Marine Debris Project Final Report 2014

8.2 Container Deposit: an effective policy for reducing litterCSIRO analysed a dataset on litter clean-ups provided by CleanUp Australia (CUA; www.cleanup.org.au) toevaluate whether there are any differences in the types of litter that are found among the states.Specifically, we asked whether sites in South Australia, which has a container deposit scheme, had fewerbeverage containers in the waste stream. CleanUp Australia provided counts of the number of items ineach of 94 categories across 750 sites in their 2012 clean-up (Table 1). Due to missing information fromsome records, we reduced the dataset down to 693 records. These records cover clean-ups from a widerange of sites, including parks, schools, beaches, waterways, etc. The CUA data does not includeinformation on the total area covered by a clean-up, nor does it include detailed information on the effort,aside from the number of people involved. Given these limitations, we chose to look at the relativefrequencies of beverage containers in the clean-ups as a metric of the effect of the container depositscheme. Beverage containers were restricted to seven of the 94 categories and included PET drinkcontainers, non-PET containers, alcoholic beverage bottles, soft drink bottles, fruit juice bottles, alcoholicbeverage and soft drink containers. Drink cartons, milk cartons, bottle caps and straws were not included asbeverage containers in this analysis.Table 2. The number of sites cleaned up in each state or territory as part of the 2012 Clean Up AustraliaDay activities. For a full listing of the 94 categories of items, please refer to the CleanUp Australia website(www.cleanup.org.au).Australian Capital Territory 7New South Wales 235Northern Territory 9Queensland 168South Australia 63Tasmania 29Victoria 127Western Australia 55We used regression analysis to compare the frequency of beverage containers with the frequency of otheritems in the clean-up data. We found that a model that included the state as an explanatory factor wassignificantly better than a model that assumed that the ratio of beverage containers to other items wasconstant nationwide based on Aikaike Information Criterion (AIC; constant everywhere: 61440, differ bystate: 54624). We examined the differences between the various states using a multiple comparison test toevaluate whether pairs of regression coefficients for each state were different.56 | Understanding the effects of marine debris on wildlife