Study links plastic litter, seawater temperature, ocean acidification

Litter is found in all the world’s oceans and seas, even in remote areas far from human contact and obvious sources of the problem. According to the International Maritime Organisation, marine litter creates a huge problem in the oceans, with some scientists warning that, by 2050, the quantity of plastics in the oceans will outweigh fish.

Plastic materials in all shapes and sizes can break down extremely slowly in the marine environment. Research by Reddy et al estimated in 2018 that it takes over 400 years.

Marine litter originates from many sources and causes a wide range of environmental, economic, safety, health and cultural impacts. For example, marine litter can harm or kill sea creatures if they eat it or if a marine mammal becomes entangled in litter.

But there are other consequences as a result of all this litter ending up in the oceans and seas. Does plastic affect seawater conditions?

Following an outdoor classroom activity at Ħondoq Bay, a small sandy beach in the southeast of Gozo, students from Gozo College Middle School decided to study the effects of plastic litter on seawater temperature and seawater acidity (pH) levels.

Taking some seawater to school, two large glass jars were filled with the same amount of seawater. Some plastic litter collected during the clean-up activity was put in one of the jars. The glass jars were placed outside, exposed to the sun and rain.

Every day three readings of the seawater temperature and pH level from both jars were taken. The mean of the three samples was calculated. Moreover, the air temperature, humidity and air pressure were also measured and cloud cover observed using the Globe Observer App, also describing the general weather conditions.

All data gathered was analysed by comparing mean values of pH and temperature between the two jars with and without plastic litter. The mean values were plotted along time to verify the changes between the two. Finally, the mean values were further analysed, with the help of a scientist, using a paired sample-T test, to verify meaningful differences between the two conditions and pH and temperature. Once all data was collected the data was presented in a graph . . . .

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