Three year summary Lake Geneva

Notebook 3

Purpose: Present an analysis method for survey results from beach litter inventories on Lake Geneva.

Background: This is in the context of the global movement to reduce plastic debris in the maritime environment. Riverine inputs are major contributors of plastic debris (and all types of refuse) to the oceans. This is an analysis of the data collected on the shores of Lake Geneva over a three year period. The maritime protocol was modified in very specific ways to adjust for the local geography and population density.

Research question: Is this a representative sample ?

From notebooks one and two we can assume the following:

  1. The data was collected at different locations
  2. The data was collected by different groups of people
  3. For each year there is one group that collected 50% or more of the samples
  4. The mean for each year is 9pcs/m +/- 1
  5. The median for each year is 5.5pcs/m +/- 1.3
  6. The numnber of samples for each year is different
  7. Each year has a geographic center
  8. All the particpants recieved training on a standardized protocol

The survey totals, in pieces of trash per meter, can be summarised as follows:

Statistic Year one Year two Year three Combined
Samples 83 41 24 148
mean 8.77 9.99 9.01 9.16
median 4.83 6.84 4.24 5.52
Std dev 9.92 8.52 16.14 10.75
25\%ile 3.113 4.41 2.36 3.18
75\%ile 10.405 12.35 7.79 11.24
Minimum 0.68 0.57 0.11 0.11
Maximum 50.075 39.54 77.05 77.05
MCBP samples 80 22 5 107
SLR samples 0 18 15 33
EPFL samples 2 2 2 6
PC samples 0 0 2 2

Object category frequency and density year over year:

  1. What are the most common categories identified?
  2. What are the differences between groups and year over year results?
  3. How do the individual results relate to the cumulative results?
Directory already in place

Cumulative results all surveys Nov 2015 - Nov 2018

Year one

Year two

Year three