Sources, pathways and sinks of litter within riverine and marine environments.
This research was developed as one of the first studies to investigate riverine litter
problems. Baseline assessment methods were formulated to define the scope and
nature of this pollution form. Assessments were carried out in three catchments; the
Taff East Lyn and Avill. The Taffwas found to be atypical regarding the extent of the
litter. In all catchments plastic sheeting formed the principal litter component.
The study also included an examination of the factors influencing the sources,
pathways and sinks riverine litter pollution. These factors were drawn together
through the development of a research model. Assessments of two quantifiable
sources, sewage inputs through Storm Water Overflows (SWOs) and fly-tipping
wastes, were undertaken. Greatest inputs of sewage-derived solids were introduced to
the river through malfunctioning SWOs, the most numerous single component being
sanitary towels. Whilst sewage-derived material constituted approximately 23% of all
items on the River Taff large quantities of waste, especially plastic sheeting, originated
from fly-tipping sites.
Mobility of litter once introduced to the system was greatly dependent on river flow
regimes. Some litter types, e.g. plastic sheeting, were more mobile than others and
tended, after floods, to be stranded on vegetation.
Due to its high profile within the catchments and expected longevity, plastic sheeting
was chosen for river-bank degradation trials. Results indicated that photodegradation
occurred within samples, but only in the initial exposure period and that any further
breakdown was likely to result from physical abrasion.
Marine areas were considered to be potential sinks for riverine litter, especially its
more mobile components. An alternative sink for certain litter types such as cloth
might be incorporation into the river-bank due to an ability to aggregate soil/sediment