Drones for litter mapping: An inter-operator concordance test in marking beached items on aerial images.

Unmanned aerial systems (UAS, aka drones) are being used to map macro-litter on the environment. Sixteen qualified researchers (operators), with different expertise and nationalities, were invited to identify, mark and categorize the litter items (manual image screening, MS) on three UAS images collected at two beaches. The coefficient of concordance (W) among operators varied between 0.5 and 0.7, depending on the litter parameter (type, material and colour) considered. Highest agreement was obtained for the type of items marked on the highest resolution image, among experts in litter surveys (W = 0.86), and within territorial subgroups (W = 0.85). Therefore, for a detailed categorization of litter on the environment, the MS should be performed by experienced and local operators, familiar with the most common type of litter present in the target area. This work provides insights for future operational improvements and optimizations of UAS-based images analysis to survey environmental pollution.

The impact of anthropogenic litter on Colombia's central Caribbean beaches.

A total of 7563 anthropogenic litter (AL) items, grouped into twelve different typologies, were collected along 25 beaches located on the central Caribbean coast of Colombia. The average AL abundance was 6.05 items/m2, plastic items being the most common reaching a total percentage of 88.9% with an average density of 5.38 items/m2. Application of 3 evaluation indices, based on the AL data, placed most of the beaches into the status of unacceptable conditions of cleanness (Dirty to Extremely Dirty), and into mediocre to unsatisfactory environmental status. Hazardous anthropogenic litter (HAL), occurred in considerable amounts with hazardous items reaching a high of 7% (502 items of 7563 total items collected), and an average of 0.40 items/m2. Beaches were statistically grouped into four specific types that ranged from beaches in good environmental conditions (Group A) to beaches in extremely adverse environmental conditions (Group D). The typology and magnitudes of AL found along the study area suggest a combination of sources that are associated with the multiple usages developed along this region's coast. Anthropogenic litter is mainly related to land-based sources, and these generating source activities can be found in nearby basins and/or on the same beaches where the litter remains. This paper proposes four key actions to specifically reduce AL, as well as an 8-step agenda to address solutions to the broader management of litter problems.

Abundance and distribution of beach litter along the Atlantico Department, Caribbean coast of Colombia.

A total of 5993 litter items divided into 13 categories were found at 25 beaches located along the Atlantico Department coastline, Caribbean of Colombia, with an average litter abundance of 7 items/m. Agglomerative Hierarchical Clustering (AHC), Multidimensional Scaling (MDS) and Principal Components Analysis (PCA) were applied with the objective of highlighting similarities and contrasts between litter categories and abundances. Results indicated two specific groups of beaches in terms of amounts of litter. The first group is composed of 17 "dirty beaches" (urban, resort and village) while the second group includes 8 "clean beaches" (village and resort). This division was confirmed by means of the EA/NALG (2000) grading system, which highlighted that 68% of beaches belonging to the Atlantico Department coastline are in an unacceptable condition of cleanness. Current patterns of litter abundance and accumulation are related to sources as well as beach characteristics such as degree of exposition and morphodynamic state.