Heavy metals and trace elements analysis in groundwater around Mahaoya hot water springs

Groundwater in and around Mahaoya thermal springs found in the Precambrian highgrade metamorphic terrain of Sri Lanka were investigated to assess their geochemical properties with compared to normal regional groundwater of particular area and to produce a data set to develop a model of identification of thermal springs or mixing of thermal and non-thermal ground water. The main objective is this study is to compare the geochemical parameters of thermal springs with nearby cold ground water and interprets the geochemical relationships among them.Samples of low temperature (<35 °C) groundwater from nearby springs, piezometers and open wells were also collected for comparison. All samples were analyzed for their major and trace element compositions using Atomic Absorption Spectrophotometer and standard methods.These waters showed low concentrations of selected trace elements and were comparable to that of geothermal groundwater. Major cation and anion concentrations of thermal springs are similar to nearby cold springs. Close matches of geochemical data from geothermal and dug wells waters confirm the hypothesis of a common source

Produção de batata-doce em função de doses de P2O5 em dois sistemas de cultivo Yield of sweet potato affected by P2O5 levels in two planting systems

Com o objetivo de avaliar o efeito da adubação fosfatada e de sistemas de plantio na produção total e comercial de raízes de batata-doce, cv. Rainha Branca, conduziu-se um experimento, de fevereiro a julho de 2003, na UFPB, em Areia (PB). O delineamento experimental foi de blocos casualizados com os tratamentos distribuídos em esquema fatorial 5 x 2, com os fatores doses de fósforo (0; 100; 200; 300 e 400 kg de P2O5 ha-1) e sistemas de plantio (uma e duas ramas por cova), em quatro repetições. As produções total e comercial de raízes de batata-doce, em resposta as doses de fósforo no sistema de plantio com uma rama por cova, foram de 21,6 e 18,7 t ha-1, obtidas com 237 e 210 kg de P2O5 ha-1, respectivamente. No sistema de plantio com duas ramas por cova, essas produções foram de 23,5 e 18,9 t ha-1, alcançadas com 259 e 231 kg de P2O5 ha-1, respectivamente, enquanto as doses econômicas para a produção de raízes comerciais, foram 173 e 194 kg de P2O5 ha-1, para os sistemas de plantio com uma e duas ramas, respectivamente. No sistema de plantio com uma rama e dose econômica correspondeu a 82% daquela para a máxima eficiência técnica (MET) e para o sistema de duas ramas a 84% da MET, constituindo um indicativo da viabilidade econômica do emprego de fósforo no cultivo da batata-doce. As doses de fósforo estimadas que resultaram nas máximas produções de raízes comerciais e retornos econômicos, quanto ao sistema de plantio com uma e duas ramas por cova corresponderam, respectivamente, com 21 e 19 mg de P disponível dm-3, extraído pelo extrator de Melich 1. Em solos semelhantes ao deste estudo, a adubação fosfatada na batata-doce poderá ser dispensada, quando os teores de fósforo disponível forem superiores a 19 e 20 mg dm-3 de solo, respectivamente, para os sistemas de plantio com uma e duas ramas por cova.<br>The influence of phosphate fertilization and planting systems were evaluated on the yield and quality of sweet potato roots, Rainha Branca cv. The experiment was carried out from February to July/2003 in a Quartz Psamment soil in Paraiba State, Brazil. The experimental design was of randomized blocks with four replications. Treatments were distributed in a 5 x 2 factorial design, with five levels of P2O5 (0; 100; 200; 300 and 400 kg ha-1 ) and two planting systems (one and two stems/hole). Total and commercial sweet potato roots production, in response to P2O5 levels with one stem/hole, were 21.6 and 18.7 t ha-1 obtained with 237 and 210 kg ha-1 of P2O5, respectively. Using two stems/hole, 23.5 and 18.9 t ha-1 were obtained when 259 and 231 kg of P2O5, were employed, respectively. Levels of 173 and 194 kg of P2O5 applied for one and two stems/hole, respectively, were economically viable for the commercial roots production. The economical level in the planting system using one stem/hole, was 82% of the technical maximum efficiency (TME) and for two stems/hole was 84% TME being an indicative of economical viability of phosphorus application in sweet potato. P2O5 levels that resulted in maximum production and economical returns for commercial roots for planting systems with one and two stems/hole were 21 and 19 mg dm-3 of phosphorus available, using Melich-1 extractor. In similar soil types for commercial roots production, the phosphate fertilization will be dispensed, when available phosphorus levels were higher than 19 and 20 mg dm-3 of soil in planting systems with one and two stems/hole