常见沉水植物对草海水体(含底泥)总氮去除速率的研究

利用狐尾藻?菹草?苦草?伊乐藻?金鱼藻?篦齿眼子菜?轮藻等7种沉水植物对受污染的草海水体(含底泥)总氮去除速率进行了试验研究?结果表明:每种沉水植物对水体总氮?总磷均有显著去除作用,在试验的27d内,对总氮?总磷的去除百分率分别为80.31%,89.82%;重点对7种沉水植物引起水体总氮浓度下降与时间的关系作回归分析,所得结果是随着时间的延长,水体中总氮浓度呈负指数形式衰减?该文还研究了水体总氮浓度与去除速率之间的关系?每种沉水植物在试验的总氮浓度范围内(2.628～16.667mg/L)去除速率随总氮浓度的增加而增加?对TN_{_t}曲线和V-TN曲线在大型水生植物系统恢复中的应用进行了讨论?      

淀山湖沉水植物死亡分解过程中营养物质的释放

测定了上海淀山湖5种常见沉水植物的营养成分含量及其死亡后在好氧(DO>3.5 mg/L)或低氧(DO<3.5 mg/L)状态下分解释放TN、TP和有机物(以高锰酸盐指数计,下同)等营养物质的动态过程,并对营养物质释放强度与营养成分含量的相关性进行了分析.结果表明, 5种沉水植物中,金鱼藻的TN和TP含量最高,质量分数分别为(4.07±0.22)%和(0.99±0.09)%;好氧状态下TN和有机物的释放强度大于低氧状态,两种状态下TP的释放强度没有显著差异;TP的释放比TN快,一般需10 d左右,而TN和有机物的释放分别需要29 d和20 d左右;在好氧状态下,NO-2-N、NO-3-N和可溶性总磷酸盐的平均释放强度与植物TN含量呈显著正相关(p<0.05),NH 4-N的平均释放强度与植物TP含量呈显著正相关(p<0.05);在低氧状态下,NO-2-N的平均释放强度与植物TN含量、NO-3-N的平均释放强度与植物TP含量分别呈显著正相关(p<0.05);有机物的平均释放强度与植物TP含量呈极显著负相关(p<0.01).     

水源水中典型除草剂禾大壮与莠灭净突发污染的应急处理

针对被典型除草剂禾大壮与莠灭净污染原水的应急处理工艺进行了研究.结果表明,活性炭吸附和预氯化是有效去除禾大壮和莠灭净的2种措施.拟二级动力学模型和Freundlich吸附等温线模型可分别较好地描述粉末活性炭对原水中禾大壮和莠灭净的吸附过程和吸附平衡.40 mg/L的粉末活性炭可将浓度为200ìg/L的禾大壮或莠灭净污染完全去除,粉末活性炭的最佳投加位置是混凝前20 min,颗粒活性炭柱(高20 cm)对2种农药的去除效果都较为显著,可以作为粉末活性炭的有效补充保证一定的安全系数.有效氯投加量为2.5 mg/L时虽然也可将2种农药氧化去除,但生成的产物及其毒性有待于进一步研究.粉末活性炭与1 mg/L的KMnO4预氧化联用并没有提高禾大壮和莠灭净的去除效果,粉末活性炭与1.5 mg/L的Cl2联用的去除效果与二者投加顺序有关.当浓度均为200 ìg/L左右的禾大壮与莠灭净同时污染原水时,粉末活性炭的投加量增至50 mg/L可将它们完全去除,Cl2的用量提高至3 mg/L可将它们全部氧化.     

大气中酮类化合物污染事故应急监测

研究了大气中低分子量酮类化合物的气相色谱测定方法 ,进行了线性范围、精密度和准确度实验。结果表明 ,该方法具有简便快捷、准确灵敏的特点 ,适合于大气污染事故应急监测     

MACROPHYTE STANDING CROP AND PRIMARY PRODUCTWITY IN SOME FLORIDA SPRING-RUNS1

ABSTRACT: A survey of 31 Florida spring-runs was conducted to estimate their submerged macrophyte standing crop and primary productivity. The standing crops of submerged vegetation were not significantly (p > 0.05) correlated to either total nitrogen (r = 0) or total phosphorus (r =?0.20) concentrations, but standing crops were significantly (p < 0.01) correlated to the percentage of the spring-run's water surface shaded by marginal vegetation (r =?0.76). Maximum daily rates of primary productivity were positively correlated with average submerged macrophyte standing crops (r = 0.81; p < 0.001) and inversely correlated with the degree of shading by marginal vegetation (r =? 0.43; p < 0.05).     

NITROGEN ACCUMULATION IN A CONSTRUCTED WETLAND FOR DAIRY WASTEWATER TREATMENT1

ABSTRACT: A free water surface (FWS) constructed wetland was installed at a dairy in Glendale, Arizona, to study the potential of such a wetland to remove nitrogen (N) from wastewater. The study objectives were: (1) to determine N removal from the wastewater, and (2) to evaluate N accumulation in soil and plant tissues. The system consisted of eight cells (70 × 9 × 1.5 m) planted with Typha domingensis, Scirpus validus, and Phragmites australis. The four cells in series were lined with plastic, and the four cells in a parallel series were lined with clay. Cells received approximately 180 m³/d of partially treated dairy effluent. Plant tissues and soil samples were collected above and below ground from 24 locations during one year. Total N removal from wastewater was about 17 percent. Clay‐lined cells accumulated more N in the soil and less N in plant biomass compared with plastic lined cells. Plant biomass accounted for approximately 60 percent of total N accumulated in cells with dense plant communities. Ninety percent of accumulated soil N was organic. Total N accumulated in soil reached a maximum (1,100 mg/kg) eight months after the introduction of wastewater.     

MODELING TO EVALUATE MACROPHYTE INDUCED IMPACTS TO DISSOLVED OXYGEN IN A TAILWATER RESERVOIR1

ABSTRACT: Effects of aquatic macrophytes are not considered in most standard water quality models. This study used field measurements and water quality models to help determine the effects of aquatic macrophytes on dissolved oxygen (DO) concentrations in a shallow tailwater reservoir. Installation of a hydropower plant and macrophytes (primarily Potamogeton and Chara) in a large shallow portion of the lake are possible causes of reduced DO levels in the tailwater reservoir. A water quality model (WASP5) was used to quantify the various DO sources and sinks and to evaluate the effects of the hydropower operations on DO levels in the lake. It was found that the macrophytes in Lake Ogallala had a significant effect on the DO levels in the lake. At an average macrophyte density of about 6,360 g/m² (wet weight) in 2000, the DO fluctuated daily from about 3 mg/l to about 12 mg/l. At an average macrophyte density of about 2,120 g/m² (wet weight) in 2002, the DO fluctuated from about 5 mg/l to about 9 mg/l daily. The model predicted that the DO would remain near 5 mg/l without macrophytes. The photo‐synthetic and respiration rates developed in the model (4.4 mg/g‐hr and 1.4 mg/g‐hr, respectively) agree well with literature values.     

EFFICACY AND COST OF AQUATIC WEED CONTROL IN SMALL PONDS'

ABSTRACT: Twenty, 0.2 hectare ponds were utilized for a four-year evaluation of three aquatic vegetation control techniques: a combination of inorganic fertilization and mechanical harvesting, aquatic herbicides, and grass carp (Ctenopharyngodon idella). Ponds used for herbicide and grass carp treatments were managed at three levels of aquatic vegetation (none, 40 and 70 percent plant occupation). Submersed vegetation was not controlled with inorganic fertilization. Vegetation levels were maintained for less than 30 days after mechanicai harvesting. Submersed macrophytes were not completely eliminated with herbicides, but the herbicide treatments utilized were effective at maintaining aquatic vegetation above 30 percent pond volume occupation. Grass carp consumed all species of submersed vegetation at the stocking densities used in this study; therefore, planned levels of submersed macrophytes were not maintained. Grass carp did not consume all floating leaf vegetation, but after four years some grass carp ponds did have lower densities of floating leaf plants. Fertilization costs were $608/hectare/year, and mechanical harvesting costs were $1979/hectare/year, resulting in a total aquatic vegetation treatment cost of $2587/hectare/ year. Herbicide costs for the different treatment levels ranged from $417/hectare/year to $1339/hectare/year over the four-year period. Grass carp were the most economical vegetation control measure tested, with costs ranging from $159/hectare/year to $248/hectare/year for the four-year study.     

预氯化工艺去除水中氰化物、硫化物及水合肼等还原性污染物研究

以较常见的预氯化为技术手段,考察了预氯化工艺去除饮用水中氰化物、硫化物以及水合肼等还原性污染物的效果和影响因素.结果表明:(1)实验条件下氰化物浓度随有效氯投加量的增加而下降,并在有效氯投加量＞5.0 mg/L时降低到低于《生活饮用水卫生标准》(GB5749-2006)中限值(0.05mg/L),在有效氯投加量＞6.0...     

饮用水源水无机金属污染的应急处理

根据密云水库供水现状,针对突发性无机金属污染事件,采用聚合氯化铝辅助化学沉淀法进行应急处理。选用Cu2＋、Fe2＋、Zn2＋和Cd2＋ 4种金属离子为目标污染物,首先通过小试实验确立了最佳混凝处理条件。结果表明,调节pH值为8．0左右,可使初始浓度为5mg／L和10mg／L的Cu2＋浓度降至0．96mg／L和0．67mg／L;初始浓度为1．5mg／L和3mg／L的Fe2＋浓度降至0．27mg／L和0．24mg／L;初始浓度为0．05mg／L和0．1mg／L的Cd2＋浓度降为0．0089mg／L和0．0078mg／L;调节pH值为9．0时,可使初始浓度为5mg／L和10mg／L的Zn2＋浓度降至0．57mg／L和0．48mg／L。4种污染物出水浓度均低于国家饮用水标准。在小试基础上,在北京第九水厂开展无机金属污染处理的中试实验,结果表明所选用的聚合氯化铝辅助化学沉淀法简便易行,可实现污染物快速、有效去除。