Impacts of manganese mining activity on the environment: interactions among soil, plants, and arbuscular mycorrhiza.

The mining district of Molango in the Hidalgo State, Mexico, possesses one of the largest deposits of manganese (Mn) ore in the world. This research assessed the impacts of Mn mining activity on the environment, particularly the interactions among soil, plants, and arbuscular mycorrhiza (AM) at a location under the influence of an open Mn mine. Soils and plants from three sites (soil under maize, soil under native vegetation, and mine wastes with some vegetation) were analyzed. Available Mn in both soil types and mine wastes did not reach toxic levels. Samples of the two soil types were similar regarding physical, chemical, and biological properties; mine wastes were characterized by poor physical structure, nutrient deficiencies, and a decreased number of arbuscular mycorrhizal fungi (AMF) spores. Tissues of six plant species accumulated Mn at normal levels. AM was absent in the five plant species (Ambrosia psilostachya, Chenopodium ambrosoides, Cynodon dactylon, Polygonum hydropiperoides, and Wigandia urens) established in mine wastes, which was consistent with the significantly lower number of AMF spores compared with both soil types. A. psilostachya (native vegetation) and Zea mays showed mycorrhizal colonization in their root systems; in the former, AM significantly decreased Mn uptake. The following was concluded: (1) soils, mine wastes, and plant tissues did not accumulate Mn at toxic levels; (2) despite its poor physical structure and nutrient deficiencies, the mine waste site was colonized by at least five plant species; (3) plants growing in both soil types interacted with AMF; and (4) mycorrhizal colonization of A. psilostachya influenced low uptake of Mn by plant tissues.

Assessing sustainability in North America's ecosystems using criticality and information theory.

Sustainability is a key concept in economic and policy debates. Nevertheless, it is usually treated only in a qualitative way and has eluded quantitative analysis. Here, we propose a sustainability index based on the premise that sustainable systems do not lose or gain Fisher Information over time. We test this approach using time series data from the AmeriFlux network that measures ecosystem respiration, water and energy fluxes in order to elucidate two key sustainability features: ecosystem health and stability. A novel definition of ecosystem health is developed based on the concept of criticality, which implies that if a system's fluctuations are scale invariant then the system is in a balance between robustness and adaptability. We define ecosystem stability by taking an information theory approach that measures its entropy and Fisher information. Analysis of the Ameriflux consortium big data set of ecosystem respiration time series is contrasted with land condition data. In general we find a good agreement between the sustainability index and land condition data. However, we acknowledge that the results are a preliminary test of the approach and further verification will require a multi-signal analysis. For example, high values of the sustainability index for some croplands are counter-intuitive and we interpret these results as ecosystems maintained in artificial health due to continuous human-induced inflows of matter and energy in the form of soil nutrients and control of competition, pests and disease.

Prevalencia y factores de riesgo de colelitiasis en pacientes menores de 18 años en un hospital de segundo nivel / Prevalence and risk factors for cholelithiasis in patients under 18 years of age at a second level health care hospital

Objetivo: Observar la prevalencia de litiasis vesicular y factores de riesgo en menores de 18 años, en un hospital de segundo nivel. Sede: Hospital General de Matamoros ''Dr. Alfredo Pumarejo Lafaurie'', Tamaulipas. Diseño: Estudio retrospectivo, transversal, observacional, descriptivo. Análisis estadístico: Porcentajes como medida de resumen para variables cualitativas. Pacientes y métodos: Se revisaron 706 expedientes clínicos de pacientes con diagnóstico de colelitiasis en un periodo comprendido entre enero de 2003 a diciembre de 2008. Las variables estudiadas fueron: edad menor de 18 años, sexo, antecedentes familiares de litiasis vesicular, enfermedades hemolíticas, uso de hormonales, embarazos, índice de masa corporal, síntoma predominante, complicaciones (coledocolitiasis y pancreatitis), tiempo de estancia hospitalaria y estudio histopatológico vesicular. Resultados: Se identificaron 26 casos con edad promedio de 12.8 años, todas mujeres, 16 pacientes (61.5%) con antecedente de embarazo. Sólo una paciente presentó peso normal, sobrepeso en siete pacientes, obesidad grado l en ocho pacientes, grado II en seis pacientes, grado III en cuatro pacientes, el 100% con antecedentes de litiasis vesicular materna. Conclusión: La prevalencia de colelitiasis en menores de 18 años fue de 3.6%. Los factores de riesgo asociados a pacientes mayores de 18 años fueron similares en la población estudiada menor de 18 años.

Objective: To observe the prevalence of gallbladder lithiasis and risk factors in patients under 18 years in a second level health care hospital. Setting: General Hospital of Matamoros ''Dr. Alfredo Pumarejo Lafaurie'', Tamaulipas. Mexico. Design: Retrospective, cross-sectional, descriptive, observational study. Statistical analysis: Percentages as summary measure for qualitative variables. Patients and methods: We reviewed 706 clinical files of patients with choledocholithiasis diagnosed between January 2003 and December 2008. Studied variables were: age below 18 years, sex, familial antecedents of gallbladder lithiasis, hemolytic diseases, use of hormones, pregnancies, body mass index, predominating symptom, length of in-hospital stay, and histopathological study of the gallbladder. Results: We identified 26 cases with an average age of 12.8 years; all were women, 16 patients (61.5%) with antecedents of pregnancy. Only one patient had a normal weight, seven patients were overweight, eight patients coursed with obesity grade I, six with grade II, and four with grade III. All (100%) had antecedents of maternal gallbladder lithiasis. Conclusion: Prevalence of choledocholithiasis in patients under 18 years of age was of 3.6%. Associated risk factors for patients below 18 years of age are similar to those encountered over 18 years of age.

Efecto de la adición de zeolita (clinoptilolita y modernita) en un andosol sobre el ambiente químico edáfico y el crecimiento de avena / Effect of zeolite (clinoptilolite and mordentite) amended andosols on soil chemical environment and growth of oat

Entre las zeolitas, la clinoptilolita y la mordenita se distinguen por su utilidad en la agricultura, debido a que al entrar en contacto con el amonio del medio lo retienen en su estructura interna y externa, funcionando entonces como un fertilizante nitrogenado de lenta liberación. Se estudió el efecto de la zeolita ZCU (clinoptilolita y mordenita) en la producción de biomasa vegetal y el ambiente químico del suelo, empleando la avena como cultivo indicador. Se evaluaron cinco concentraciones de ZCU en suelo (0, 5, 10, 20 y 30 por ciento peso base seca del suelo) y un tratamiento adicional preparado solo con ZCU. Las variables evaluadas fueron biomasa aérea y de raíces, pH y capacidad de intercambio catiónico (CIC), NH4+ sustrato y NO3-l lixiviado. La aplicación de ZCU tuvo un efecto positivo sobre la producción de la biomasa aérea y de raíces y modificó el ambiente químico edáfico en sus valores de pH y CIC. La aplicación de ZCU provocó una menor acumulación de NO3- lixiviado en relación a la cantidad de NH4+ en sustrato. Los resultados apoyan que la ZCU tiene capacidad para adsorber amonio y aminorar el proceso de nitrificación.