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When an organism occupies a high trophic level, like orcas or humans, they will accumulate more PCBs than an organism that occupies a low trophic level, like phytoplankton. If enough organisms with a trophic level are killed due to the accumulation of toxins, like PCB, a trophic cascade can occur.
Bioremediation of PCBs is the use of microorganisms to degrade PCBs from contaminated sites, relying on multiple microorganisms' co-metabolism. Anaerobic microorganisms dechlorinate PCBs first, and other microorganisms that are capable of doing BH pathway can break down the dechlorinated PCBs to usable intermediates like acyl-CoA or carbon ...
Microbial biodegradation is the use of bioremediation and biotransformation methods to harness the naturally occurring ability of microbial xenobiotic metabolism to degrade, transform or accumulate environmental pollutants, including hydrocarbons (e.g. oil), polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), heterocyclic compounds (such as pyridine or quinoline ...
The inclusion of PCBs as a PBT may be attributed to their low water solubility, high stability, and semi-volatility facilitating their long range transport and accumulation in organisms. [5] The persistence of these compounds is due to the high resistance to oxidation, reduction, addition, elimination and electrophilic substitution. [ 6 ]
Test results conducted in the fall showed the presence of PCBs, or polychlorinated biphenyls — toxic, man-made chemicals that were banned from being produced in the United States in 1979 ...
At every stage or trophic level, the concentration is higher, because the persistent chemicals are not "burned off" when the higher organism uses the fat of the prey organism to produce energy. Due to bioaccumulation and biomagnification, the species at the top of the trophic pyramid are most vulnerable to dioxin-like compounds.
Before they can be registered for sale in most countries, xenobiotic pesticides must undergo extensive evaluation for risk factors, such as toxicity to humans, ecotoxicity, or persistence in the environment. For example, during the registration process, the herbicide, cloransulam-methyl was found to degrade relatively quickly in soil. [10]
The degradation rate of many organic compounds is limited by their bioavailability, which is the rate at which a substance is absorbed into a system or made available at the site of physiological activity, [11] as compounds must be released into solution before organisms can degrade them. The rate of biodegradation can be measured in a number ...