Most drinkable water supplied to the public in Mexico City comes from deep wells which extract water from the subsoil. Before being distributed, it is treated in steel filtration tanks. This water must be subject to e...Most drinkable water supplied to the public in Mexico City comes from deep wells which extract water from the subsoil. Before being distributed, it is treated in steel filtration tanks. This water must be subject to evaluation through physic-chemical and bacteriological analyses in order to determine its quality. However, doubts always remain over the influence of the components of this water on the corrosive behavior of the filtration tanks. In light of this, this article studies the physic-chemical characterization values of water and presents the results. This has also enabled the analysis of the corrosion speed of filtration tanks components, boilers and water-cooled systems, where incrustations in pipes, obstructions and loss of heat transfer efficiency occur, rendering drinkable water bad tasting and, after some time, causing pitting corrosion although this type of corrosion only causes serious problems in the long term.展开更多
Soil plays an important role in desert ecosystem, and is vital in constructing a steady desert ecosystem. The management and restoration of desertified land have been the focus of much discussion. The soil in Shapotou...Soil plays an important role in desert ecosystem, and is vital in constructing a steady desert ecosystem. The management and restoration of desertified land have been the focus of much discussion. The soil in Shapotou desert region has developed remarkably since artificial sand-binding vegetation established in 1946. The longer the period of dune stabilization, the greater the thickness of microbiotic crusts and subsoil. Meanwhile, proportion of silt and clay increased significantly, and soil bulk density declinced. The content of soil organic matter, N, P, and K similarly increased. Therefore, soil has developed from aeolian sand soil to Calcic-Orthic aridisols. This paper discusses the effects brought about by dust, microbiotic soil crust and soil microbes on soil-forming process. Then, we analyzed the relation between soil formation and sand-binding vegetation evolution, in order to provide a baseline for both research on desert ecosystem recovery and ecological environment governance in arid and semi-arid areas.展开更多
To assess the impact of land use on the Andosol fertility, changes in chemical and physical properties affecting soil quality were monitored on Andosols from Mount Bambouto submitted to four different land use and man...To assess the impact of land use on the Andosol fertility, changes in chemical and physical properties affecting soil quality were monitored on Andosols from Mount Bambouto submitted to four different land use and management systems: natural cover, tillage, burning and fallow. In comparison with the natural cover, tillage reduces Andosol OC (6.5 to 4.8%), total N (4.51 to 2.95‰), CEC (22.0 to 20.9 cmol.kg–1) and the abundance of soil macro-aggregates expressed by the water stable aggregates (WSA) varies from 53.8 to 12.0%;and increases the bulk density (0.69 to 1.09 g.cm–3) and the sum of exchangeable cations (3.58 to 4.84 cmol.kg–1). Burning also reduces Andosol OC (6.5 to 0.8%), total N (4.51 to 0.95‰) and CEC (22.0 to 10.2 cmol.kg–1), but increases soil pH (4.62 to 6.54), the sum of exchangeable cations (3.58 to 5.74 cmol.kg–1) and the abundance of soil macroaggregates (WSA: 38.2 to 57.0%). In comparison with tillage, fallow increases Andosol OC (4.8 to 6.5%), total N (2.95 to 5.04‰), CEC (18.0 to 21.6 cmol.kg–1), the sum of exchangeable cations (3.58 to 5.05 cmol.kg–1) and the abundance of soil macroaggregates (WSA: 12.0 to 48.8%). Globally, the tillage management deteriorates Andosol chemical and physical properties affecting fertility, whereas the fallow management restores them. The burning management also improves some Andosol chemical and physical properties affecting quality, but it won’t last long.展开更多
The catalytic activity of carbon nanotubes-supported vanadium oxide(V_2O_5/CNTs) catalysts in the selective catalytic reduction(SCR) of NO with NH_3 at low temperatures(<250℃) was investigated.The effects of V_2O_...The catalytic activity of carbon nanotubes-supported vanadium oxide(V_2O_5/CNTs) catalysts in the selective catalytic reduction(SCR) of NO with NH_3 at low temperatures(<250℃) was investigated.The effects of V_2O_5loading,reaction temperature,and presence of SO_2 on the SCR activity were evaluated.The results show that V_2O_5/CNTs catalysts exhibit high activity for NO reduction with NH_3 at low-temperatures.The catalysts also show very high stability in the presence of SO_2.More interestingly,their activities are significantly promoted instead of being poisoned by SO_2.The promoting effect of SO_2 is distinctly associated with V_2O_5 loading,particularly maximized at low V_2O_5 loading,which indicated the role of CNTs support in this effect.The promoting effect of SO_2 at low temperatures suggests that V_2O_5/CNTs catalysts are promising catalytic materials for low-temperature SCR reactions.展开更多
Tea (Camellia sinensis (L) O. Kuntze) is a perennial crop grown for beverage consumption. Its production is the leading foreign exchange earner in Kenya contributing about 26% foreign exchange and 4% GDP. Nitrogen (N)...Tea (Camellia sinensis (L) O. Kuntze) is a perennial crop grown for beverage consumption. Its production is the leading foreign exchange earner in Kenya contributing about 26% foreign exchange and 4% GDP. Nitrogen (N), Phosphorus (P) and potassium (K) are the recommended nutrients for tea production. However, their continuous use has been reported to have negative effect on soil physico-chemical properties and health. Sheep manure has been recommended in tea production for its soil pH buffering effect and increased tea yields. However, effects of sheep manure enriched with inorganic fertilizer on tea soils and yield have not been conclusively investigated. This study was established at KALRO—Tea Research Institute Kericho in Timbilil estate to determine the impact of seasonal variation on soil pysico-chemical properties and yields on enriched sheep manure used. Randomized complete block design (RCBD) experimental design was adopted with 14 treatments replicated thrice. The treatments were: control with no fertilizer use, NPK at 180 Kgs N/ha/yr, sheep manure only and two enriched sheep manure ratios of 4:1 and 8:1 which translates to a mixture of (4:1) 4 parts of sheep manure and 1 part of D.A.P inorganic fertilizer. Same applied to 8:1 ratio, respectively at rates of 60, 120, 180 and 240 Kgs N/ha once per year. Data were subjected to ANOVA in GenStat statistical package and means separated by Duncan’s multiple range tests at P ≤ 0.05 significance level. Results obtained showed that soil physico-chemical properties and tea yields were influenced significantly (P ≤ 0.05) by treatments applied. Soil available water and organic matter were higher on enriched sheep manure 4:1 at 240 rate used while soil porosity and bulk density were not significantly affected. Total N and P, increased with enriched sheep manure ratio of 4:1 at 240 rate while K+, Ca2+, Mg2+, Mn and pH increased with sole application of sheep manure at rate 180 and enriched sheep manure 8:1 at 180 rate. Tea yields increased with enriched sheep manure 4:1 ratios at the rates of 240. The findings recommend enriched sheep manure 4:1 ratio at 240 rates to be adopted by tea farmers within Kericho region. Further studies involving different geographical locations are proposed.展开更多
Water quality in North Alabama is becoming a critical issue and in order to understand the quality of water in the Flint Creek and Flint Rivers,concentration levels of physicochemical parameters and trace heavy metals...Water quality in North Alabama is becoming a critical issue and in order to understand the quality of water in the Flint Creek and Flint Rivers,concentration levels of physicochemical parameters and trace heavy metals were measured in six strategically selected sites within the streams to obtain baseline data.A total of 192 surface water samples were collected and analyzed for total phosphorous and five heavy metals of concern.Physical and chemical parameters were determined for dissolved oxygen(DO),turbidity,pH,temperature,water conductivity and total phos-phorous.The concentration of the DO was above guidelines in three sites at both rivers.All metals were statistically significant(P≤0.05)at 95%confidence interval by watershed.Aluminum and lead exceeded their maximum permissible levels.The results for heavy metals in this study show location and seasonal variability.There was significantly higher heavy metal content during winter>spring>summer>fall.The values for the Hazard Quotient and Hazard Index for both watershed sites were mostly more than 1,indicating some levels of concern.Additionally,surrounding rocks and other anthropogenic sources appeared to be causing the elevated chemical content of the rivers and may have resulted in significant adverse impacts on the study areas.展开更多
文摘Most drinkable water supplied to the public in Mexico City comes from deep wells which extract water from the subsoil. Before being distributed, it is treated in steel filtration tanks. This water must be subject to evaluation through physic-chemical and bacteriological analyses in order to determine its quality. However, doubts always remain over the influence of the components of this water on the corrosive behavior of the filtration tanks. In light of this, this article studies the physic-chemical characterization values of water and presents the results. This has also enabled the analysis of the corrosion speed of filtration tanks components, boilers and water-cooled systems, where incrustations in pipes, obstructions and loss of heat transfer efficiency occur, rendering drinkable water bad tasting and, after some time, causing pitting corrosion although this type of corrosion only causes serious problems in the long term.
基金supported by Project in the National Science & Technology Pillar Program (2600BAD26B02-1)
文摘Soil plays an important role in desert ecosystem, and is vital in constructing a steady desert ecosystem. The management and restoration of desertified land have been the focus of much discussion. The soil in Shapotou desert region has developed remarkably since artificial sand-binding vegetation established in 1946. The longer the period of dune stabilization, the greater the thickness of microbiotic crusts and subsoil. Meanwhile, proportion of silt and clay increased significantly, and soil bulk density declinced. The content of soil organic matter, N, P, and K similarly increased. Therefore, soil has developed from aeolian sand soil to Calcic-Orthic aridisols. This paper discusses the effects brought about by dust, microbiotic soil crust and soil microbes on soil-forming process. Then, we analyzed the relation between soil formation and sand-binding vegetation evolution, in order to provide a baseline for both research on desert ecosystem recovery and ecological environment governance in arid and semi-arid areas.
文摘To assess the impact of land use on the Andosol fertility, changes in chemical and physical properties affecting soil quality were monitored on Andosols from Mount Bambouto submitted to four different land use and management systems: natural cover, tillage, burning and fallow. In comparison with the natural cover, tillage reduces Andosol OC (6.5 to 4.8%), total N (4.51 to 2.95‰), CEC (22.0 to 20.9 cmol.kg–1) and the abundance of soil macro-aggregates expressed by the water stable aggregates (WSA) varies from 53.8 to 12.0%;and increases the bulk density (0.69 to 1.09 g.cm–3) and the sum of exchangeable cations (3.58 to 4.84 cmol.kg–1). Burning also reduces Andosol OC (6.5 to 0.8%), total N (4.51 to 0.95‰) and CEC (22.0 to 10.2 cmol.kg–1), but increases soil pH (4.62 to 6.54), the sum of exchangeable cations (3.58 to 5.74 cmol.kg–1) and the abundance of soil macroaggregates (WSA: 38.2 to 57.0%). In comparison with tillage, fallow increases Andosol OC (4.8 to 6.5%), total N (2.95 to 5.04‰), CEC (18.0 to 21.6 cmol.kg–1), the sum of exchangeable cations (3.58 to 5.05 cmol.kg–1) and the abundance of soil macroaggregates (WSA: 12.0 to 48.8%). Globally, the tillage management deteriorates Andosol chemical and physical properties affecting fertility, whereas the fallow management restores them. The burning management also improves some Andosol chemical and physical properties affecting quality, but it won’t last long.
基金Supported by the National Natural Science Foundation of China(21006065)the Zhejiang Provincial Natural Science Foundation of China(Y5100009)
文摘The catalytic activity of carbon nanotubes-supported vanadium oxide(V_2O_5/CNTs) catalysts in the selective catalytic reduction(SCR) of NO with NH_3 at low temperatures(<250℃) was investigated.The effects of V_2O_5loading,reaction temperature,and presence of SO_2 on the SCR activity were evaluated.The results show that V_2O_5/CNTs catalysts exhibit high activity for NO reduction with NH_3 at low-temperatures.The catalysts also show very high stability in the presence of SO_2.More interestingly,their activities are significantly promoted instead of being poisoned by SO_2.The promoting effect of SO_2 is distinctly associated with V_2O_5 loading,particularly maximized at low V_2O_5 loading,which indicated the role of CNTs support in this effect.The promoting effect of SO_2 at low temperatures suggests that V_2O_5/CNTs catalysts are promising catalytic materials for low-temperature SCR reactions.
文摘Tea (Camellia sinensis (L) O. Kuntze) is a perennial crop grown for beverage consumption. Its production is the leading foreign exchange earner in Kenya contributing about 26% foreign exchange and 4% GDP. Nitrogen (N), Phosphorus (P) and potassium (K) are the recommended nutrients for tea production. However, their continuous use has been reported to have negative effect on soil physico-chemical properties and health. Sheep manure has been recommended in tea production for its soil pH buffering effect and increased tea yields. However, effects of sheep manure enriched with inorganic fertilizer on tea soils and yield have not been conclusively investigated. This study was established at KALRO—Tea Research Institute Kericho in Timbilil estate to determine the impact of seasonal variation on soil pysico-chemical properties and yields on enriched sheep manure used. Randomized complete block design (RCBD) experimental design was adopted with 14 treatments replicated thrice. The treatments were: control with no fertilizer use, NPK at 180 Kgs N/ha/yr, sheep manure only and two enriched sheep manure ratios of 4:1 and 8:1 which translates to a mixture of (4:1) 4 parts of sheep manure and 1 part of D.A.P inorganic fertilizer. Same applied to 8:1 ratio, respectively at rates of 60, 120, 180 and 240 Kgs N/ha once per year. Data were subjected to ANOVA in GenStat statistical package and means separated by Duncan’s multiple range tests at P ≤ 0.05 significance level. Results obtained showed that soil physico-chemical properties and tea yields were influenced significantly (P ≤ 0.05) by treatments applied. Soil available water and organic matter were higher on enriched sheep manure 4:1 at 240 rate used while soil porosity and bulk density were not significantly affected. Total N and P, increased with enriched sheep manure ratio of 4:1 at 240 rate while K+, Ca2+, Mg2+, Mn and pH increased with sole application of sheep manure at rate 180 and enriched sheep manure 8:1 at 180 rate. Tea yields increased with enriched sheep manure 4:1 ratios at the rates of 240. The findings recommend enriched sheep manure 4:1 ratio at 240 rates to be adopted by tea farmers within Kericho region. Further studies involving different geographical locations are proposed.
文摘Water quality in North Alabama is becoming a critical issue and in order to understand the quality of water in the Flint Creek and Flint Rivers,concentration levels of physicochemical parameters and trace heavy metals were measured in six strategically selected sites within the streams to obtain baseline data.A total of 192 surface water samples were collected and analyzed for total phosphorous and five heavy metals of concern.Physical and chemical parameters were determined for dissolved oxygen(DO),turbidity,pH,temperature,water conductivity and total phos-phorous.The concentration of the DO was above guidelines in three sites at both rivers.All metals were statistically significant(P≤0.05)at 95%confidence interval by watershed.Aluminum and lead exceeded their maximum permissible levels.The results for heavy metals in this study show location and seasonal variability.There was significantly higher heavy metal content during winter>spring>summer>fall.The values for the Hazard Quotient and Hazard Index for both watershed sites were mostly more than 1,indicating some levels of concern.Additionally,surrounding rocks and other anthropogenic sources appeared to be causing the elevated chemical content of the rivers and may have resulted in significant adverse impacts on the study areas.
