Cations extraction of sandy-clay soils from Cavado valley, Portugal, using sodium salts solutions

Cases of contamination by metals in the water wells of the Cavado Valley in north-west Portugal can be attributed to the heavy leaching of clay soils due to an excess of nitrogen resulting from the intensive use of fertilisers in agricultural areas. This work focuses on the natural weathering characteristics of soils, particularly the clay material, through the study of samples collected near the River Cavado. Samples taken from various sites, after physico-chemical characterisation, were subjected to clay dissolution tests, using sodium salts of different ionic forces, to detect the relationship between certain physico-chemical parameters of water, such as pH, nitrate, chloride and sulphate content, in the dissolution of clay and the subsequent extraction of such cations as Al, Fe and K. In acidic sandy clay soils, the mineralogical composition of which was characterised by a predominance of quartz, micas, kaolinite and K-feldspars, decreases of the clay material/water pH ratio increases dissolution of the micaceous and K-feldspars phases. The presence of nitrates in the aqueous solution apparently advanced the extraction of all three cations Al, Fe and K. The specific surface area of the clay material showed a significant correlation with the main kinetic parameters of cation extraction.Têm ocorrido casos de contaminações de águas de poços, por metais, no vale do Rio Cávado, região noroeste de Portugal. A princípio, poderiam ser explicáveis pela elevada lixiviação dos solos arenoargilosos da região, quando da prática de adubações intensivas de nitrogênio em áreas agrícolas. Assim, estudaram-se as características do intemperismo natural dos solos, particularmente da fração argila, característica da margem norte do rio Cávado. Coletaram-se amostras de vários locais, que foram submetidas, após caracterização físico-química, a ensaios de dissolução a partir de soluções de sais de sódio com diferentes forças iônicas. O objetivo foi observar as relações de determinados parâmetros físico-químicos da água, tais como: pH, nitratos, cloretos e sulfatos na dissolução das argilas e a conseqüente extração de espécies químicas tais como Al, K e Fe. Para solos areno-argilosos, ácidos, cuja composição mineralógica se caracteriza por um predomínio de quartzo, micas, caulinita e feldspato-K, o abaixamento do pH da suspensão solo/água promove a solubilização das fases micáceas e feldspáticas. A presença do nitrato nas soluções aquosas promoveu aparentemente a extração de todos os três cátions: Al, K e Fe. O efeito da área superfícial específica das partículas dos solos condicionou fortemente vários dos parâmetros cinéticos estudados relativos à extração dos cátions.(undefined

University teachers’ self-reflection on their academic growth

This study followed the academic growth of four university teachers, over a two-year period, with the intention of enhancing inquiry-based learning in practice. Data were generated within the natural settings of classrooms, laboratories and lecture halls, through the analysis of teaching materials, low-participation observation, informal discussions and semi-formal interviews. The research approach was based on a critical social paradigm, assuming principles of action-research methodology privileging a transitional ‘instructional coaching approach’. Outcomes show a marked interest in the design and development of innovative approaches to teaching, learning, feedback and assessment. They demonstrated strong collaborative practices, insightful reflections on their teaching activities, and willingness to share evaluations both within and without of university contexts and successfully contributing thoughts and ideas to a wider audience.This research was financed by European Founds ‘FEDER através do Programa Operacional Factores de Competitividade – COMPETE’ and by National Funds through ‘FCT – Fundação para a Ciência e a Tecnologia’ project PTDC/CPE-CED/117516/2010

Question Asking During Reading Comprehension Instruction:A Corpus Study of How Question Type Influences the Linguistic Complexity of Primary School Students’ Responses

The authors examined teachers’ (N = 19) use of different question types during small‐group comprehension instruction for 6–11‐year‐olds (N = 115). The authors tagged the corpus of 40 hours of guided reading sessions to enable computer‐based searches for syntactic forms of questions. Teachers frequently asked high‐challenge wh‐ word questions (e.g., “How does that fit in with what you just read?”), and this was more pronounced in schools located in regions of low socioeconomic status, a finding associated with recency of completion of teacher training. Students’ responses were more linguistically complex when teacher questions comprised a high frequency of high‐challenge questions, particularly wh‐ word adverb questions (predominantly why and how). These findings applied across the wide age and ability range of the sample, indicating that high‐challenge questions are effective in small‐group comprehension instruction for students in different age groups and at various levels of reading ability. The authors conclude that teachers benefit from being informed about the effect of various syntactic forms of questions, particularly the nuances of wh‐ word questions. The findings also highlight the advantages of using corpus search methods to examine the influence of teacher question‐asking strategies during classroom interactions