Plant leaf litter has a major role in the structure and function of soil ecosystems as it is associated with nutrient release and cycling. The present study is aimed to understand how well the decomposing leaf litter kept soil organic carbon and nitrogen levels stable during an incubation experiment that was carried out in a lab setting under controlled conditions and the results were compared to those from a natural plantation. In natural site soil samples, Anacardium. occidentale showed a higher value of organic carbon at surface (1.14%) and subsurface (0.93%) and Azadirachta. indica exhibited a higher value of total nitrogen at surface (0.28%) and subsurface sample (0.14%). In the incubation experiment, Acacia auriculiformis had the highest organic carbon content initially (5.26%), whereas A. occidentale had the highest nitrogen level on 30th day (0.67%). The overall carbon-nitrogen ratio showed a varied tendency, which may be due to dynamic changes in the complex decomposition cycle. The higher rate of mass loss and decay was observed in A. indica leaf litter, the range of the decay constant is 1.26-2.22. The morphological and chemical changes of soil sample and the vermicast were substantained using scanning electron microscopy (SEM) and Fourier transmission infrared spectroscopy (FT-IR).
Polycyclic aromatic hydrocarbons (PAHs) are considered a major class of organic contaminants or pollutants, which are poisonous, mutagenic, genotoxic, and/or carcinogenic. Due to their ubiquitous occurrence and recalcitrance, PAHs-related pollution possesses significant public health and environmental concerns. Increasing the understanding of PAHs' negative impacts on ecosystems and human health has encouraged more researchers to focus on eliminating these pollutants from the environment. Nutrients available in the aqueous phase, the amount and type of microbes in the culture, and the PAHs' nature and molecular characteristics are the common factors influencing the microbial breakdown of PAHs. In recent decades, microbial community analyses, biochemical pathways, enzyme systems, gene organization, and genetic regulation related to PAH degradation have been intensively researched. Although xenobiotic-degrading microbes have a lot of potential for restoring the damaged ecosystems in a cost-effective and efficient manner, their role and strength to eliminate the refractory PAH compounds using innovative technologies are still to be explored. Recent analytical biochemistry and genetically engineered technologies have aided in improving the effectiveness of PAHs' breakdown by microorganisms, creating and developing advanced bioremediation techniques. Optimizing the key characteristics like the adsorption, bioavailability, and mass transfer of PAH boosts the microorganisms' bioremediation performance, especially in the natural aquatic water bodies. This review's primary goal is to provide an understanding of recent information about how PAHs are degraded and/or transformed in the aquatic environment by halophilic archaea, bacteria, algae, and fungi. Furthermore, the removal mechanisms of PAH in the marine/aquatic environment are discussed in terms of the recent systemic advancements in microbial degradation methodologies. The review outputs would assist in facilitating the development of new insights into PAH bioremediation.