Plastic litter assessment of the riverbanks of Pulot River and its tributary in Sofronio Española, Palawan Island, Philippines

Rivers are essential sources of plastic litter in the marine environment. Recently, the Philippines was reported as the biggest polluter of plastic litter from riverine sources. However, the riverine plastic litter's origin has been less established. In this study, we determined the density, composition, and accumulation of plastic litter on the riversides of Pulot River and its tributary in Palawan Island, Philippines. We also identified the possible sources of plastic litter. Results showed that the plastic litter density was highest at the river edge during the first sampling period. Litter densities for the predefined zones and sampling periods all showed no significant differences. The most dominant plastic litter types were food packaging and plastic bags, followed by toiletries. ‘Others’ consisted of multilayers, mixed, and plastics accounted for the most abundant polymer types. We identified the residents in the vicinity illegally dumping litter, for there were small illegal dumping sites along the river. These results suggest the urgent need for better waste policy implementation measures to protect the riparian environments and reduce the input of riverine plastic litter into the marine environment to ensure river resource sustainability.