[Photo-induced Phosphate Release from Organic Phosphorus Decomposition Driven by Fe(â ¢)-oxalate Complex in Lake Water].

The phosphate released from organic phosphorus photo-decomposition has a significantly influence on the phosphorus levels in the water column in lakes. In order to reveal the effect of organic phosphorus photo-decomposition on phosphate level in lake water, the phosphate released from organic phosphorus photo-decomposition driven by Fe(Ⅲ)-oxalate complex under UV-Vis and sunlight irradiation was investigated in natural lake water using glyphosate as the model organic phosphorus. The effects of pH and initial concentration of Fe(Ⅲ), oxalate and glyphosate on the phosphate released from glyphosate photolysis were studied. The results showed that phosphate could be released from glyphosate degradation by Fe(Ⅲ)-oxalate complex under UV-Vis and sunlight irradiation. The concentration of phosphate reached 0.25 mg·L-1 and 0.18 mg·L-1 under UV-Vis and sunlight irradiation for 60 and 720 min, respectively. The amount of phosphate released increased with the increase of the initial concentration of Fe(Ⅲ), as well as the increasing oxalate and glyphosate concentration in lake water. However, the increase of pH could significantly inhibit this process in the reaction system. The concentration of phosphorus decreased with the addition of isopropanol, which indicated that the hydroxyl radical (·OH) was one of the main active oxygen species of Fe(Ⅲ)-oxalate complex. The rates of·OH production for Fe(Ⅲ)-oxalate/UV-Vis and Fe(Ⅲ)-oxalate/sunlight systems were 0.52×10-2 µmol·(L·min)-1 and 0.03×10-2 µmol·(L·min)-1, respectively. The steady-state concentrations of hydroxyl radical (·OH) for the Fe(Ⅲ)-oxalate/UV-Vis conditions were 4.74×10-16 mol·L-1 and 0.27×10-16 mol·L-1 for the Fe(Ⅲ)-oxalate/sunlight system.

[Pollution Characteristics of Surface Runoff of Typical Town in Chongqing City].

Six kinds of impermeable underlying surface, cement tile roof, asbestos roof, cement flat roof, residential concrete pavement, asphalt pavement of restaurants, asphalt pavement of oil depot, and a combined sewer overflow canal in the Jiansheng town of Dadukou district in Chongqing city were chosen as sample plots to study the characteristics of nutritional pollutants and heavy metals in town runoff. The research showed that the average mass concentrations of TSS, COD, TN, TP in road runoff were (1681.2 +/- 677.2), (1154.7 +/- 415.5), (12.07 +/- 2.72), (3.32 +/- 1.15) mgL(-1), respectively. These pollutants were higher than those in roof runoff which were (13.3 +/- 6.5), (100.4 +/- 24.8), (3.58 +/- 0.70), (0.10 +/- 0.02) mg x L(-1), respectively. TDN accounted for 62.60% +/- 34.38% of TN, and TDP accounted for 42.22% +/- 33.94% of TP in the runoff of impermeable underlying surface. Compared with the central urban runoff, town runoff in our study had higher mass concentrations of these pollutants. The mass concentrations of TSS, COD, TDN, TN, TDP and TP in the combined sewer overflow were (281.57 +/- 308.38), (231.21 +/- 42.95), (8.16 +/- 2.78), (10.60 +/- 3.94), (0.38 +/- 0.23) and (1.51 +/- 0.75) mg x L(-1), respectively. The average levels of heavy metals in this kind of runoff did not exceed the class VI level of the surface water environmental quality standard. Most pollutants in the combined sewer overflow had first flush. However, this phenomenon was very rare for TSS. There was a significant positive correlation between TSS and COD, TP in the combined sewer overflow. And this correlation was significant between NH4+ -N and TP, TDP, TN, TDP. However, a negative correlation existed between NO3- -N and all other indicators.

[Response of phosphorus components in sediments from eutrophic lake to external sulfate].

A six week experiment under indoor simulated condition was carried out to investigate the external sulfate transformation between the sediments and overlying water from Lake Nanhu in Wuhan, China, and the influence of sulfate on the phosphorus components was also studied. The results showed that the sulfate input increased the pH and lowered the Eh in the overlying water. The sulfate concentration in the overlying water decreased with time, and it was assumed that there existed an obvious transformation of sulfate to other forms of sulfur compounds according to the variation of sulfate concentration in the pore water. The sulfate reduction index increased with higher input content of sulfate. The amount of sulfate reducing bacteria (SRB) in the sediments achieved the peak value in the second week, and the SRB amounts of S500 and S1000 were much higher than that of the control. 31P-NMR was used to characterize the relative quantity of phosphorus compounds in the sediment extracts leached by NaOH-EDTA. The components of phosphorus in Nanhu Lake sediment were mainly orthophosphate, phosphate monoester, phosphodiester and pyrophosphate. The predominant one was orthophosphate (84.10%-95.54% of total phosphorus). The contents of other phosphorus components were followed: phosphate monoester > phosphodiester > pyrophosphate, and they increased due to the input of sulfate during the first four weeks, and decreased in the last two weeks. The external sulfate accelerated the release of orthophosphate from sediments to overlying water in a whole, and increased the contents of phosphate monoester, phosphodiester and pyrophosphate in sediments when the amounts of sulfate reducing bacteria were high.

[Effect of Fe-Mn-Si on the biomass structure of Eichhornia crassipes].

Eichhornia crassipes (water hyacinth) was cultivated under different iron (Fe), manganese (Mn) and silicon (Si) nutrient treatments for its biomass characteristics research which was determined by various items including nutrient element content (Fe, Mn and Si), adsorption sites and active function groups. The results show that Mn and Si can enhance acidic sites of the plant, in which Mn plays a great role, but Fe reduces the acidic sites. The sequence of acidic sites' amount among three parts of the plant is root > stem > leaf, in the treatment of Fe, Mn and their combination, and leaf > stem > root in Si treatment. The amount of alkaline sites is less than that of acidic sites, and the difference in their distributions among three parts of the plant is not great. Mn and Si treated Eichhornia crassipes stalks have more amorphous material, such as lignin, pectin and xylan (hemicellulose), which have more functional groups of -OH, -COOH and acidic sites.

[Coupling effects of temperature, moisture, and nitrogen application on greenhouse soil pH and EC].

A laboratory incubation experiment was conducted to study the effects of temperature (T), moisture (W), nitrogen application (N), and their combinations on the pH and EC of greenhouse soil having cultivated for 5 years. The results showed that with the increase of incubation time, soil pH was decreasing, which could be well described by the first-order kinetic model, and the pH decreasing rate (k) under effects of test factors was in the order of N > W > W x N > T x W. Soil EC increased quickly to the maxima in the first week of incubation, decreased slightly then, and finally reached to a constant (EC(sty)). The EC(sty) value was significantly affected by N, W, T x W, T, and W x N. Reducing nitrogen application and rational deficit irrigation could effectively postpone the soil acidification and EC increase. A regression equation of k and EC(sty) was established, which could be used to predict the changes of soil pH and EC under different conditions of moisture regime and nitrogen application.