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161.
162.
163.
Effect of nitrification inhibitor DMPP on nitrogen leaching, nitrifying
organisms, and enzyme activities in a rice-oilseed rape cropping system 总被引:9,自引:0,他引:9
LI Hu LIANG Xinqiang CHEN Yingxu LIAN Yanfeng TIAN Guangming NI Wuzhong 《环境科学学报(英文版)》2008,20(2):149-155
DMPP (3,4-dimethylpyrazole phosphate) has been used to reduce nitrogen (N) loss from leaching or denitrification and to improve N supply in agricultural land. However, its impact on soil nitrifying organisms and enzyme activities involved in N cycling is largely unknown. Therefore, an on-farm experiment, for two years, has been conducted, to elucidate the effects of DMPP on mineral N (NH4^+- N and NO3^--N) leaching, nitrifying organisms, and denitrifying enzymes in a rice-oilseed rape cropping system. Three treatments including urea alone (UA), urea + 1% DMPP (DP), and no fertilizer (CK), have been carded out. The results showed that DP enhanced the mean NH4^+-N concentrations by 19.1%-24.3%, but reduced the mean NO3^--N concentrations by 44.9%-56.6% in the leachate, under a two-year rice-rape rotation, compared to the UA treatment. The population of ammonia oxidizing bacteria, the activity of nitrate reductase, and nitrite reductase in the DP treatment decreased about 24.5%-30.9%, 14.9%-43.5%, and 14.7%-31.6%, respectively, as compared to the UA treatment. However, nitrite oxidizing bacteria and hydroxylamine reductase remained almost unaffected by DMPP. It is proposed that DMPP has the potential to either reduce NO3^--N leaching by inhibiting ammonia oxidization or N losses from denitrification, which is in favor of the N conversations in the rice-oilseed rape cropping system. 相似文献
164.
Effect of inorganic carbon on anaerobic ammonium oxidation enriched in
sequencing batch reactor 总被引:1,自引:0,他引:1
The present lab-scale research reveals the enrichment of anaerobic ammonium oxidation microorganism from methanogenic anaerobic granular sludge and the effect of inorganic carbon(sodium bicarbonate)on anaerobic ammonium oxidation.The enrichment of anammox bacteria was carried out in a 7.0-L sequencing batch reactor(SBR)and the effect of bicarbonate on anammox was conducted in a 3.0-L SBR.Research results,especially the biomass,showed first signs of anammox activity after 54 d cultivation with synthetic w... 相似文献
165.
珠江口水体、沉积物及水生动物中HCHs和DDTs的含量与生态风险评价 总被引:8,自引:1,他引:7
利用气相色谱(GC-ECD)方法对珠江口水、沉积物及水生动物体内六六六(HCHs)和滴滴涕(DDTs)的污染现状进行了调查,并对该类污染物在水体多介质中的转移分配规律及对水生态环境安全的影响作了初步研究.结果表明,珠江口表层水中HCHs总量检出范围为1.12~8·91ng·L-1,平均值为4.25ng·L-1;;DDTs总量检出范围为2.61~16.86ng·L-1,平均值为7.66ng·L-1.表层沉积物(以干重计)中HCHs总量检出范围2.51~4.75ng·g-1,平均值为3.61ng·g-1;;DDTs总量检出范围为3.01~6.24ng·g-1平均值为4.33ng·g-1.水生动物中河蚬体内的HCHs和DDTs含量最高,分别为44.49和122.62ng·g-1;;虾类次之,为41.04和82.27ng·g-1;;鱼类最低,平均值分别为27.95和65.43ng·g-1.同国内外其他地区河流比较,珠江口水体和底泥中的HCHs和DDTs污染程度较低,但仍具有一定的潜在生态风险.林丹、三氯杀螨醇取代工业生产HCHs、DDTs,成为该水域有机氯污染的重要来源. 相似文献
166.
表面活性剂对二嗪磷在不同土壤中吸附迁移的影响 总被引:3,自引:0,他引:3
采用批量平衡法和薄层层析法, 分别研究了不同浓度的3种表面活性剂十二烷基苯磺酸钠(SDBS)、Tween80和十六烷基三甲基溴化胺(CTAB) 对二嗪磷在湖南省具有代表性的6大土类、9种不同母质土壤中吸附和迁移性能的影响. 结果表明, SDBS能够明显地降低各种土壤对二嗪磷的吸附, 促进二嗪磷的迁移作用, 并且吸附平衡系数(Kd)、比移值(Rf)分别随SDBS浓度增大而增大、减小.浓度成显著的负相关和正相关关系.Tween-80和CTAB对二嗪磷在土壤中的吸附和迁移表现出一定的相似性, Tween-80浓度在0.1~2倍临界胶束浓度(CMC)范围内(CTAB浓度为0.80~87.43 mg·L-1), 其Kd值、Rf值分别随表面活性剂浓度增大而增大、减小, 而Tween-80浓度在2~5倍临界胶束浓度的范围内(CTAB浓度为87.43~191.60 mg·L-1.), 则出现与之相反的变化趋势. 相似文献
167.
堆肥嗜热纤维素分解菌的筛选鉴定及其强化堆肥研究 总被引:6,自引:0,他引:6
对采集于农业堆肥高温期的微生物样品进行30d的高温驯化,驯化完成后从中筛选得到15株嗜热纤维素分解菌,经形态学特征、生理生化反应及16S rDNA序列同源性比对鉴定为:Bacillus sp3株,Paenibacillus sp1株,Bacillus licheniformis3株,Bacillus subtilis4株,Brevibacillus borstelensis1株,Bacillus coagulans3株.将筛选得到的菌种添加至高纤维素含量的堆体进行效果验证,结果表明添加嗜热纤维素分解菌对堆肥pH变化无显著影响,但可提高堆肥高温期温度、延长高温期并显著地降低堆肥产品的C/N和有机质含量,显著降低纤维素和半纤维素含量,加快堆肥腐熟.堆体有机质降解动力学结果表明,堆体接菌和不接菌处理的有机质最大降解度分别为62.5481%和61.7101%,速率常数分别为0.1250d-1和0.1051d-1,接菌处理的堆肥比对照堆肥提前6d达到稳定.研究表明,添加筛选的嗜热纤维素分解菌能缩短堆肥周期. 相似文献
168.
在常温(25℃)条件下,对Fenton与序批式活性污泥法(SBR)组合工艺处理博落回提取废水的特性进行了研究.结果表明,当进水CODCr为7300mg·L-1时,通过多个单因素试验确定的最佳Fenton反应条件为:初始pH=3.0,n(H2O2)∶n(Fe2+)=15,H2O2投加量为7300mg·L-1.在此条件下反应120min后,CODCr去除率为65.3%,BOD5/CODCr由原水的0.14上升到出水的0.22,可生化性得到提高.同时,研究证明,出水pH不影响CODCr去除率,但污泥体积指数(SVI)值随着出水pH的增大而减小.Fenton氧化出水经SBR工艺处理后,CODCr可控制在500mg·L-1以内,达到国家三级排放标准. 相似文献
169.
Junguo He Guangming Zhang Haifeng Lu 《Frontiers of Environmental Science & Engineering in China》2010,4(3):334-339
The conventional treatment method of soybean wastewater is expensive and generates waste sludge that requires further handling.
Purple nonsulfur bacteria (PNSB) wastewater treatment is a clean technology and can generate single cell protein while degrading
pollutants. Awild strain of PNSB, Rhodobacter sphaeroides Z08, was isolated from local soil and was used to treat soybean wastewater. To develop a cost-effective process, the work
was performed under natural conditions without artificial light, aeration, nutrients addition, or pH and temperature adjustment.
The results showed that the wild strain Rhodobacter sphaeroides Z08 could grow well under natural conditions. The growth curve showed two quick-growth periods and a turning point. The Z08
treatment of soybean wastewater was zero order reaction and COD reduction was 96% after 10 d. The major byproducts of the
process were C2–C5 organic acids, predominantly butyric acid. No alcohol was found in the effluent. The initial COD/bacterial-mass
ratio (F/M) had a significant effect on soybean wastewater treatment efficiency. When the initial F/M was lower than 10 mg-COD/mg-bacteria,
a sufficient amount of time to achieve 90% of COD reduction was only three days. The Z08 biomass yield was 0.28 g·g−1, and the bacterial protein content was 52%. 相似文献
170.
以长沙市某污水处理厂二沉池为例,采用多相流混合物模型与k-ε湍流模型结合对辐流式二沉池内速度场和污泥浓度场进行了数值模拟.以出水口悬浮物浓度(SS)为响应目标,对影响二沉池沉淀效果的3个影响因素(进水口流速、颗粒污泥粒径、挡板的淹没深度)进行中心复合设计(central composite design,CCD),并经响应表面法分析得到影响出水SS的二次回归模型,确定了二沉池沉降的最佳条件:进水口流速为0.03m·s-1,颗粒污泥粒径为220.41μm,挡板的淹没深度为3.45m,采用数值仿真模拟实验得到出水口悬浮物浓度值为2.4mg·L-1,较优化之前的仿真结果一周平均值6.7mg·L-1相比,其处理效率提高了64.2%.采用数值仿真和响应表面法结合对二沉池工艺条件进行优化研究,可以加速寻优过程,是工艺优化的辅助工具. 相似文献