Rhizosphere effect of different aquatic plants on phosphorus depletion

A series of pot experiments with Alternanthera philoxeroides, Typha latifolia, Sagittaria sagittifolia and Phragmites communis were conducted to assess the phosphorus depletion effect in the rhizosphere. The ratio of root to shoot, root morphology, phosphorus uptake efficiency and phosphorus utilization efficiency were analyzed. An obvious variation in phosphorus concentrations between the rhizosphere soil and non-rhizosphere soil was observed. The water-soluble P contents in the rhizosphere soil of A. philoxeroides, T. latifolia, S. sagittifolia and P. communis were reduced by 81%, 42%, 18% and 16%, respectively, compared with that in the non-rhizosphere soil. A. philoxeroides had the highest phosphorus uptake efficiency (1.32 mg/m), while T. latifolia achieved the effective phosphorus depletion by the strong rooting system and the high phosphorus uptake efficiency (0.52 mg/m). T. latifolia not only used phosphorus to produce biomass economically, but also adjusted carbon allocation to the roots to explore the soil for more available phosphorus. A. philoxeroides and T. latifolia were more effective in depleting phosphorus in the rhizosphere than S. sagittifolia and P. communis.     

化学除磷条件下蚯蚓生态滤池污泥性质的试验研究

概述了蚯蚓生态滤池的研究进展,介绍了蚯蚓生态滤池化学除磷的工艺流程和设备参数;由试验得出氯化铁（FeCl3·6H2O）是蚯蚓生态滤池化学除磷的合适药剂,并确定最经济投加量为50mg／L;在此条件下,研究了化学除磷小试滤池产生的污泥性质,包括污泥产率的变化、重金属含量、污泥的脱水性能、污泥的稳定化程度以及污泥的最终处置方法。     

生物陶粒——硅藻土联合工艺脱氮除磷

试验采用硅藻土和生物接触氧化组合工艺处理污水处理厂出水,氨氮从10mg／L下降到0．5mg／L以下,去除率70～95％;硅藻土澄清池对总磷的去除率高于95％;且对浊度、色度均有良好的去除效果。     

丰水期鄱阳湖氮磷含量变化及来源分析

通过系统测定丰水期鄱阳湖湖水、主要支流水、长江水及部分农田水、地下水及城市污水的氮磷含量,对其氮磷含量变化及来源进行了分析,结果表明,鄱阳湖水体中主要的氮素形式是硝酸盐氮（090 mg/L）,赣江是其主要贡献者。鄱阳湖五大支流氮磷含量存在着较大的差异,赣江NO-3 N含量明显高于鄱阳湖其它主干流,而NH+4 N和TN含量以饶河的最高,TP以信江的最高。农田水、城市废水以及地下水含有较高的氮磷含量,是鄱阳湖及其五大支流氮磷的主要来源。农田水TN和TP含量最高,分别为1347、2863 mg/L。高含量的NO-3 N（735 mg/L）和NH+4 N（548 mg/L）分别出现在地下水和城市污水中。鄱阳湖水体氮负荷较大,N/P比值远大于7〖DK〗∶1。受滞留区及赣江和修水补给的影响,鄱阳湖主河道氮含量变化从上游至下游呈总体上升趋势。鄱阳湖湖体氮含量以下游最高,滞留区次之,上游主河道最低,TP含量呈相反的趋势变化。底层沉积有机物的降解和扰动导致鄱阳湖水体底层NO-3 N、NH+4 N、TN、TP的含量高于表层。     

Simulating mesoscale transport and diffusion of radioactive noble gases using the Lagrangian particle dispersion model

In order to simulate the impact of mesoscale wind fields and to assess potential capability of atmospheric Lagrangian particle dispersion model (LPDM) as an emergency response model for the decision supports, two different simulations of LPDM with the mesoscale prognostic model MM5 (Mesoscale Model ver. 5) were driven. The first simulation of radioactive noble gas ((85)Kr exponent) emitted during JCO accident occurred from 30 September to 3 October 1999 at Tokai, Japan showed that the first arriving short pulse was found in Tsukuba located at 60km away from the accidental area. However, the released radioactive noble gas was transported back to the origin site about 2 days later due to the mesoscale meteorological wind circulation, enhancing the levels of (85)Kr with the secondary peak in Tsukuba. The second simulation of atmospheric dilution factors (the ratio of concentration to the emission rate, chi/Q), during the underground nuclear test (UNT) performed by North Korea showed that high chi/Q moved to the eastward and extended toward southward in accordance with the mesoscale atmospheric circulations generated by mesoscale prognostic model MM5. In comparison with the measurements, the simulated horizontal distribution patterns of (85)Kr during the JCO are well accord with that of observation in Tsukuba such as the existence of secondary peak which is associated with the mesoscale circulations. However, the simulated level of (85)Kr anomaly was found to be significantly lower than the observations, and some interpretations on these discrepancies were described. Applications of LPDM to two mesoscale emergency response dispersion cases suggest the potential capability of LPDM to be used as a decision support model provided accurate emission rate of accident in case of a large accident.     

Runoff variation affected by precipitation change and human activity in Hailiutu River basin,China

For recent years, runoff generation and hydrological processes in Hailiutu River basin have been greatly changed by climate change and human activity, especially water and soil conservation construction. In this study, the trends in precipitation, evapotranspiration (ET) and river runoff as well as the effects of precipitation change and human activity on runoff variation have been studied. The results showed that during 1960–2000, annual precipitation and river runoff, monthly precipitation and ET in September and October as well as monthly runoff in all months showed a significant decrease. In addition, peak flow and base flow had a large decrease. Under the joint influence of precipitation change and human activity, the mean annual runoff decreased by 35 million m³ from the baseline period (1960–1985) to the change period (1986–2000), which accounted for 60.9% and 39.1% of the total runoff decrease, respectively. Precipitation change played a primary role in the decrease of annual runoff whereas human activity, particularly water and soil conservation construction, also had remarkable impacts on runoff variation.     

Effect of Earthworm(Pheretima sp.) Density on Revegetation of Lead/zinc Metal Mine Tailings Amended with Soil

Abstract

The objective of this study was to investigate the effects of earthworm density on the availability of nutrients and heavy metals in metal contaminated soils. Pb/Zn mine tailings were mixed throughly with a red yellow podzolic soil at the ratio (w/w) of 75:25. Earthworms (Pheretima sp.) were introduced to the mixture at four different densities, zero, three, six and nine individuals per pot planted with ryegrass (Loliun multiflorum). The results indicated that earthworm activity significantly enhanced ryegrass shoot biomass. However, as denser earthworm population was introduced, shoot biomass tended to decrease. Earthworm activity significantly increased soil pH and availability of N, P and K in the tailings and soil mixture. There was a general tendency that uptake of Zn by ryegrass increased after earthworm inoculation, although the increase in extractable Zn in tailings and soil mixture was not significant. On the contrary, there seemed to be a lower uptake of Pb by ryegrass under earthworm inoclation, despite the fact that higher extractable Pb concentrations were observed. The present project indicated that the improved growth of ryegrass was due to improved nutrient availability and other soil conditions, by inoculation of earthworms at an appropriate rate. Further studies are needed to illustrate the relationship between metal availability and earthworm activity in the field.     

生态沟渠-生物滞留池组合控制农村径流污染

生态沟渠和生物滞留池因其良好的径流污染控制能力和生态效益,日益受到广泛关注和应用,但单一的生态沟渠或生物滞留池在农村径流污染控制中常存在氮磷去除效果不稳定和基质易堵塞等问题.将两者串联构建组合系统,利用生态沟渠预处理去除部分污染物,可降低生物滞留池污染负荷和减轻基质堵塞;同时在生物滞留池中设置淹没区并添加天然载体碳源提升系统脱氮效果.研究了载体碳源、降雨强度和干湿交替等条件对生态沟渠-生物滞留池组合系统控制农村径流污染的影响.结果表明,投加稻草和木屑两种天然载体碳源分别将生物滞留池段的TN去除率提升19.9%和20.4%.模拟降雨强度从小雨增至大雨时,外加碳源组合系统COD、 NH⁺₄-N、 TN和TP去除率平均下降17.0%、 16.8%、 20.4%和17.2%,其中生态沟渠段对4种污染物的去除贡献平均降低16.3%、 13.0%、 24.2%和22.1%.干湿交替运行可提高系统的污染物去除效果,相较连续进水,干旱3周后木屑组TN平均去除率提升12.3%.微生物群落分析结果显示,木屑组和稻草组生物滞留池样品的α多样性高于对照组;投加载体碳...     

Mg-La-Fe/沸石复合材料的制备及其处理低浓度含磷废水的性能

以沸石为载体,选用镁、镧和铁为改性剂,采用水热法制备了一种新型高效且易于磁性分离回用的载镧磁性沸石吸附剂（MLFZ）.等温吸附和动力学研究结果表明,其吸附行为符合Langmuir等温模型和准二级动力学模型,MLFZ饱和吸附量为13.46 mg·g^-1; MLFZ在pH为3～9范围内均表现出良好的吸附性能,共存离子条件下对磷酸根具有特异吸附能力,通过磁性吸附重复使用5次后,MLFZ对磷酸盐去除率维持在90%左右,突显了其易于回收再利用的优点;FTIR、 XPS和Zeta电位表征显示,表面沉积、静电吸附作用和镧与磷酸盐通过配体交换形成内层络合物在吸附过程中为主要作用.将MLFZ用于处理自然池塘污水,结果显示磷酸盐浓度由0.86 mg·L^-1降低到0.013 mg·L^-1,表明该吸附剂具有良好的实际应用前景.     

不同生物炭对磷的吸附特征及其影响因素

为了实现植物生物质资源化利用,选择5种生物质材料制备生物炭,通过比较5种生物炭材料的磷吸附能力,筛选出了2种磷吸附效果较佳的材料,并探明了筛选生物炭材料的理化性质及其对磷的吸附特征.结果表明,5种生物炭材料中,仅水稻秸秆和玉米秸秆生物炭对磷具有吸附能力.Langmuir等温吸附曲线表明,水稻秸秆生物炭对废水中磷的吸附能力强于玉米秸秆生物炭,理论最大吸附量为：水稻秸秆生物炭(9.78 mg·g^-1)>玉米秸秆生物炭(0.39 mg·g^-1).水稻秸秆生物炭的比表面积(148.30 m²·g^-1)和总孔体积(0.11 cm³·g^-1)远高于玉米秸秆生物炭8.26 m²·g^-1和0.03 cm³·g^-1,同时水稻秸秆生物炭有更高的Mg、 Ca、 Fe和Al元素含量.水稻秸秆生物炭和玉米秸秆生物炭对磷吸附的最佳pH为酸性;在不同的pH范围内（3.0～11.0）,水稻秸秆生...