Using a Low-Cost Green Light Emitting Diode to Measure Total Suspended Solids in a Marine Protected Area of the Philippines

Abstract

Fernandez, P.N.J., 2022. Using a low-cost green light emitting diode to measure total suspended solids in a marine protected area of the Philippines. Journal of Coastal Research, 38(1), 99–113. Coconut Creek (Florida), ISSN 0749-0208. Seawater parameters are important indicators of coastal water conditions. One of the essential parameters is the total suspended solids (TSS). This study probed how to use a low-cost 535-nm green LED to measure the TSS in marine protected areas of barangay Lo-ong, Concepcion, Iloilo, Philippines. It aims to examine the relationship of the total attenuation coefficients (TAC) to total suspended solids (TSS) values in coastal water. Sample sea waters were taken from various locations and brought to a laboratory for a filtration process known as gravimetry. Different available filter paper sizes (1.5 microns, 6 microns, 20 microns, and 50 microns) were used in the filtration process and were dried in a controlled constant temperature of 110 degrees Celsius for 24 hours using an electric oven. Dried filter papers' weights were measured using an analytical balance before using the infiltration of seawater. TAC values were also measured in different seawater samples using a prototype device made up of LED and photodiode. This study demonstrated that TAC values of green LEDs are positively correlated with TSS values (R value of 0.45). Results reveal that the moderate correlation between an LED's TAC values to TSS positively proved that a low-cost LED can be used as an alternative to the more expensive remote sensing satellite data. Findings of the study also showed that TSS values in the marine protected area under study were far below the acceptable limits for coastal waters. The performance of the LED-based measuring device can still be improved in the future by using collimating lenses and more sensitive photomultiplier tubes.