Abstract： Excess of organic matter and nutrients in water promotes eutrophication process observed in the Ardila River. It was classified as much polluted being critical for Alqueva-Pedrogāo System. The aim of this ...Abstract： Excess of organic matter and nutrients in water promotes eutrophication process observed in the Ardila River. It was classified as much polluted being critical for Alqueva-Pedrogāo System. The aim of this study was to estimate the transported nutrients loads in a transboundary watershed using the SWAT （soil and water assessment tool） model and to determine the contribution of nutrients load in the entire watershed. Ardila watershed is about 3,711 km^2 extended from Spain （78%） to the eastern part of Portugal （22%）. It was discretized into 32 sub-basins using automated delineation routine, and 174 hydrologic response units. Monthly average meteorological data （from 1947 to 1998） were used to generate daily values through the weather generator Model incorporated in SWAT. Real daily precipitation （from 1931 to 2003） was introduced. The model was calibrated and verified for flow （from 1950 to 2000） and nutrients （from 1981 to 1999）. Model performance was evaluated using statistical parameters, such as NSE （Nash-Sutcliffe efficiency） and root mean square error （R2）. Calibration and verification flow results showed a satisfactory agreement between simulated and measured monthly date from 1962 to 1972 （NSE = 0.8; R^2 = 0.9）. The results showed that the most important diffuse pollution comes from the two the main tributary （Spain）. The estimated nitrogen and phosphorous loads contribution per year was respectively 72% and 59% in Spain and 28% and 41% in Portugal. The SWAT model was revealed to be a useful tool for an integrated water management approach that might be improved taking into count the WFD （water framework directive）.展开更多
Trophic status of some freshwater lakes all over the world, including Russia, Byelorussia, Japan, Sweden and China, has been assessed. The research submitted is based on the approach developed by OECD （Organization E...Trophic status of some freshwater lakes all over the world, including Russia, Byelorussia, Japan, Sweden and China, has been assessed. The research submitted is based on the approach developed by OECD （Organization Economic Cooperation and Development）. Annual total phosphorus averages formed a classification system. A probability assumption for each water body to reach some given trophic status was taken into account. Probability distribution curves for the average lake phosphorus have been analytically approximated.展开更多
The objective of this paper relies on the establishment of the sampling moment and the nutritional state of the species Conilon coffee （Coffea canephora） cultivated in Cambisoils. The effect of different rates of ni...The objective of this paper relies on the establishment of the sampling moment and the nutritional state of the species Conilon coffee （Coffea canephora） cultivated in Cambisoils. The effect of different rates of nitrogen fertilization was also studied in the leaves concentrations of N, at randomized complete block designs （N0= 0; N1 = 50; N2 = 100; N3 = 150 and N4 = 200 kg.ha^-1 of N） in presence of P （40 kg.ha^-1 of P2O5） and K （160 kg.ha^-1 of K2O）, with four replicates. The samples were carried out in the months of March （flower blossoming stage）, June （fruits growing stage）, September （grain development） and December （maturation） in all treatments. Foliar analysis carried out in the month of June （fruits growing stage） for the purpose of establishing critical nutrient range values for N, settling down approaches of interpretation of the same one for the Conilon coffee plantations on Cambisoils. The biggest percentages in the yields are obtained with leaves containing N between 2.80% and 3.10%, a value below 2.80% N which they associated with indicative percentages of stable maximum yield that did not surpass the limits of the adequate nutrients supply.展开更多
文摘Abstract： Excess of organic matter and nutrients in water promotes eutrophication process observed in the Ardila River. It was classified as much polluted being critical for Alqueva-Pedrogāo System. The aim of this study was to estimate the transported nutrients loads in a transboundary watershed using the SWAT （soil and water assessment tool） model and to determine the contribution of nutrients load in the entire watershed. Ardila watershed is about 3,711 km^2 extended from Spain （78%） to the eastern part of Portugal （22%）. It was discretized into 32 sub-basins using automated delineation routine, and 174 hydrologic response units. Monthly average meteorological data （from 1947 to 1998） were used to generate daily values through the weather generator Model incorporated in SWAT. Real daily precipitation （from 1931 to 2003） was introduced. The model was calibrated and verified for flow （from 1950 to 2000） and nutrients （from 1981 to 1999）. Model performance was evaluated using statistical parameters, such as NSE （Nash-Sutcliffe efficiency） and root mean square error （R2）. Calibration and verification flow results showed a satisfactory agreement between simulated and measured monthly date from 1962 to 1972 （NSE = 0.8; R^2 = 0.9）. The results showed that the most important diffuse pollution comes from the two the main tributary （Spain）. The estimated nitrogen and phosphorous loads contribution per year was respectively 72% and 59% in Spain and 28% and 41% in Portugal. The SWAT model was revealed to be a useful tool for an integrated water management approach that might be improved taking into count the WFD （water framework directive）.
文摘Trophic status of some freshwater lakes all over the world, including Russia, Byelorussia, Japan, Sweden and China, has been assessed. The research submitted is based on the approach developed by OECD （Organization Economic Cooperation and Development）. Annual total phosphorus averages formed a classification system. A probability assumption for each water body to reach some given trophic status was taken into account. Probability distribution curves for the average lake phosphorus have been analytically approximated.
文摘The objective of this paper relies on the establishment of the sampling moment and the nutritional state of the species Conilon coffee （Coffea canephora） cultivated in Cambisoils. The effect of different rates of nitrogen fertilization was also studied in the leaves concentrations of N, at randomized complete block designs （N0= 0; N1 = 50; N2 = 100; N3 = 150 and N4 = 200 kg.ha^-1 of N） in presence of P （40 kg.ha^-1 of P2O5） and K （160 kg.ha^-1 of K2O）, with four replicates. The samples were carried out in the months of March （flower blossoming stage）, June （fruits growing stage）, September （grain development） and December （maturation） in all treatments. Foliar analysis carried out in the month of June （fruits growing stage） for the purpose of establishing critical nutrient range values for N, settling down approaches of interpretation of the same one for the Conilon coffee plantations on Cambisoils. The biggest percentages in the yields are obtained with leaves containing N between 2.80% and 3.10%, a value below 2.80% N which they associated with indicative percentages of stable maximum yield that did not surpass the limits of the adequate nutrients supply.
