Plastic shotgun shell wadding

4. Plastic shotgun shell wadding#

A summary of observations on Lac Léman

Plastic wadding is commonly used in modern shotgun shells due to its durability and consistency in performance. It helps to cushion the shot or slug as it moves down the barrel, ensuring it stays centered and providing a proper seal to maximize the energy transfer upon firing.

Plastic wadding can come in various forms, such as wads or cups, and they can have different designs depending on the specific requirements of the shotgun shell and the desired performance characteristics.

When plastic wadding is left behind after shooting activities or improperly disposed of, it can find its way into water bodies and eventually wash up on beaches. Once there, it can pose risks to wildlife through ingestion or entanglement.

4.1. Essential statistics: 2015 - 2021#

Effective dates from 2015-11-23 00:00:00 to 2021-11-14 00:00:00

Total found: 949

Number of samples: 250

Number of municipalities: 15

Number of unique sample locations: 38

Shotgun wadding found in 54% of samples

The average number found per sample 3, the median found 1.0

The average number found per meter of shoreline 0.1, the median found per meter of shoreline 0.02

Historical average for every 100 meters : 10, historical median 2

The historical 95% range per 100 meter {0.05: 0, 0.25: 0, 0.5: 2, 0.75: 8, 0.95: 54}

4.1.1. Characteristics and weight of sampling conditions#

We assume there is a relationship between how the land is used and what it is we find on the ground. Archeaologists and Anthropologists make this basic assumption every time they undertake an excavation and interpret the results in the context of other findings. This interpretation of beach litter data does exactly the same. As discussed in Near or far and the federal report IQAASL : at the national level there is strong evidence to support a correlation between the density of objects found and specific topographic features that can be isolated on a standard topographical map.

Here we consider the following features as a % of the dry-land surface area within 1 500 meters of the survey location:

Buildings: the surface area attributed to constructed spaces
Forest: the surface are attributed to woods and forest
Orchards: the surface area attributed to orchards
Public services: the surface area attributed to any area that is associated to public use, includes hospitals, sports fields, schools etc.
Undefined: the surface area has no defined use
Vineyards: the surface area attributed to growing grapes for wine making

4.1.2. Categories#

The magnitued of the land-use features are divided into categories: 1 - 5. Each category represents the relative magnitude of the land use conditions, as a % of the available dryland from a surface area that is equal to a circle with of radius 1’500 metres centered at the survey location: a buffer zone. The term dry-land refers to the available surface area of the buffer zone that is not covered with water.

Consider the tables 1 and 2. The % of samples that were conducted in locations with the least amount of surface area dedicated to orchards is 91% (table 1), the average pieces per meter for locations with that attribute was 0.11 (table 2).

For a detailed description of how these values are derived: Extracting land-use values

**Table 1:** Percent of samples collected with the designated land-use feature and category.
	orchards	vineyards	buildings	forest	undefined	public_services
1	91%	92%	11%	72%	63%	68%
2	6%	7%	6%	14%	25%	7%
3	0%	0%	1%	0%	1%	7%
4	1%	0%	20%	9%	2%	8%
5	1%	1%	62%	5%	9%	10%

**Table 2:** The average number of shotgun shells per linear meter of shoreline by feature and category.
	buildings	forest	orchards	public_services	undefined	vineyards
1	0.03	0.08	0.11	0.13	0.09	0.10
2	0.59	0.06	0.01	0.12	0.18	0.08
3	0.00	-	0.00	0.01	0.08	-
4	0.04	0.00	0.01	0.03	0.09	0.00
5	0.09	0.68	0.14	0.03	0.00	0.12

4.1.3. Regional results#

Lake Geneva is divided into three parts because of its different types of formation (sedimentation, tectonic folding, glacial erosion):

Haut Lac (‘Upper Lake’), the eastern part from the Rhône estuary to the line of Meillerie–Rivaz
Grand Lac (‘Large Lake’), the largest and deepest basin with the lake’s largest width
Petit Lac (‘Small Lake’), the most south-west, narrower and less deep part from Yvoire–Promenthoux next Prangins to the exit in Geneva

For a brief description of the geography of Lac Léman see: Wikepedia Lake Geneva

_images/fd4a5a20a1d5de0d07a1d632888515bd25d1d82bc3af9171215c6a24d44174c3.png

Figure 1: Survey totals in number of shotgun shell waddings per linear meter of shoreline, November 2015 - December 2021.

_images/fdd22bceafafcb7a9c5149fef4f740fe7cf5647be813cc255e6028f51f67ba09.png

Figure 2: The empirical cumulative distribution (ECDF) of the survey results.

Table 3: The qauntile range of the number of plastic shotgun shells found per meter of shoreline by region. ^^

The distribution of the number of shotgun wadding found per meter of shoreline
	nsamples	mean	std	50%	75%	max
Grand lac	58.00	0.03	0.05	0.00	0.03	0.22
Haut lac	137.00	0.17	0.31	0.05	0.17	1.64
Petit lac	55.00	0.02	0.05	0.00	0.01	0.30

4.1.4. Municipal results#

There are numerous municipalities on the lake, here we consider only the municipalities that were sampled.

Nummber of cities with two or more samples where none were found: 0

Cities where none were found, for all cities and number of samples: ['Morges' 'Rolle']

Municipal results in descending order

	pcs/m	nsamples
Saint-Gingolph	0.68	13
Allaman	0.14	3
Bourg-en-Lavaux	0.12	2
La Tour-de-Peilz	0.12	25
Montreux	0.11	53
Vevey	0.11	44
Saint-Sulpice (VD)	0.06	15
Versoix	0.05	4
Genève	0.03	29
Préverenges	0.01	15
Tolochenaz	0.01	3
Lausanne	0.01	20
Gland	0.00	22
Morges	0.00	1
Rolle	0.00	1

4.2. Essential statistics: 2022#

Effective dates from 2022-01-10 to 2022-12-17

Total found: 199

Number of samples: 98

Number of municipalities: 24

Number of unique sample locations: 25

Shotgun wadding found in 38% of samples

The average number found per sample 2, the median found 0.0

The average number found per meter of shoreline 0.02, the median found per meter of shoreline 0.0

Historical average for every 100 meters : 2, historical median 0

The historical 95% range per 100 meter {0.05: 0, 0.25: 0, 0.5: 0, 0.75: 2, 0.95: 9}

4.2.1. Regional results 2022#

The distribution of the number of shotgun wadding found per meter of shoreline
	nsamples	mean	std	75%	max
Grand lac	47.00	0.03	0.06	0.03	0.36
Haut lac	24.00	0.03	0.06	0.03	0.29
Petit lac	27.00	0.01	0.02	0.00	0.07

4.2.2. Municipal results 2022#

Nummber of cities with two or more samples where none were found: 10

Cities where none were found, for all cities and number of samples: ['Anthy' 'Aubonne' 'Crans' 'Cully' 'Gland' 'Hermance' 'Meillerie' 'Rolle'
 'Tolochenaz' 'Tougues']