Bioaccumulation
Bioaccumulation is the gradual accumulation of substances, such as
Toxicity induced by metals is associated with bioaccumulation and biomagnification.[7] Storage or uptake of a metal faster than it is metabolized and excreted leads to the accumulation of that metal.[8] The presence of various chemicals and harmful substances in the environment can be analyzed and assessed with a proper knowledge on bioaccumulation helping with chemical control and usage.[9]
An organism can take up chemicals by breathing, absorbing through skin or swallowing.[7] When the concentration of a chemical is higher within the organism compared to its surroundings (air or water), it is referred to as bioconcentration.[1] Biomagnification is another process related to bioaccumulation as the concentration of the chemical or metal increases as it moves up from one trophic level to another.[1] Naturally, the process of bioaccumulation is necessary for an organism to grow and develop; however, the accumulation of harmful substances can also occur.[7]
Examples
Terrestrial examples
An example of poisoning in the workplace can be seen from the phrase "
Some animal species use bioaccumulation as a mode of defense: by consuming toxic plants or animal prey, an animal may accumulate the toxin, which then presents a deterrent to a potential predator. One example is the tobacco hornworm, which concentrates nicotine to a toxic level in its body as it consumes tobacco plants. Poisoning of small consumers can be passed along the food chain to affect the consumers later in the chain.
Other compounds that are not normally considered toxic can be accumulated to toxic levels in organisms. The classic example is vitamin A, which becomes concentrated in livers of carnivores, e.g. polar bears: as a pure carnivore that feeds on other carnivores (seals), they accumulate extremely large amounts of vitamin A in their livers. It was known by the native peoples of the Arctic that the livers of carnivores should not be eaten, but Arctic explorers have suffered hypervitaminosis A from eating the livers of bears; and there has been at least one example of similar poisoning of Antarctic explorers eating husky dog livers. One notable example of this is the expedition of Sir Douglas Mawson, whose exploration companion died from eating the liver of one of their dogs.
Aquatic examples
Fish are typically assessed for bioaccumulation when they have been exposed to chemicals that are in their aqueous phases.
Naturally produced toxins can also bioaccumulate. The marine
Wetland acidification can raise the chemical or metal concentrations, which leads to an increased bioavailability in marine plants and freshwater biota.[16] Plants situated there which includes both rooted and submerged plants can be influenced by the bioavailability of metals.[16]
Studies of turtles as model species
Bioaccumulation in
The most common elements studied in turtles are mercury, cadmium, argon[dubious ], and selenium. Heavy metals are released into rivers, streams, lakes, oceans, and other aquatic environments, and the plants that live in these environments will absorb the metals. Since the levels of trace elements are high in aquatic ecosystems, turtles will naturally consume various trace elements throughout various aquatic environments by eating plants and sediments.[18] Once these substances enter the bloodstream and muscle tissue, they will increase in concentration and will become toxic to the turtles, perhaps causing metabolic, endocrine system, and reproductive failure.[19]
Some marine turtles are used as experimental subjects to analyze bioaccumulation because of their shoreline habitats, which facilitate the collection of blood samples and other data.[18] The turtle species are very diverse and contribute greatly to biodiversity, so many researchers find it valuable to collect data from various species. Freshwater turtles are another model species for investigating bioaccumulation.[20] Due to their relatively limited home-range freshwater turtles can be associated with a particular catchment and its chemical contaminant profile.
Developmental effects of turtles
Toxic concentrations in turtle eggs may damage the developmental process of the turtle. For example, in the Australian freshwater short-neck turtle (Emydura macquarii macquarii), environmental PFAS concentrations were bioaccumulated by the mother and then offloaded into their eggs that impacted developmental metabolic processes and fat stores.[21] Furthermore, there is evidence PFAS impacted the gut microbiome in exposed turtles.[22]
In terms of toxic levels of heavy metals, it was observed to decrease egg-hatching rates in the Amazon River turtle, Podocnemis expansa.[19] In this particular turtle egg, the heavy metals reduce the fat in the eggs and change how water is filtered throughout the embryo; this can affect the survival rate of the turtle egg.[19]
See also
- Biomagnification (magnification of toxins with increasing trophic level)
- Chelation therapy
- Drug accumulation ratio
- Environmental impact of pesticides
- International POPs Elimination Network
- Persistent organic pollutants
- Phytoremediation (removal of pollutants by bioaccumulation in plants)
References
- ^ ISBN 978-0-412-74050-3.
- JSTOR 2418066.
- PMID 22324398.
- .
- PMID 19919169.
- PMID 22321051.
- ^ ISBN 978-0-08-043751-4, retrieved 17 February 2021
- S2CID 12568097.
- )
- PMID 13658944.
- ^ "Mercury: What it does to humans and what humans need to do about it". IISD Experimental Lakes Area. 23 September 2017. Retrieved 6 July 2020.
- ^ )
- PMID 32326183.
- PMID 17472629.
- PMID 37701825.
- ^ .
- .
- ^ S2CID 247638704.
- ^ S2CID 232315423.
- PMID 34715216.
- PMID 35026273.
- S2CID 249213966.