To quantify microplastic contamination in benthic marine environments, researchers employ a multi-step density separation and chemical digestion protocol. First, wet sediment core samples are dried in an oven at to obtain a constant dry weight. The dried sediment is then mixed with a high-density saturated sodium chloride () solution and stirred vigorously to liberate lighter plastic polymers from the heavier mineral matrix. After allowing the mixture to settle, the supernatant containing suspended microplastics is decanted through a sieve. Subsequently, the material retained on the sieve is rinsed and transferred to a beaker for chemical digestion. To eliminate organic matter that could interfere with spectroscopy, a hydrogen peroxide () solution is added, and the mixture is heated. Crucially, the temperature must not exceed to prevent the thermal degradation of low-density polymers. Once the organic material is digested, the remaining solution is vacuum-filtered through a glass fiber filter and analyzed using spectroscopy.
Based on the passage, if a researcher omits the density separation step using the saturated sodium chloride () solution but carries out all other steps as described, which of the following is the most likely consequence?
- The final spectroscopic analysis will be compromised because the heavier mineral matrix will remain mixed with the microplastics on the filter.Cevap
- BThe organic matter in the sediment will not be digested because hydrogen peroxide requires the presence of salt to act as a chemical catalyst.
- CThe low-density plastic polymers will thermally degrade during the heating phase due to the absence of the sodium chloride solution's buffering effect.
- DThe supernatant cannot be decanted through the sieve because the microplastics will remain bound to the wet sediment.