Study on metal ion release from shotgun ammunition in water bodies
Because of the risk of poisoning for birds and the environment, hunting with shotgun ammunition (lead shot) is now severely restricted or banned altogether in many countries. But alternative ammunition does not have to be harmless, as a team from the Technical University of Munich (TUM) has shown in a recent study.
Due to its ballistic properties, shot ammunition (lead shot) was previously considered the optimal ammunition for hunting waterfowl. This material came under criticism when lead poisoning was observed in ducks and white-tailed eagles that had ingested the shot pellets while burrowing or with their prey.
In the meantime, ammunition manufacturers offer a range of alternative hunting shot containing iron, copper, zinc, tungsten or bismuth as declared main components. However, a team from the Technical University of Munich led by Prof. Dr. Axel Göttlein and Prof. Dr. Jürgen Geist has come to the conclusion that some of the alternatives are even more toxic to aquatic organisms than conventional lead ammunition.
Ammunition with risks and side effects - überraschende Ergebnisse bei der Messung der Metallwerte
Within the scope of the study, shot balls of the different material types were exposed to water under the same conditions in each case. On the one hand, it was found that the metal ion release into the solution was very different: While shot made of tungsten, bismuth and a coated lead shot released almost no metal ions into the water solution, alarmingly high concentrations were measured for shot made of copper and zinc.
Secondly, the researchers found that it was not necessarily the main component of the shot material that dominated the ion release. Particularly striking here was an iron shot that released large amounts of zinc, which obviously came from a coating.
Rethink prohibitions
In a DIN standardized immobilization test with the large water flea, the mobility of the animals is considered an indicator of their vitality. As the study showed, even small amounts of copper and zinc always led to very high to total immobilization of the water fleas, while meals of pure iron, bismuth and tungsten did not affect the mobility of the water fleas. Lead shot also did not significantly affect the mobility of water fleas compared to a control group.
If a ban on lead shot is demanded for environmental protection reasons, the metals copper and zinc for shot production would also have to be banned without fail according to the current state of knowledge, the study concludes. However, since very different conditions of water quality with the correspondingly adapted organisms occur in nature, further studies are absolutely necessary in order to place decisions on alternatives to lead shot on a secure basis.
Publication:
Fäth J, Feiner M, Beggel S, Geist J, Göttlein A: Leaching behavior and ecotoxicological effects of different game shot materials in freshwater. Knowledge & Management of Aquatic Ecosystems. (419); 24, 2018. DOI: 10.1051/kmae/2018009
https://www.kmae-journal.org/articles/kmae/abs/2018/01/kmae170148/kmae170148.html
