Photodegradation is an important mechanism that affects carbon and nutrient cycling; a significant amount of data has been reported previously. The present review includes the effect of a wider spectrum of solar radiation (sun light, UV, and visible light) on plant litter decay in terrestrial ecosystems. Although the positive effect of photodegradation on decomposition is most common, a substantial number of studies reports contrasting results. Litter from 148 plant species, from 41 families, have been used in photodegradation studies, representing functional groups of trees (33%), graminoids (30%), shrubs (23%), forbs (11%), and peat (1%). Although the majority of studies focused on mass loss, a growing number focuses on nutrient release. Positive effects on mass loss are most common across different climate regions and laboratory studies, whereas “positive” influence and “no effect” on nitrogen and lignin release are equally common in temperate and sub-tropical environments. This may potentially be due to other decomposition processes which increase in relevance with increasing moisture and can facilitate microbial activity, leaching, and fractioning by soil fauna. In addition to climate region, initial litter quality influences photodegradation. Field-based and laboratory experiments frequently obtain contrasting results, suggesting that the mechanisms controlling the responses are unclear and might be dependent on several interactions, and/or the differences in experimental approaches (such as UV filters), or coverage by particles. Future research should focus on interactions between different factors, and on conducting experiments that test specific relationships such as the potential interaction between photodegradation, soil moisture, microbial communities, soil fauna, and their effects on litter decomposition (both mass loss and nutrient release). Furthermore, the topic would benefit from international studies applying the same experimental approach, as has successfully been conducted in other fields.

The study evaluated concentration, vertical distribution, and bioavailability of phosphorus fractions in the Indian Ocean core sediments. Sediment samples were collected from two sites in the Indian Ocean during January–February 2010 using gravity corer. Phosphorus fractions in sediments were analyzed by a modified sequential extraction procedure (SEDEX). The vertical profile revealed silt and clay as dominant grain size fractions in both cores. The enriched levels of organic carbon were observed in samples due to adsorption on fine grained sediments. Loosely bound P was the most dominant fraction, and its higher concentration in sediments was due to increased productivity and subsequent inputs of biogenic components. Detritus from marine organisms and lower oxygen concentrations (depletedE^hvalues) enhanced the production of authigenic P. The lower iron bound P fraction at specific depths was attributed to the nature of Fe minerals present within sediments. Decreased level of organic phosphate fraction was due to mineralization. The presence of Detrital P, the diagenetically stable form of P, might be due to inputs from the Himalayan, peninsular Indian, and Sri Lankan regions. The biogenic form was the dominant phosphate fraction throughout the cores suggesting the dissolution of fish debris. Estimated bioavailable phosphorous (BAP) ranged from 82.2 to 98.7% in Core I and from 90.21 to 92.98% in Core II, suggesting the fact that a major portion of the phosphate was bioavailable and hence the alterations in environmental conditions can release the BAP to water column resulting in nutrient enrichment.Graphical Abstract

This study aimed to investigate the quality and quantity of organic matter (OM) using biochemical components (protein, carbohydrate and lipids) in the sediment cores collected from the Central Indian Ocean (CIOB) under the program Equatorial Indian Ocean Process Study Dynamics and Biogeochemistry (EIOPS). Total organic carbon (TOC) and biochemical parameters (carbohydrate, lipid, protein, Tannin and lignin) were determined in core I and core II, respectively. Total carbohydrates varied from 4.66 to 2557.32 mg/kg (average 459.31 mg/kg) and 142.23 to 821.56 mg/kg (average 380.01 mg/kg) in core I and II, respectively. In core I, PRT varied from 70.95 to 107.05 mg/kg, and the minimum and maximum content of CHO was 143.23 and 822.56 mg/kg. The maximum and minimum concentrations of BPC in core II were 786.32 and 381.07 at 0–10 cm depth, respectively, which corresponded to the concentrations of PRT, CHO, LPD, and Tannin. The results showed that PRT was statistically significant with the TOC and negatively correlated with the LPD and CHO, while LPD was highly significant with clay and silt grains. In most of the samples, the ratio of LPD to CHO ratio was > 1, which indicated higher productivity of benthic organisms inhabiting the CIOB.

This pioneering study synthesises silver nanoparticles (AgNPs) using Carica papaya fruit extract and chitosan capping, yielding homogeneous, spherical nanoparticles prepared at an average size of 20 nm and characterised by SEM-EDAX and TEM. Antimicrobial activity studies showed that the opportunistic and human pathogenic ones, S. aureus, S. typhimurium and E. coli, were susceptible to the chitosan-capped AgNPs. This study signifies the novel synthesis approach, commensurate particle size, universal antimicrobial efficacy, and compilation of a comparative antibiotic resistance index. Chitosan-capped AgNPs acted effectively towards multidrug-resistant bacterial strains, which gives the opportunity to consider this material as a potential weapon in the fight against microbial infections, being eco-friendly.