RESUMO
Controlled land spreading of untreated olive mill wastewater (OMW) has been widely practiced as a means of its disposal. However, potential phytotoxic effects are critical for the selection of sites and crop types and for proper synchronization between land application and cropping. This study traced the fate of dissolved organic carbon (DOC), total phenols (TP), electrical conductivity, pH, microbial counts, and phytotoxicity to cress ( L.) after soil application at doses equivalent to 80, 160, and 320 m ha. Vertisol (fine-clayey) and Loess (sandy loam) soils were treated and incubated at 12 or 25°C and at moisture contents maintained at 70% of field water capacity or gradually reduced from 70 to 20% without compensation. Temperature, rather than moisture content, had a major effect on removal rates of DOC and TP. The maximum combined effect of warm temperature and higher moisture content resulted in removal rates greater than those under cooler, drier conditions by factors of up to 1.8 and 4.1 for DOC and TP, respectively. Favorable biodegradation conditions were indicated by increased numbers of total soil microorganisms and fungi by factors of up to 26 and 5, respectively. A whole-soil bioassay was developed to assess the dynamics of residual soil phytotoxicity after OMW application. Phytotoxicity measurement in soil extract generally showed stronger inhibition or stimulation activity than measurement in whole soil, depending on soil type and OMW dose. The newly developed bioassay seems to be useful for the refinement of general recommendations regarding permitted OMW application doses.
RESUMO
Field odor assessors are required to rate or describe several odor parameters, such as intensity, duration, offensiveness, and character. Ideally, their assessments should reflect the average odor perception of a specific community. The authors developed a three-part screening test for recruiting odor assessors: (1) distinguishing between different odorants by means of a triangular forced-choice test; (2) evaluating odor intensity; and (3) describing hedonic tone and odor character. Grading was based on two criteria: correctly answering the relevant parts of the test, and evaluation of odor parameters relative to the entire tested population. The latter involved grading each tested individual according to the similarity of their score to the average result of 179 tested individuals, comprising 48% women and 52% men whose age and residence distributions were identical between women and men (except for the oldest group). To exclude relatively less sensitive individuals who showed poor ability to distinguish between different odorants and various odor intensities, and/or provided atypical description (or rating) of odor intensity, character, and offensiveness, it was suggested that only individuals whose final score was within the upper 75% (final score +/- 80.75) would be qualified as odor assessors. According to this criterion, 73.8% of men and 78.6% of women passed the test. Among urban and rural dwellers, 77.4% and 67.4%, respectively, were qualified. Pass rate clearly diminished with increasing age: from 89.3% at 21-30 years to 54.6% at 61-70 years. This screening tool is recommended by the Israel Ministry of Environmental Protection for selection of field odor assessors to serve the general community and regulatory authorities.