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1.
Environ Pollut ; 327: 121449, 2023 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-36963458

RESUMO

The fate of suspended solids in aqueous systems enriched with copper (Cu) and arsenic (As) is still poorly understood, especially in mildly acidic streams with natural turbidity. This study integrated field, laboratory, and modeling to determine how turbidity, particle size distribution, and the partition of Cu and As interact in two model river confluences in an Andean watershed (upper Elqui, North-Central Chile). The mildly acidic Toro River (40.4 mgL-1; CuTOTAL>8 mgL-1) was diluted and neutralized at two consecutive confluences, resulting in dissolved As and Cu lower than 0.04 and 0.1 mgL-1, respectively. On-site laser scattering measurements showed that the size of suspended sediments was dominated by ultrafine (d<6 µm) and fine (6200 µm) were not observed, contrasting with other reactive Andean confluences that work as natural coagulation-flocculation reactors. Laboratory mixing experiments with filtered endmembers followed closely the trends observed in the field measurements. SEM observations and thermodynamic calculations, suggested that As-rich amorphous Fe minerals dominated the fine suspended solid inflow (d<15 µm) from the Toro River, while XRD did not reveal significant amounts of crystalline forms of Fe, As, or Cu minerals. Despite fresh precipitates that further associated dissolved As and Cu, the particles from the Toro River grew only slightly after the confluences, thus limiting particle settling potential and a significant metal-(loid)s removal. Consequently, the seasonal variation in the size and chemical nature of suspended solids in acid drainage inflows control the distinct physical and chemical fates of As and Cu after neutralization, as well as hydrodynamic or hydraulic conditions likely also constrain sediment deposition. The combined monitoring of chemical parameters and particle size distributions is a simple and cost-effective method to obtain information about the behavior of metal(loid)s and sediments.


Assuntos
Arsênio , Poluentes Químicos da Água , Cobre/análise , Arsênio/análise , Tamanho da Partícula , Poluentes Químicos da Água/análise , Metais/análise , Minerais , Rios/química , Água , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química
3.
Rev Med Chil ; 118(3): 247-52, 1990 Mar.
Artigo em Espanhol | MEDLINE | ID: mdl-2131502

RESUMO

Two hundred and sixty five subjects with high risk works for leptospirosis were submitted to microscopic agglutination test for leptospira. 122 worked at animal farms, 71 in rice growing fields and 72 in slaughter houses. 30 control subjects were also tested. A total of 66 samples (22%) were positive, most of them with low titers. Percentage of positive reactions were higher for persons working in rice fields, followed by those working in slaughter houses and animal farms. The 21-40 year age group was most affected in all working sites. Serovars found most commonly were ichterohemorrhagic in rice field workers, hardjo and ballum in slaughter houses and pomona and hardjo in animal farms.


Assuntos
Doenças dos Trabalhadores Agrícolas/epidemiologia , Leptospirose/epidemiologia , Adolescente , Adulto , Idoso , Testes de Aglutinação , Doenças dos Trabalhadores Agrícolas/diagnóstico , Doenças dos Trabalhadores Agrícolas/etiologia , Animais , Chile/epidemiologia , Inquéritos Epidemiológicos , Humanos , Leptospirose/diagnóstico , Leptospirose/etiologia , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Estudos Soroepidemiológicos
7.
Bol. Hosp. San Juan de Dios ; 30(6): 318-22, 1983.
Artigo em Espanhol | LILACS | ID: lil-19729

RESUMO

Se presentan los resultados de un estudio de prevalencia de bocio en una area endemica (Alhue). Se examinaron 556 escolares basicos de ambos sexos (72.7% de la poblacion escolar); encontrandose una prevalencia de 36.2% (201 casos). La cifra mas alta se observo en Hacienda Alhue: 44.9% (22 casos) y la mas baja: 23.5% (4 casos) en Polulo. Entre las mujeres se observo una prevalencia de 39.9% (110 casos) y una de 32.5% (91 casos) entre los hombres (diferencia no significativa). Los grados mas frecuentes de bocio fueron Ia (99 casos) 7.8% y Ib (94 casos); 16.9%. El sexo femenino presento frecuencias mayores aunque no significativas de bocio de todos los tipos. Basados en estudios anteriores se concluye que la situacion regional no ha mejorado en tres decadas. Se formulan recomendaciones para el estudio y control del problema


Assuntos
Pré-Escolar , Criança , Adolescente , Humanos , Masculino , Feminino , Bócio Endêmico , Inquéritos Epidemiológicos , Chile
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