No abstract

A useful extraction for humic acid from anaerobic municipal solid‐waste landfill leachate is presented. Extraction was accomplished by adding NaOH pellets to give a 0.57N NaOH solution under an N2 atmosphere. The separation of the humid and fulvic acid fractions was carried out using Matricel type filters (0.45‐µm pore size diam). The infrared characterization of leachate humic acids was markedly improved in time and sample‐size‐requirement reductions by using a Matricel filter made out of a PVC copolymer as a support for these acids. The results obtained compared very favorably with the infrared KBr pellets. The infrared spectra of leachate humic acids proved to be similar to the lake‐ooze humic acid spectra reported by Stevenson and Goh (1971). Humid substances represent > 60% of the total organic C found in anaerobic landfill leachates. Fulvic acid predominates in young unstable leachates, and decreases in concentration with age. Humic acids increase with the age of the leachates, eventually decreasing as the leachate becomes more stable and diluted.

Saturated hydraulic conductivities and intrinsic permeabilities were evaluated for eight contrasting soils with four organic liquids and water. The organic liquids were kerosene, ethylene glycol, isopropyl alcohol and xylene. Intrinsic permeability for any given soil varied inversely with the dielectric coefficient -water gave the lowest value. The mechanism is apparently related to the double-layer phenomena with water leading to the most dispersed system.A multiple regression analysis related intrinsic permeability to silt, dielectric coefficient, clay and bulk density with a goodness of fit (R) of 0.74. An analysis of all the non-aqueous liquids, with water permeability as a dependent variable, resulted in an R of 0.84. The study has relevance with regard to movement of such organics in soils either as a pollutant or as a solvent carrying pollutants.

Semiarid desert algal crust organisms were found to fix N2 when exposed to an atomosphere which contained isotopically enriched N. Significant quantities of the N isotope were detected in the total crust N after 3 days of incubation under field‐simulated conditions. Net N2 fixation rates by the algal crust organisms were 0.16 and 0.10 lb of N/acre of crust surface per day under continuous wet and cycling wet‐dry conditions, respectively. Net fixation of N under field‐simulated conditions adequately compensated for the removal of N by livestock. The rate of N2 fixation under field‐simulated conditions increased linearly for at least 520 days. The amount of N in the algal crust was doubled during this time. No net N change was observed in dry crusts. Growing algal crusts contained 1% to 2% of the total N as extracellular NH4‐N. Excretion of some fixed nitrogen was suggested by the isotopic enrichment of the extracellular N fraction and uptake of labeled N by grass seedlings (Artemesia sp.) growing on incubated crusts.

A large proportion of phosphorus of crop residues was found to be readily available to succeeding crops. Some of the factors that influence the rate of release of phosporus from plant residues added to soils for use by succeeding plants were studied. They were: (a) maturity of the crop residue, (b) phosphorus content of the residue, (c) rate of application of the residues, (d) time of contact of the crop residue with the soil, (e) kind of crop residue, and (f) plant part involved. The study was conducted under greenhouse conditions in large glazed pots that held 1 kg. or more of soil. The influence of the above factors on the utilization of phosphorus by several test crops is less pronounced in soils well supplied with available phosphorus than in soils low in available phosphorus. The rate of availability of the phosphorus of the crop residues to the test crops, ryegrass and tomato, was inversely related to the stage of growth of the residues. For example, green manures cut prior to blooming supplied plants with about as much phosphorus as did liquid H3PO4 fertilizer. The phosphorus of straw, on the other hand, was absorbed by plants to a lesser extent than that of the liquid H3PO4. The phosphorus of residues high in total phosphorus was more readily available to plants than was that of residues low in phosphorus. The threshold phosphorus content of the crop residue above which the phosphorus of the residue was not wholly immobilized by microorganisms for use in decomposition was found to be about 0.2%. Phosphorus from root residues was less readily available than that from top residues only if the residues came from fully mature plants.