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The results of the research related to the transformation of organic waste of different nature, through biodigester bales, are presented below.5 bales of approximately 1m3 were assembled with the following waste types: No0 (plant material), No1 (plant material+composting inoculum), No2 (plant material+Genesis®), No3 (plant material+goat manure), and No4 (plant material+coffee waste). The bales were made through non-probability sampling for convenience, because limited supply of waste at the time of the investigation (Pandemic). They were built with a 1t/m3 compaction system and monitored for 20 weeks, measuring height and temperature. Prior to its disassembly, samples were taken to determine the physicochemical composition, and organisms present. It was found that bale No. 0 was the one that presented the best behavior in terms of height, followed by bales 1, 2, 3, and 4, respectively. Bale No. 4 presented a better C/N ratio due to the high concentrations of organic carbon in coffee. It is concluded that the resulting material cannot be classified as organic fertilizer according to NTC 5167 of 2022, because not all the parameters comply. However, organic matter and major and minor elements are at optimal values to be classified as soils for agricultural crops. [ABSTRACT FROM AUTHOR]

A combined magnetic and geochemical analysis was carried out to identify the relationship between magnetic parameters, concentration of major elements and heavy metals in urban dust of Mexico City. Here, we propose simple mathematical models that can estimate the concentration of elements in urban dust by means of magnetic parameters, as well as establish the degree of precision of each model. Magnetic threshold values are also proposed to identify samples with low, medium and high concentrations of elements. Urban dust from Mexico City showed a different concentration of essentially ferrimagnetic minerals and superparamagnetic particles. The concentration of the elements in the urban dust samples were: Al between 3,325 to 27,336 mg kg-1; Cr between 17 to 117 mg kg-1; Cu between 15 to 405 mg kg-1; Fe between 653 to 39,217 mg kg-1; Ni between 21 to 66 mg kg-1; Pb between 27 to 366 mg kg-1; V between 11 to 52 mg kg-1 and Zn between 102 to 537 mg kg-1. The relationship between magnetic parameters and concentration of element is rather linear, showing positive Pearson correlation coefficients with values between 0.26 to 0.69. Magnetic threshold values were proposed to identify sites with relatively high accumulation of Cr, Cu, Ni, Pb and Zn. These values for specific magnetic susceptibility are: Low < 2.86 µm3 kg-1; Moderate: 2.86 to 3.46 µm3 kg-1 and High > 3.46 µm3 kg-1; and for remanent isothermal magnetization of saturation: Low < 38 mAm2 kg-1; Moderate: between 38 to 46 mAm2 kg-1 and High > 46 mAm2 kg-1. Mathematical models to estimate the concentration of elements showed effectiveness of about 60%. [ABSTRACT FROM AUTHOR]

Because the genus Puya is one of the most important food resource for Andean bears, the nutritional content of its leaves might be important for choosing the individuals, species or quantity in order to meet the bear's nutritional requirements. The objective of this research was to compare whether or not there are differences between mature and young leaves of two Puya species (Puya goudotiana and Puya santosii) in the paramo ecosystems of the Guavio Region, Colombia. Two leaves per individual were collected from the base of the leaf. Soil samples were also collected in each sample point in order to evaluate if soil related to leaf nutrient content. Results showed marked differences between species. P. goudotiana exhibited the highest concentrations of all elements except for calcium. Also, significant differences were found between conspecific mature and young leaves. The latter showed higher values of phosphorus, potassium and nitrogen, meanwhile mature leaves were higher in calcium. No relationship between soils chemical composition and leaf nutrient content was found. The reasons for these differences and the consequences in the Andean bear diet are discussed. [ABSTRACT FROM AUTHOR]