不同类型紫色土土/气界面汞释放通量及其影响因素

运用动力通量箱与RA-915 汞分析仪联用技术,对重庆市3种类型紫色土的土/气界面汞交换通董进行了实地监测.结果显示,不同类型紫色土的土/气界面汞交换通量有一定差异,随着土壤pH值的增加,汞交换通量值增大,酸性紫色土平均通量值为(30.8±23.7)ng·m-2·h-1,中性紫色土为(34.9±25.7)ng·m-2·h-1,石灰性紫色土为(39.0±27.O)ng·m-2·h-1.土/气界面汞交换量受光照、气温、土壤温度和空气相对湿度等因素的影响,汞交换通量与光照、气温和土壤温度呈显著正相关关系,与相对湿度呈显著负相关关系,与大气压不相关.     

有机质含量及其组分对洱海沉积物磷吸附-释放影响

研究了洱海不同湖区沉积物有机质含量、组分及其吸附-释放磷的特征,试图揭示有机质含量及组分对沉积物磷吸附-释放行为的影响机制.结果表明,洱海沉积物磷释放潜能随着沉积物中有机质(TOM)含量的增加而增大,而沉积物磷的最大释放速率(V释,max)和最大释放量(Q释,max)随沉积物中轻组有机质(LFOM)含量的增加而增大,释放平衡时间随活性有机质(ASOM)含量的增加而缩短,磷释放强度随LFOM占TOM比例的增加而减弱.沉积物磷的最大吸附速率(V吸,max)、最大吸附量(Q吸,max)和吸附效率随沉积物TOM含量的增加而增大,吸附平衡时间随TOM含量的增加而缩短,吸附强度随ASOM含量的增加而增强,吸附-解析平衡浓度(EPC0)随ASOM含量的增加而降低.沉积物磷释放后再吸附过程中磷释放的Q释,max和再吸附的V吸,max随TOM含量的增加而增大,当TOM含量相当时,则随沉积物ASOM含量的增加而降低,再吸附强度随沉积物中LFOM含量的增加而降低.沉积物磷吸附释放容量随有机质总量的增加而增加,吸附释放平衡浓度随有机质活性的增加而降低,释放强度和速率随有机质分解程度的增加而降低,吸附强度和速率随有机质活性的增加而增加.     

不同降水下覆盖与缓释肥减量对油菜土壤微生物群落结构的影响

为探讨沟垄集雨、秸秆覆盖和减量缓释肥集成技术对油菜土壤微生物群落结构的影响,在大田定位试验条件下,设置3种栽培方式（秸秆覆盖、沟垄集雨、传统平作）和4种施肥水平（习惯施肥、缓释肥减量20%、缓释肥减量40%、不施肥）,比较分析2016~2017年（多雨年份）和2017~2018年（季节性干旱年份）这2种不同降水年型下油菜土壤微生物群落结构对集成技术的响应.结果表明,不同降雨条件下,秸秆覆盖+缓释肥减量20%（J80）与沟垄覆盖+缓释肥减量20%（M80）较习惯栽培（PC）更利于土壤微生物生长.在多雨年型和季节性干旱年型下,J80与M80能平均分别提高微生物量碳9.94%和10.32%;提高土壤微生物量氮2.38%和1.19%.多雨年型下,土壤微生物磷酸脂肪酸（PLFA）总量较干旱年型降低30.75%,覆盖能有效提高土壤PLFA质量摩尔浓度.多雨年型下土壤细菌、真菌PLFA质量摩尔浓度较干旱年型平均减少33.67%和53.21%;而放线菌PLFA增加13.04%.微生物群落对异常降水具有敏感响应.多雨气候会造成细菌/真菌升高;干旱气候则会增加直链饱和脂肪酸/直链单不饱和脂肪酸及直链单不饱和脂肪酸/环丙烷脂肪酸.通过秸秆覆盖与缓释肥的集成技术,能稳定异常降水下的土壤微环境,缓解水分和养分胁迫,为油菜稳产和可持续发展提供有效途径.     

底泥污染物释放动力学研究

采用模拟试验方式和新型微生物数量测定方法 ,研究了沼泽化湖泊底泥和受污染河流底泥在不同扰动状态下 ,底泥耗氧速率、氮和磷污染物释放动力学过程。结果表明 :( 1)底泥耗氧速率是同样条件下上覆水耗氧速率的 48倍 ,而在扰动状态下 ,底泥耗氧速率达到上覆水耗氧速率的 5 96— 93 6倍 ,扰动底泥显著增大其耗氧速率 ,底泥污染越严重 ,其耗氧速率越大 ,对水体产生的影响也越大。 ( 2 )扰动底泥可以显著增大底泥的氮磷释放速率 ,氮的释放受有机氮的氨化、氨氮的硝化、硝酸盐氮的反硝化以及氨氮被微生物吸收转化为有机氮等的影响 ;磷的释放过程受厌氧过程和底泥颗粒吸附的影响 ,耗氧速率高的底泥具有更大的氮磷释放潜力。 ( 3 )微生物数量在底泥污染物释放动力学中起着关键性作用 ,新型方法可以快速检测微生物总量。试验结果对于水环境的管理、受污染水体的修复 ,以及底泥的处理处置等都具有重要的指导意义     

湖泊内源氮磷污染分析方法及特征研究进展

湖泊的内源氮磷污染已成为湖泊富营养化治理的一大难题.本文总结了沉积物中氮磷赋存形态、沉积物-水界面氮磷迁移释放行为和沉积物中氮磷的生物有效性三方面的研究进展,提出了目前研究存在的问题,并对未来发展趋势和研究方向进行了展望,以期为湖泊内源氮磷污染机理分析和湖泊富营养化治理控制技术提供参考.     

Experimental investigation on shock waves generated by pressurized gas release through a tube

An experimental investigation on the flow structures and the strength of shock waves generated by high-pressure gas release through a tube into air was conducted. The results demonstrated that a leading shock wave was generated in front of the compressed gas jet and the shock wave speed increased firstly, then decreased and finally kept constant with an increase of the propagation distance in the tube. The experimentally measured Mach numbers of shock waves were close to those calculated from the theory of ideal shock tube flow. After spouting out of the tube, the normal shock quickly developed into a hemispherical shape. The Mach disk was observed in the under-expanded jet. For high-pressure combustible gas release, the concept of theoretical critical pressure of ignition was introduced and several theoretical critical pressures of common gaseous fuels were obtained.     

Effects of Nitrate Nitrogen Additions on Physical, Chemical and Biological Parameters in Lake Enclosures

The effects of nitrate additions on the physics, chemistry and biology of lake water were studied in 5 × 10 m polyethylene enclosures installed in Lake Kastoria, a shallow eutrophic lake in Northern Greece. The water physics, chemistry, chlorophyll a and nitrogenase activity were monitored from July 10 till October 17 1985 at 2 week intervals. The experiment included a control enclosure.

Water confinement in the control enclosure resulted in ammonia accumulation, a slight decrease in chlorophyll a, a significant reduction of nitrogenase activity and an increase in phosphorus release from the sediments at the end of the experimental period.

The addition of KNO₃ resulted in higher than the control accumulation of NH₃, chlorophyll reduction, increase in water transparency and reduction of nitrogenase activity. Large losses of nitrogen added were measured which were attributed to denitrification, organic matter sedimentation and ammonia volatilization. Anaerobic but not aerobic phosphorus release from sediments was inhibited at the end of the period. The reduction of nitrogenase activity and of chlorophyll a concentration are attributed to changes in phytoplankton composition from blue-greens to small-sized species grazed by zooplankters.     

Kinetic analysis of anaerobic phosphorus release during biological phosphorus removal process

Enhanced biological phosphorus removal (EBPR) is a commonly used and sustainable method for phosphorus removal from wastewater. Poly-β-hydroxybutyrate (PHB), polyphosphate, and glycogen are three kinds of intracellular storage polymers in phosphorus accumulation organisms. The variation of these polymers under different conditions has an apparent influence on anaerobic phosphorus release, which is very important for controlling the performance of EBPR. To obtain the mechanism and kinetic character of anaerobic phosphorus release, a series of batch experiments were performed using the excessively aerated sludge from the aerobic unit of the biological phosphorus removal system in this study. The results showed that the volatile suspended solid (VSS) had an increasing trend, while the mixed liquid suspended sludge (MLSS) and ashes were reduced during the anaerobic phosphorus release process. The interruption of anaerobic HAc-uptake and phosphorus-release occurs when the glycogen in the phosphorus-accumulating-organisms is exhausted. Under the condition of lower initial HAc-COD, HAc became the limiting factor after some time for anaerobic HAc uptake. Under the condition of higher initial HAc-COD, HAc uptake was stopped because of the depletion of glycogen in the microorganisms. The mean ratio of Δρ _P/Δρ _PHB, Δρ _GLY/Δρ _PHB, Δρ _P/ΔCOD, was 0.48, 0.50, 0.44, and 0.92, respectively, which was nearly the same as the theoretical value. The calibrated kinetic parameters of the HAc-uptake and phosphorus-release model were evaluated as follows: Q _HAc,max was 164 mg/(g · h), Q _P,max was 69.9 mg/(g · h), K _gly was 0.005, and KCOD was 3 mg/L. An apparently linear correlation was observed between the ratio of Δρ _P/ΔCOD and pH of the solution, and the equation between them was obtained in this study. Translated from Acta Scientiae Circumstantiae, 2005, 25(9), 1164–1169 [译自: 环境科学学报]     

应用pH—ORP计自动控制液氯氧化含氰废水

排放量较大的含氰电镀废水,在碱性氯化法处理中以液氯为氧化剂,用PH—ORP计自动控制反应条件和反应终点。该方法自动化程度高,处理效果较好,运行费用低。     

包气带中残油动态释放实验研究

通过对下水油类浓度、水位、降雨量及色质联机分析，确定了包气带中残油为水源地主要污染源之一，利用动态释放试验。模拟了河滩包气油污土层中残油动态释放过程，探讨了不同水深及间歇进地油类释放的影响并确定残油的污染能力。