Search

Pollutants and microbiota present in the residual sludge of hydraulic fracturing were determined and characterized physicochemically. Analyses included determination of pH, electric conductivity, organic matter percentage, as well as total carbonates, inorganic nitrogen and extractable phosphorous. In addition, presence of hydrocarbons by gas chromatography, potentially toxic elements (PTEs) by atomic absorption and presence of radioactive isotopes by gamma spectrometry were determined. Moreover, fungi and bacteria present in the residual sludge were classified taxonomically to the level of genus. Medium and heavy hydrocarbon fractions were found in concentrations above the maximum limits permitted (MLP) by Mexican environmental norms. Cu, Pb, Zn, Fe and Mg, however, were below the MLP. Likewise, gamma spectrometry analysis revealed naturally occurring Ac228, Ra226 and K40. The microbiological analysis found presence of the bacteria Bacillus spp., Micrococcus sp., Diplococcus sp. and Staphylococcus sp. and the fungi Trichoderma sp., Aspergillus sp. and Penicillium spp. [ABSTRACT FROM AUTHOR]

Five samples of agricultural soil and five samples of Aloe barbadensis (P. Mill., 1768) plants with symptoms of wilt and root necrosis were collected in five localities of the state of Tamaulipas, México. The aims of this study were the morphological identification, molecular identification and in vitro evaluation of the antagonistic activity of Trichoderma spp. on Fusarium spp. Four strains of Trichoderma asperellum, one strain of Trichoderma harzianum and five strains of Fusarium oxysporum were identified by morphological and molecular methods. The evaluation of the antagonistic activity of T. harzianum isolate (TP) showed the highest inhibition in Fusarium spp. (78.80%). The evaluation of the antagonistic activity of Trichoderma spp. extracts in Fusarium spp. did not show significant differences between treatments (P ≤ 0.05), with Trichoderma growth percentages that oscillated between 81.08 and 94.38%. The native isolate of T. harzianum (TP) showed significant competitive capability against the mycelial growth of F. oxysporum. Trichoderma species are promising agents of biological control in the central area of the State Tamaulipas, Mexico. [ABSTRACT FROM AUTHOR]

Lophophora williamsii (peyote) is a spineless cactus that stands out for its psychoactive alkaloid content and considered vulnerable due to the destruction of its habitat and illegal extraction. The objective of this study is to describe the spatial distribution and interactions between facilitator species and L. williamsii that are important for this species conservation and reintroduction programs. The spatial distribution pattern was determined by Ripley's K-function. To know whether L. williamsii requires facilitator species, 10 plots of 100 m2 each were considered to perform dasometric measurements of the perennial species. Frequency of peyotes under the canopy of perennial species and open spaces was determined. The cardinal directions in which peyote individuals were found under the facilitator species were recorded, as well as soil surface temperature and solar radiation at soil level under the foliage and open spaces. L. williamsii showed an aggregated spatial distribution; 97.7% of peyotes were found under the foliage of facilitator species, where temperature and solar radiation were significantly lower than in the open spaces. Among the facilitator species, those that stand out are Flourensia cernua , Agave lechuguilla , Larrea tridentata , and Prosopis glandulosa. Significantly greater frequencies of peyotes were observed positioned on the northern quadrant of the facilitator crown. The results obtained show that L. williamsii needs the protection of perennial species for its establishment. Thus, the disappearance of these species could put at risk the persistence of peyote in these communities. These findings point out that the conservation and restoration of wild peyote populations require maintenance from the facilitator species. • Florencia cernua was the main facilitator species for Lophophora williamsii. • The highest L. williamsii density population is reported (7570 ind./ha). • Important data for future L. williamsii conservation and restoration planning. [ABSTRACT FROM AUTHOR]