Final answer:
Biotic degradation by bacteria and fungi, along with UVB radiation and sunlight-related abiotic processes, contribute significantly to the degradation of organic matter in ecosystems as part of natural biogeochemical cycles.
Step-by-step explanation:
To address the question of how much of the observed degradation (the 40%) can be ascribed to various factors, we need to consider different processes such as biotic degradation (bacteria and fungi), UVB radiation, other wavelengths of radiation, and other abiotic processes. Biotic degradation through bacteria and fungi is a crucial aspect of the biogeochemical cycles, as these organisms help break down organic matter and recycle nutrients like carbon, nitrogen, and phosphorus within ecosystems.
UVB radiation can cause damage to living organisms and affect the breakdown of materials, especially at the Earth's surface layers. When considering full sunlight and the abiotic processes it entails, including UV radiation but also heat and visible light, it is well-known that these can accelerate the degradation of organic matter.
Therefore, although the specific percentages are not provided in the reference information, we can infer that abiotic processes other than sunlight would likely contribute a smaller portion to the degradation of organic material compared to biotic degradation and sunlight-related processes. The direct effects of radiation on degradation, particularly UVB radiation, and biotic factors like bacteria and fungi are significant and could account for a majority of the percentage indicated.