Water quality in the Lachuá Ecoregion Landscape: Comparing streams from Forest, Milpa, and an Oil Palm plantation / Calidad del agua en el paisaje de la Ecorregión Lachuá: Comparando arroyos en bosques, milpa y palma africana

The hydrological network in the Lachuá Ecoregion (EL), Alta Verapaz, Guatemala, hosts high levels of biodiversity and supplies water to 44 Mayan communities. Despite this critical fact, this network has been threatened by scarcely monitored industrial activities including the rapidly expanding oil palm monoculture (Elaeis guineensisJacq). Regardless of Lachua's freshwaters importance, there is little information on how this monoculture impacts them. We compared water-quality properties from streams in oil palm plantations (P), paddock and milpa systems (M), and primary forests (F) in the EL. During 2015-2016, 13 rivers were sampled (5 times) for water temperature, pH, dissolved oxygen (DO), conductivity, hardness, chemical and biochemical oxygen demand (COD and BOD), and concentration of silica, nitrates, phosphates, and ammonia. Several parameters showed significant differences. P were 2.7 ºC and 1.8 ºC warmer than M and F and carried 1.4 mg/L more nitrates than F. F carried 10.8 mg/L and 11.8 mg/L more silica than M and P. M showed intermediate temperatures and silica concentrations, as well as 14.8 µS/cm and 8.9 µS/cm lower conductivities than P and F, respectively. Additionally, COD in M was 9.9 mg/L and 4.6 mg/L lower than P and F, respectively. We believe higher temperatures and lower silica in P are due to the loss of riparian forest and their role in buffering temperatures and recycling silicon. In addition, the existence of secondary forest (guamil) in M might explain the intermediate temperatures and silica concentrations. Our results highlight the contributions of forests to waterways and suggest potential water-quality depletion from the oil palm expansion in the EL.

La red hídrica en la Ecorregión Lachuá (EL), Alta Verapaz, Guatemala, alberga una alta biodiversidad y abastece de agua a 44 comunidades mayas. Sin embargo, recientemente se ha visto amenazada por actividades industriales escasamente monitoreadas, incluido el creciente monocultivo de palma africana (Elaeis guineensis Jacq) del cual se desconocen sus impactos en la EL. Este estudio explora la calidad del agua de arroyos en plantaciones de palma africana (P), bosques primarios (B), y sistemas de potrero y milpa (M) en Lachuá. Durante 2015-2016, se tomaron muestras de 13 ríos (5 veces) para medir la temperatura del agua, pH, oxígeno disuelto (OD), conductividad, dureza, demanda química y bioquímica de oxígeno (DQO y DBO) y la concentración de sílice, nitratos, fosfatos, y amoníaco. Varios parámetros mostraron diferencias significativas. P fue 2.7 ºC y 1.8 ºC más calientes que M y F y portó 1.4 mg/L más nitrato que F. F portó 10.8 mg/L y 11.8 mg/L más sílice que M y P. M mostró temperaturas y concentraciones de sílice intermedias y conductividades 14.8 µS/cm y 8.9 µS/cm menores que P y F. La DQO en M fue 9.9 mg/L y 4.6 mg/L menor que P y F. El aumento de temperatura y la disminución de sílice en P podría deberse a la pérdida de bosques ribereños los cuales amortiguan la tempe-ratura y reciclan el silicio. La presencia de bosque secundarios (guamil) en M podría explicar las temperaturas y las concentraciones de sílice intermedias resaltando la importancia de los bosques en la red hídrica. Se predice un posible deterioro en el agua resultado de la expansión de palma africana en la EL.

The influence of castanhão reservoir on nutrient and suspended matter transport during rainy season in the ephemeral Jaguaribe river (CE, Brazil) / Influência do açude Castanhão no transporte de nutrientes e materiais em suspensão durante a estação chuvosa no intermitente rio Jaguaribe (CE, Brasil)

Measurements of nutrient and suspended matter concentrations and loads entering and leaving the Castanhão reservoir during the rainy season were carried out to assess the influence of this large reservoir on land-sea fluvial transport in the ephemeral Jaguaribe river basin. Spatial variation indicated statistically significant attenuation of concentrations only for total phosphorous and suspended matter across the reservoir. Strong retention of nutrients and suspended matter loads by the reservoir was observed with average trapping efficiency of 89% for dissolved silicon, 98% of soluble reactive phosphorus, 71% for ammonium, 87% for total nitrogen, 98% for total phosphorus and 97% for suspended matter compared to the reservoir inflow. The dam operational procedure defined by the ephemeral conditions of the river reduced water releases compared to reservoir inflow and induced strong retention of nutrient and suspended matter loads within the reservoir when fluvial transfer occurs in this semiarid watershed.

Medidas de concentrações e fluxos de nutrientes e material particulado em suspensão de entrada e saída do Açude Castanhão foram efetuadas para determinar a influência de um grande reservatório no transporte fluvial entre o continente e o oceano na bacia hidrográfica intermitente do Rio Jaguaribe. A variação espacial indicou uma atenuação estatisticamente significativa ao longo do reservatório somente para as concentrações de fósforo total e material particulado em suspensão. Os resultados indicam uma forte retenção de nutrientes e do material particulado em suspensão com eficiências de retenção de 89% para sílica dissolvida, 98% para fósforo solúvel reativo, 71% para amônia, 87% para nitrogênio total, 98% para fósforo total e 97% para o material particulado em suspensão em relação aos fluxos de entrada no reservatório. A rotina de operação da barragem definida pela condição intermitente do Rio Jaguaribe reduz a descarga de água comparada com a entrada no reservatório e induz forte retenção do fluxo fluvial de nutrientes e material particulado em suspensão pelo reservatório.

A preliminary study of enamel remineralization by dentifrices based on RecaldentTM (CPP-ACP) and NovaMin® (calcium-sodium-phosphosilicate)

The purpose of this study was to investigate the enamel remineralization potential of two toothpastes, one of which was based on RecaldentTM (CPP- ACP) and the other on NovaMin® (Calcium-sodium-phosphosilicate). Human permanent molar teeth were subjected to three consecutive demineralization cycles. These cycles were followed by remineralization of the experimental groups by toothpastes containing RecaldentTM and NovaMin® respectively. The samples were analyzed by Scanning Electron Microscope, (SEM) and energy-dispersive X-ray spectroscopy analysis (EDX). Extensive demineralization was noted in the control group (without remineralization) while the groups treated with the dentifrices demonstrated various degrees of remineralization, as shown by formation of different types of deposits on the enamel surface. The EDX analysis showed increased amounts of Ca, P, Si and Zn in the enamel of the experimental groups, compared to the control one. Toothpastes containing RecaldentTM and especially NovaMin® have the potential to remineralize enamel, a property which might be important in finding a substitute to pit and fissure sealing.

El objetivo del trabajo fue investigar el potencial de remineralizacion del esmalte de dos pastas dentifricos, una de ella con formulacion basada en RecaldentTM (CPP- ACP) y la otra en NovaMin® (phosphosilicato de calcio y sodio). Se realizaron tres ciclos cosecutivos de desmineralizacion en molares permanentes humanos, seguidos de remineralizacion, en los grupos experimentales con los denti fricos que contenian RecaldentTM y NovaMin® respectivamente. Se analizaron las muestras con microscopia electronica de barrido (SEM) y analisis espectroscopico por dispersion de rayos X (EDX). En el grupo control (sin remineralizacion) se observo una extensa demineralizacion mientras que los grupos tratados con los dentifricos mostraron varios grados de remineralizacion, evidenciados por la formacion de diferentes tipos de depositos sobre la superficie del esmalte. El analisis EDX mostro cantidades aumentadas de Ca, P, Si y Zn en los grupos tratados en comparacion con el grupo control. Los dentifricos conteniendo RecaldentTM y especialmente Nova- Min®, tienen potencial de reminalizacion del esmalte, una propiedad que puede resultar importante como substituto del sellado de fosas y fisuras.

Determination of acid-resistant silicic particles in lung by micro-XRF and its application in diagnosis of drowning / 法医学杂志

OBJECTIVE@#Using microbeam X-ray fluorescence (Micro-XRF) analyzer for determination of acid-resistant silicic particles in lung, and to explore its potential application in diagnosis of drowning.@*METHODS@#Thirty two white rabbits were divided randomly into drowning group (n=12), post-mortem immersion group (n=10) and control group (n=10). Lungs and water sample were collected for determination of area concentration of acid-resistant silicic particles using Micro-XRF method.@*RESULTS@#The area concentration of acid-resistant silicic particles for the drowning water sample was 4.4 mm2/mL. For the lungs of drowning group, the post-mortem immersion group and the control group, the determined average values were (25.30 +/- 10.95) mm2/g, (1.68 +/- 0.63) mm2/g and (1.65 +/- 0.85) mm2/g, respectively, with a statistically significant difference between the drowning group and the other two groups.@*CONCLUSION@#The area concentration of acid-resistant silicic particles in lungs may be used as an indicator of drowning. The method is highly sensitive and rapid. It provides a potential application in drowning diagnosis.

Estimation of trace elements in sound and carious enamel of primary and permanent teeth by atomic absorption spectrophotometry: an in vitro study.

The influence of trace elements on the prevalence of caries is a complex subject. However, the demonstration of an inverse relationship between caries prevalence and fluoride (F) intake indicates the potential effect of trace elements on caries. AIMS AND OBJECTIVES: This in vitro study sought to estimate and compare the trace element concentrations in sound and carious enamel of primary and permanent teeth. MATERIALS AND METHODS: Forty sound and carious primary and permanent teeth, extracted from children and adolescents of Davangere city, were collected. The teeth were divided into four groups (of ten each) and enamel samples were prepared by mechanical grinding. The trace elements were estimated using atomic absorption spectrophotometer. RESULTS AND CONCLUSIONS: The results of our study showed the presence of 18 trace elements (F, Sr, K, Al, Si, Ni, B, Fe, Cu, Mn, Co, Cr, Zn, Mg, Se, Pb, Mo, and V) in the enamel of sound and carious primary and permanent teeth. The mean, standard deviation, and range (at 95% confidence level) were calculated for each element. The concentrations of F, Sr, and K were significantly ( P <0.05) higher in sound enamel of permanent teeth than in sound enamel of primary teeth. The concentrations of F, Sr, K, Al, and Fe were significantly ( P <0.05) higher in sound enamel of permanent teeth than in carious enamel of permanent teeth. The concentrations of F, K, and Si were significantly ( P <0.05) higher in sound enamel of primary teeth than in carious enamel of primary teeth.

Diurnal and spatial (vertical) dynamics of nutrients (N, P, Si) in four sampling days (summer, fall, winter, and spring) in a tropical shallow reservoir and their relationships with the phytoplankton community

Variações vertical, nictemeral e entre os dias de amostragem das formas de nitrogênio, fósforo e sílica solúvel reativa (SRS) foram estudadas no lago das Garças, reservatório tropical raso situado na cidade de São Paulo, sudeste do Brasil. Excetuado o N-NH4, todas as demais formas inorgânicas de nitrogênio (N-NO2, N-NO3 e N total) diminuíram de teor no sentido do fundo do reservatório. Da mesma maneira, todas as formas de nitrogênio apresentaram diferenças significativas quanto às horas de amostragem, aumentando seus valores durante a noite, em razão da ausência de fotossíntese nesse período. Essas formas diminuíram seus teores no dia de amostragem da primavera, graças à floração de Microcystis registrada nesse período. Os valores das três formas de fósforo estudadas (solúvel reativo, particulado e total) apresentaram variação vertical significativa, exceto no dia da amostragem de outono. No dia de amostragem de verão ocorreu aumento dos valores de P total e particulado, sendo que este último constituiu mais de 70% do P total durante todos os dias de amostragem. Considerando as horas, a variação dos teores de fósforo foi significativa nos dias das amostragem de primavera, de outono e de inverno. A variação vertical da sílica reativa solúvel foi significativa em todos os dias de amostragem, menos no da primavera. Essa variação também foi diferente entre as horas e os dias de amostragem.