico). An electrochemical
method using a physical vapor deposited cobalt microelectrode was
utilized for phosphate detection using cyclic voltammetry and amperometry.
The testing results were utilized to evaluate the phosphate distribution
in river water and characterize the performance of the microsensor.
Various characterizations, including the limit of detection, sensitivity,
and reliability, were conducted by measuring the effect of interferences,
including dissolved oxygen, pH, and common ions. The electrochemical
sensor performance was validated by comparing the results with the
standard colorimetry phosphate detection method. X-ray photoelectron
spectroscopy (XPS) measurements were performed to understand the phosphate
sensing mechanism on the cobalt electrode. This proof-of-concept sensor
chip could be utilized for on-field monitoring using a portable, hand-held
potentiostat.