Factors affecting dissolved phosphorus and nitrate concentrations in ground and surface water for a valley dairy farm in the northeastern United States.

Agriculture often is considered to be a contributor of soluble reactive phosphorus (SRP) and nitrate-N (NO3- -N) to surface waters. This research analyzed SRP and NO3- -N concentrations in groundwater and in a creek fed by groundwater on a valley dairy farm in the Cannonsville basin of the New York City (NYC) watershed. A total of 37 groundwater piezometers were installed to depths of 0.3 to 1.5 m. Water-table depth and concentrations of SRP, NO3- -N, dissolved organic carbon (DOC), and dissolved oxygen were measured at regular intervals over a three-year period. A multivariate mixed model analysis of variance indicated that the SRP and NO3- -N concentrations were controlled primarily by three classes of variables: environmental variables, including precipitation and water table depth; source variables, including manure applied and crop type; and chemical variables, including DOC and dissolved oxygen concentrations in groundwater. The highest groundwater concentrations of N03- -N and SRP were found at the shallowest water-table depths, which has implications for agricultural nutrient management in areas with shallow groundwater.

[Lipid profile in household contacts of patients with pulmonary tuberculosis]. / Perfil de lípidos en contactos convivientes de pacientes con tuberculosis pulmonar.

BACKGROUND: we have recently published the hypothesis that hypocholesterolemia might be a risk factor for the development of pulmonary tuberculosis. In this sense, albeit patients with pulmonary tuberculosis often have total cholesterol levels lower than the general population, it is not known if the latter have had a recent exposure to Mycobacterium tuberculosis. OBJECTIVE: to evaluate serum lipids in subjects exposed to mycobacteria. METHODS: we studied 25 pulmonary tuberculosis patients and 44 household contacts, and compared their serum lipid profile. RESULTS: We found that total cholesterol, LDL and triglycerides concentrations increased with age in contacts but not in pulmonary tuberculosis patients, with statistically significant differences in regression lines (age versus lipid level). Multiple linear regression analysis confirmed that being a household contact was associated with higher levels of total cholesterol, LDL, HDL and triglycerides. CONCLUSIONS: We conclude that lipid profile differed between pulmonary tuberculosis patients and their household contacts, thus supporting that low cholesterol levels might be a risk factor for developing pulmonary tuberculosis.