Phosphorus (P) is a primary limiting nutrient in rivers and streams, and excessive P results in eutrophication of freshwater systems, in turn, excessive algal growth/toxic algal blooms, oxygen depletion, and water qua...Phosphorus (P) is a primary limiting nutrient in rivers and streams, and excessive P results in eutrophication of freshwater systems, in turn, excessive algal growth/toxic algal blooms, oxygen depletion, and water quality degradation. This study analyzed P pool, and hydrolysis of organic P (OP) by native phosphatases (NPase) in the water samples collected in the Bronx River. The soluble reactive P (SRP) of most of the sites’ water collected in 2006 and 2007 were higher (average 67 μg?L–1 and 68 μg?L–1, respectively) than the US Environmental Protection Agency’s (EPA) standard of 15 μg?L–1. The SRP% (SRP/TP%) average was 27% in 2006, much lower than in 2007 of SRP% average 83%. The OP% (OP/TP%) average was 73% in 2006, which was much higher than the OP% in 2007 (which was only 17%). The SRP concentrations and distributions (%), and the total P (TP) concentrations were in substantial amounts compared with other rivers. The NPase hydrolyzed OP % was up to 100% in 2006 and 2007 water samples. The average of NPase% was 59% in 2006 and 73% in 2007. The NPase average concentrations were 348 μg?L–1 in 2006, and 175 μg?L–1 in 2007. The NPase hydrolyzed up to 100% of OP% in the Bronx River water samples at 37?C, indicating a potential threat of eutrophication of freshwater systems as the global rise in temperature may continue to occur.展开更多
The study was conducted to investigate the N2O emissions and dissolved N2O in the leachate during the nonflooding period in nongrowing paddy fields.Three kinds of paddy soils were repacked to soil columns and were sup...The study was conducted to investigate the N2O emissions and dissolved N2O in the leachate during the nonflooding period in nongrowing paddy fields.Three kinds of paddy soils were repacked to soil columns and were supersaturated with water initially and dried gradually in a greenhouse to attain the N2O emissions flux during the incubation.Soils with the texture of silty clay-loam (Q and H) produced cracks during the drying of soil,but soil with the texture of silty loam (X) did not form the cracks.Cracked s...展开更多
文摘Phosphorus (P) is a primary limiting nutrient in rivers and streams, and excessive P results in eutrophication of freshwater systems, in turn, excessive algal growth/toxic algal blooms, oxygen depletion, and water quality degradation. This study analyzed P pool, and hydrolysis of organic P (OP) by native phosphatases (NPase) in the water samples collected in the Bronx River. The soluble reactive P (SRP) of most of the sites’ water collected in 2006 and 2007 were higher (average 67 μg?L–1 and 68 μg?L–1, respectively) than the US Environmental Protection Agency’s (EPA) standard of 15 μg?L–1. The SRP% (SRP/TP%) average was 27% in 2006, much lower than in 2007 of SRP% average 83%. The OP% (OP/TP%) average was 73% in 2006, which was much higher than the OP% in 2007 (which was only 17%). The SRP concentrations and distributions (%), and the total P (TP) concentrations were in substantial amounts compared with other rivers. The NPase hydrolyzed OP % was up to 100% in 2006 and 2007 water samples. The average of NPase% was 59% in 2006 and 73% in 2007. The NPase average concentrations were 348 μg?L–1 in 2006, and 175 μg?L–1 in 2007. The NPase hydrolyzed up to 100% of OP% in the Bronx River water samples at 37?C, indicating a potential threat of eutrophication of freshwater systems as the global rise in temperature may continue to occur.
基金the National Basic Research Program (973) of China (No.2002CB410807).
文摘The study was conducted to investigate the N2O emissions and dissolved N2O in the leachate during the nonflooding period in nongrowing paddy fields.Three kinds of paddy soils were repacked to soil columns and were supersaturated with water initially and dried gradually in a greenhouse to attain the N2O emissions flux during the incubation.Soils with the texture of silty clay-loam (Q and H) produced cracks during the drying of soil,but soil with the texture of silty loam (X) did not form the cracks.Cracked s...
