ABSTRACT
Biostimulation of polycyclic aromatic hydrocarbons (PAHs) is a major concern in the environment due to their toxic nature and ubiquitous occurrence. The study aimed to determine the best animal supplement of organic carbon source (cow dung, goat dung, pig dung and poultry (fowl droppings) and indigenous microbes capable of mineralizing pyrene in clay soil. Clay soil sample was collected from the top surface soil (0 - 15 cm) in Ikpoba River and upper Lawani river bank, both in Benin City with the aid of stainless steel trowel and gloved hands and stored in a polyethylene bag. The isolation and identification process were evaluated by staining method, microscopic examination and biochemical tests. The degradation experiment was conducted in bioreactors and supplemented cow dung, pig dung, goat dung and fowl droppings were added in varying amounts of 25 g/l, 50 g/l, 75 g/l and 100 g/l. The potential effects of animal organic carbon as nutrient supplements to enhance mineralization of pyrene were investigated. The rates of mineralization of pyrene were studied for a remediation period of 35 days at room temperature of about 25 °C. Results obtained from microbial isolation showed that B. substilis and A. niger were the most populated in the soil and were therefore selected. The degradation experiment showed that mixed culture of B. substilis and A. niger using 50 g/l supplement with the dungs and droppings gave the highest percentage degradation with fowl droppings 98.3%, pig dung 98.1%, goat dung 97.8%, and cow dung 97.7%. The least degradation was observed in supplement with 100 g/l in a single culture of A. niger with fowl droppings yielded 64.5% degradation, pig dung 63.8%, goat dung 63.7% and cow dung 62.7%. The overall results of the study showed that 50 g/l of animal wastes supplement in the ratio of 1:4 with pyrene contaminated soils are most effective in degradation processes. Also the mixed culture of bacteria and fungi enhanced pyrene mineralization and degradation more than single culture.
ABSTRACT
Normal color vision is a prerequisite for admission to the United States Naval Academy. The Farnsworth Lantern (FALANT) is the Navy's definitive test for color vision. A FALANT is not available at many locations where candidates are examined, so satisfactory performance on pseudoisochromatic plates has been considered an acceptable alternative. Until recently, the Farnsworth Dichotomous Test Panel D-15 had also been used as an alternative test, but is now considered unacceptable. In the summer of 1991, a large number of candidates reported for induction who were unable to pass the FALANT. Since their screening physical examinations had been reported to show normal color vision, a shadow of doubt was cast upon the ability of the alternative tests to predict performance on the FALANT. Four hundred subjects were then tested on several color vision tests to determine if these tests could predict FALANT success. The results of this study and recommendations are presented.
