Recovery of gold and silver from a sulphide concentrate by thiourea leaching was investigat-ed.The effects of various parameters on the process,such as oxidants,the initial concentrationof thiourea and acidity in solu...Recovery of gold and silver from a sulphide concentrate by thiourea leaching was investigat-ed.The effects of various parameters on the process,such as oxidants,the initial concentrationof thiourea and acidity in solutions as well as reaction temperature,were systematically exam-ined.From the results it was confirmed that(a)oxidants had no significant influence on the dis-solution of gold and silver at a fixed initial concentration of thiourea;(b)the initial concentra-tion of thiourea and acidity affected the dissolution rate only in the earliest period of leaching;(c)the rate of the process was controlled by reagent diffusion.The optimum operations wereworked out for the thiourea leaching process of the concentrate.展开更多
研究了纳米银对南美白对虾苗的毒性、弧菌的杀灭能力和抑制效果,以及可能导致养殖水体和养殖对虾中的银累积。结果表明,纳米银对南美白对虾苗的96 h半致死浓度(LC50)为推荐使用浓度(0.5 mL/m^(3))的2241.54倍(1120.77 mL/m^(3)),48 h LC...研究了纳米银对南美白对虾苗的毒性、弧菌的杀灭能力和抑制效果,以及可能导致养殖水体和养殖对虾中的银累积。结果表明,纳米银对南美白对虾苗的96 h半致死浓度(LC50)为推荐使用浓度(0.5 mL/m^(3))的2241.54倍(1120.77 mL/m^(3)),48 h LC50-为推荐使用浓度的5421.70倍(2780.15 mL/m^(3))。相应的安全浓度(SC)(按0.05的应用系数)分别为96 h SC 56.04 mL/m^(3)和48 h SC 135.54 mL/m^(3)。指出,纳米银能够明显杀灭和抑制养殖水体和对虾身体的弧菌,是一种高效的疾病预防药物,但会造成养殖水体银浓度增加,并在对虾体内有一定量的累积。展开更多
Dam discharges over spillways are the main reason for the gas-supersaturated water generated in rivers.Local aquatic organisms,especially fish,readily develop gas bubble disease(GBD) in a river with total dissolved ga...Dam discharges over spillways are the main reason for the gas-supersaturated water generated in rivers.Local aquatic organisms,especially fish,readily develop gas bubble disease(GBD) in a river with total dissolved gas supersaturation(TDGS).Sometimes,fish will die after a specific exposure period,which negatively affects the biological equilibrium.In this study,the influence of TDGS on silver carp was explored.Silver carp were exposed to gas-supersaturated water with TDGS levels of 140%,135%,130%,125%,120%,and 110%to test the impact of TDGS.Some silver carp died when the TDGS level was 120%or higher,and all the silver carp exposed to a TDGS level of 140%died within10 h.In comparison with the Chinese sucker,Prenant's schizothoracin,and rock carp,silver carp seem less sensitive to TDGS.In addition,we tested the catalase(CAT) activity in the muscles and gills of silver carp after they were exposed to gas-supersaturated water with a TDGS level of140%.The CAT activity changed with time;it increased first and then decreased until it was lower than the initial CAT activity.The results of this study can provide basic data for developing a standard for environmental evaluation.展开更多
文摘Recovery of gold and silver from a sulphide concentrate by thiourea leaching was investigat-ed.The effects of various parameters on the process,such as oxidants,the initial concentrationof thiourea and acidity in solutions as well as reaction temperature,were systematically exam-ined.From the results it was confirmed that(a)oxidants had no significant influence on the dis-solution of gold and silver at a fixed initial concentration of thiourea;(b)the initial concentra-tion of thiourea and acidity affected the dissolution rate only in the earliest period of leaching;(c)the rate of the process was controlled by reagent diffusion.The optimum operations wereworked out for the thiourea leaching process of the concentrate.
文摘研究了纳米银对南美白对虾苗的毒性、弧菌的杀灭能力和抑制效果,以及可能导致养殖水体和养殖对虾中的银累积。结果表明,纳米银对南美白对虾苗的96 h半致死浓度(LC50)为推荐使用浓度(0.5 mL/m^(3))的2241.54倍(1120.77 mL/m^(3)),48 h LC50-为推荐使用浓度的5421.70倍(2780.15 mL/m^(3))。相应的安全浓度(SC)(按0.05的应用系数)分别为96 h SC 56.04 mL/m^(3)和48 h SC 135.54 mL/m^(3)。指出,纳米银能够明显杀灭和抑制养殖水体和对虾身体的弧菌,是一种高效的疾病预防药物,但会造成养殖水体银浓度增加,并在对虾体内有一定量的累积。
基金supported by the National Natural Science Foundation of China(Grant No.51379136)
文摘Dam discharges over spillways are the main reason for the gas-supersaturated water generated in rivers.Local aquatic organisms,especially fish,readily develop gas bubble disease(GBD) in a river with total dissolved gas supersaturation(TDGS).Sometimes,fish will die after a specific exposure period,which negatively affects the biological equilibrium.In this study,the influence of TDGS on silver carp was explored.Silver carp were exposed to gas-supersaturated water with TDGS levels of 140%,135%,130%,125%,120%,and 110%to test the impact of TDGS.Some silver carp died when the TDGS level was 120%or higher,and all the silver carp exposed to a TDGS level of 140%died within10 h.In comparison with the Chinese sucker,Prenant's schizothoracin,and rock carp,silver carp seem less sensitive to TDGS.In addition,we tested the catalase(CAT) activity in the muscles and gills of silver carp after they were exposed to gas-supersaturated water with a TDGS level of140%.The CAT activity changed with time;it increased first and then decreased until it was lower than the initial CAT activity.The results of this study can provide basic data for developing a standard for environmental evaluation.
