The particle size analysis of soils and its use in forensic science--the determination of particle size distributions within the silt and sand fractions.
Methods are described for the determination of the particle size distributions in small soil samples using a Coulter Counter Model ZB for the silt fraction (60μm–2μm) and conventional sieving for the sand fraction (2mm–60μm). An examination of the reproducibility of the methods using duplicate 1·5g samples of eighteen different soils has shown that they are highly reproducible and that the differences between the soils were easily demonstrated both in the silt and sand particle distributions. The methods have also been shown to be reproducible for sample weights as low as 200mg of whole soil.
Evaluation of microbial soil identity in forensic science
SummaryMicrobiologic analysis of different soil samples was undertaken to assess the value of this method for forensic purposes. Three groups of micro-organisms were isolated on selective media: bacteria, fungi, and actinomycetes. Comparison of the morphology of the colonies led to the conclusion of non identity of the soil samples under examination. The method was applied to soil traces on articles of clothing, trousers, shoes, and stockings. It was found that the soil did not originate from the suspected scene of a crime. Examination of the microbiologic soil composition does not provide an absolute certainty of identity, but it is highly reliable.ZusammenfassungMikrobiologische Analysen verschiedener Bodenproben wurden durchgeführt mit dem Zweck, diese Methode für gerichtliche Untersuchungen zu überprüfen. Drei Gruppen Mikroorganismen des Bodens wurden auf selektiven Nährböden isoliert: Bakterien, Pilze und Aktinomyzeten. Durch den Vergleich der Morphologie der gewachsenen Kolonien konnte die Verschiedenheit der Bodenproben herausgefunden und bewiesen werden. Diese Methode wurde für sonstige Bodenspuren, die an Kleidungsstücken klebten, erfolgreich angewendet. Es konnte aus diesen Untersuchungen geschlossen werden, daß die Erde nicht von der Stelle, an der das Verbrechen vorausgesetzt wurde, herstammte. Die Untersuchungen hinsichtlich der mikrobiologischen Zusammensetzung von Bodenproben sind nicht absolut, aber sie sind bei kritischer Beurteilung sehr zuverlässig.
The Performance of Insecticides – A Critical Review
As part of minimizing the risk of crop losses due to herbivorous arthropods (here, mainly referring to insects and mites), most of the World’s commercial food production systems are subjected to several applications of pesticides before being harvested. Some crops are sprayed 10-20 times, while most field crops are sprayed 1-5 times during the growing sea‐ son. In the US alone, the average number of insecticide applications ranges from 1-3 for most of the major field crops, and the total annual costs of pesticide applications exceed $1.3 billion ([1], U.S. Department of Agriculture agricultural statistics services: www.nass.us‐ da.gov/). Several large ag-producing countries publish extensive details on insecticide use, including Australia, and the data presented below were collected from a public website (http://usda01.library.cornell.edu/usda/nass/AgriChemUsFruits//2000s/2008/AgriChemUs‐ Fruits-05-21-2008.pdf) on pesticide applications in the US in 2006. A somewhat extreme but also important example is the fresh sweet maize production in the US, which was grown on about 85,000 ha. Based on data from 14 US states, 20 different active ingredients of herbi‐ cides were applied an average 1.04 times to fresh sweet maize and amounted to about 2.6 kg of active ingredients of herbicides per ha. The same data suggested that about 3.5 kg of 23 different active ingredients of insecticides were applied on average 2.10 times per ha. Simi‐ larly, tomato fields (grown on about 42,000 ha in the US in 2006) were treated with 12 differ‐ ent active ingredients of herbicides, which were applied, on average, 1.14 times and the equivalent of about 0.7 kg of active ingredients per ha. Regarding insecticides, the same to‐ mato fields were treated with 32 different active ingredients, which were applied an average of 3.6 times and equal to about 4.9 kg of active ingredients per ha. While tomatoes and sweet corn may be close to the top of the list of growing crops receiving pesticide treatments, cau‐ liflower, celery, and many other horticultural crops and fruits are also subjected to intensive pesticide spraying regimes. Thus, farmers acknowledge that weeds and arthropods can po‐ tentially cause significant economic losses, and total pesticide application costs are low