Anoxification recovery using underwater LED irradiation and influence of its optical spectrum on water quality improvement     

Honglikith  Daoluang  Harada  Masayoshi  Hiramatsu  Kazuaki  Tabata  Toshinori  Ozaki  Akinori 《Paddy and Water Environment》2022,20(1):153-175

Paddy and Water Environment - This study focuses on a method for improving water quality via anoxification recovery using underwater LED treatment in an organically polluted reservoir. The main aim...  相似文献   

Impact of aquatic plants on entrainment phenomena based on wind-induced flow in a closed density stratified water area     

Akinori?OzakiEmail author  Ken?Mori  Eiji?Inoue  Tomokazu?Haraguchi 《Paddy and Water Environment》2004,2(3):125-134

It has recently been proposed that water purification could be performed using aquatic plants, since they absorb nutrient salts. The behavior of a substance in a closed water area is affected by turbulent flows from wind-induced flow, which is a mechanical disturbance, and convective flow, which is a thermal disturbance. In a closed density stratified water area, wind-induced flow gives rise to the entrainment phenomenon at the density interface. This phenomenon, which is based on mixing between the upper and lower water layers, lowers the density interface and so affects the water quality. We experimentally investigated the effect of aquatic plants on the turbulent flow from a mechanical disturbance in the closed water area. Results indicated that the presence of floating and submerged plants had a significant effect on the scale of the turbulent entrainment, and that the entrainment velocity depended on the overall Richardson number to the power of –3/2.  相似文献   

Lime-nitrogen application affects nitrification, denitrification, and N2O emission in an acidic tea soil     

Akinori Yamamoto  Hiroko Akiyama  Takuji Naokawa  Yasuhiro Miyazaki  Yusuke Honda  Yukimasa Sano  Yasuhiro Nakajima  Kazuyuki Yagi 《Biology and Fertility of Soils》2014,50(1):53-62

Lime-N (calcium cyanamide, CaCN₂) acts as both fertilizer and pesticide. Lime-N may reduce nitrous oxide (N₂O) emission from soil, although its effectiveness and the relative mechanisms are not well understood. The aim of the study was to quantify the effect of lime-N on N₂O emission from the acidic soil of tea fields. The study design consisted of two treatments: conventional fertilizer (CF) (application of conventional organo-chemical fertilizer) and lime-N (LN) (application of approximately 53 % of the applied N as lime-N and the remaining as conventional organo-chemical fertilizer). Both treatments had the same amount of N, P₂O₅, and K₂O applied to soil between plant canopies; fertilizer was incorporated into soil. We measured N₂O emissions and environmental and microbial parameters of soil between plant canopies and under the canopy of tea plants, including the concentrations of dicyandiamide and cyanamide derived from lime-N. Nitrous oxide emission from soil between plant canopies was lower in the LN treatment than in the CF treatment, and soil ammonium oxidation activity and soil denitrification rate decreased after lime-N application. We applied the acetylene inhibition technique and analyzed isotopomer ratios of N₂O; the results of both techniques suggested that denitrification was the major process of N₂O production in the soil between plant canopies, despite relatively low water-filled pore space. Cumulative N₂O emission over the 366 days of the experiment was 36.0 % lower in the LN treatment than in the CF treatment (P?<?0.05). Our results suggest that lime-N application decreases N₂O emission by inhibiting both nitrification and denitrification processes in the acidic soil.  相似文献