Author(s)

KAIRE TORN, GEORG MARTIN, GRETA REISALU

Abstract

Littering and microplastic are a rising problem in both the terrestrial and marine environment. The degradation of macrolitter into smaller particles is driven by several factors such as: material, temperature, UV light, grazers, etc. Field exposure experiments were conducted within the natural systems to assess how quickly fragmentation occurs under different environmental conditions. The degradation of disposable paper plates, biodegradable plates, and biodegradable waste bags was studied in two terrestrial (open-air vs. buried in soil) and two marine (submerged in seawater above sediment vs. buried in sediment) conditions. Additionally, both biodegradable items were labelled as compostable by the producer. Degradation under natural condition did not meet established official standards for the biodegradation. Products degradation rates were highest in the marine environment for sample products that were submerged in seawater but above the sediment, followed by those that were in the terrestrial environment and buried in the soil. The rate of degradation was affected by the prevalence of grazers in combination with wave action for the litter submerged in seawater but above the sediment. The biodegradable plates were completely degraded under these two conditions within 4 months. The loss of material was highest during the first months. Slowest degradation occurred in the open-air where the loss of all materials was only 8–17% after 10 months. Biodegradable plastic bags decomposed remarkably only in the seawater above the sediment, in other environments the loss of weight was less than 20% during the period of 10 months.

Keywords

discarded macrolitter, plastic pollution, biodegradable products, plastic deterioration, fragmentation, sea water, natural environment