农业活动与水质的关系研究综述

农业活动与水质的关系十分密切。过量施用化肥、农药等不合理的农业活动常引起氮、磷等营养元素在土壤中富集,进而导致地表水富营养化和地下水硝酸盐污染。     

A VUV photoionization mass spectrometric study on the OH-initiated photooxidation of isoprene with synchrotron radiation

The gas-phase organic compounds resulting from OH-initiated photooxidation of isoprene have been investigated on-line by VUV photoionization mass spectrometry based on synchrotron radiation for the first time. The photoionization efficiency curves of the corresponding gaseous products as well as the chosen standards have been deduced by gating the interested peaks in the photoionization mass spectra while scanning the photon energy simultaneously, which permits the identification of the pivotal gaseous products of the photooxidation of isoprene, such as formaldehyde (10.84 eV), formic acid (11.38 eV), acetone (9.68 eV), glyoxal (9.84 eV), acetic acid (10.75 eV), methacrolein (9.91 eV), and methyl vinyl ketone (9.66 eV). Proposed reaction mechanisms leading to the formation of these key products were discussed, which were completely consistent with the previous works of different groups. The capability of synchrotron radiation photoionization mass spectrometry to directly identify the chemical composition of the gaseous products in a simulation chamber has been demonstrated, and its potential application in related studies of atmospheric oxidation of ambient volatile organic compounds is anticipated.     

缺氧生物吸附活性污泥法生物脱氮工艺中试研究

结合生物作用机理,提出缺氧生物吸附活性污泥法生物脱氮（ABSAS工艺）工艺,在小试的基础上,进行了中试研究。结果表明,通过强化缺氧吸附作用可提高反硝化作用速率,在仅有污泥回流而无硝化混合液回流的前提下,TN去除仍可达60％～80％。在冬季（8～13℃）进水NH^＋₄－N60mg/L左右、HRT10小时时,NH^＋₄－N去除率达88％以上,出水小于15mg/L。此工艺具有很好的工业应用前景,可在设备投资增加不大的情况下,实现将传统活性污泥法工艺改造为具有生物脱氮功能的工艺     

氯苯类同系物共基质条件下相互作用研究

通过分析贡献因子的方法,研究氯苯类同系物在驯化污泥中同系物共基质条件下的耗氧速率,结果表明,氯苯类同系物共基质条件下存在的相互作用包括竞争,抑制、诱导及共代谢等,有机物间的相互作用受驯化污泥的影响较大,即使对于２种相同的有机物,经污泥不同,作用机制也不相同。     

好氧颗粒污泥的形成过程及其影响因素

阐述了以普通活性污泥和厌氧颗粒污泥为接种物时好氧颗粒污泥的形成过程,以及细胞表面较高的疏水性,基质中适当的Ca2+浓度,反应器内较高的水流剪切力和较短的沉降时间对这一过程的促进作用。     

厌氧酸化在焦化废水脱氮和毒性削减中的作用

分别用厌氧酸化-缺氧-好氧(A₁-A₂-O)生物膜法和缺氧-好氧(A/O)生物膜法处理焦化废水,比较了二者对废水毒性的削减效果.试验结果表明,焦化废水的毒性大于0.19mg/L氯化汞的毒性.其毒性削减与有机氮去除有一定关系,厌氧酸化在提高废水有机氮去除率和降低废水的毒性方面起到了重要的作用.废水经A₁-A₂-O生物膜系统处理后,毒性大大降低,当HRT为37.9h时,出水对发光菌的相对发光度可达96.8%,其毒性相当于0.023mg/L氯化汞的毒性.     

Impact of different benthic animals on phosphorus dynamics across the sediment-water interface

As a diagenetic progress, bioturbation influences solute exchange across the sediment-water interface (SWI). Different benthic animals have various mechanical activities in sediment, thereby they may have different effects on solute exchange across the SWI. This laboratory study examined the impacts of different benthic animals on phosphorus dynamics across the SWI. Tubificid worms and Chironomidae larvae were introduced as model organisms which, based on their mechanical activities, belong to upward-conveyors and gallery-diffusers, respectively. The microcosm simulation study was carried out with a continuous flow culture system, and all sediment, water, and worms and larvae specimens were sampled from Taihu Lake, China. To compare their bioturbation effects, the same biomass (17.1 g wet weight (ww)/m2) was adopted for worms and larvae.Worms altered no oxygen penetration depth in sediment, while larvae increased the O2 penetration depth, compared to the control treatment. Their emergence also enhanced sediment O2 uptake. The oxidation of ferrous iron in pore water produced ferric iron oxyhydroxides that adsorbed soluble reactive phosphorus (SRP) from the overlying water and pore water. Larvae built obviously oxidized tubes with about 2 mm diameter and the maximum length of 6 cm in sediment, and significantly decreased ferrous iron and SRP in the pore water compared to the control and worms treatments. Worms constructed no visually-oxidized galleries in the sediment in contrast to larvae, and they did not significantly alter SRP in the pore water relative to the control treatment. The adsorption of ferric iron oxyhydroxides to SRP caused by worms and larvae inhibited SRP release from sediment. Comparatively, worms inhibited more SRP release than larvae based on the same biomass, as they successively renewed the ferric iron oxyhydroxides rich oxidation layer through their deposition.     

中空纤维膜生物反应器处理生活污水的特性

中空纤维膜生物反应器生活污水处理特性的试验研究结果表明：Ｄ ＨＲＴ为１．５ｈ,ＣＯＤ容积负荷为５．７６ｋｇ／（ｍ＾３·ｄ）条件下,均可实现９０％以上的ＣＯＤ去除率;对ＮＨ３－Ｎ的去除率可稳定在９０％以上,高ＭＬＳＳ浓度８０００－１００００ｍｇ·Ｌ）提供了内部厌氧环境,使膜生物反应器的Ｔ－Ｎ去除率可达５０－６０％,中空纤维生物反应器处理高效,不受冲击负荷影响,操作管理方便,其生活物反应器体积比常规生     

太湖风生流水动力时空差异特征研究

为研究太湖的流场结构,更好实施引清调水方案改善太湖水质。在确定太湖四季主导风向及其平均风速的基础上,采用有限体积Godunov型通量差分裂(FDS)格式构建太湖水动力模型,并得到了实测流场的良好验证。并进一步研究各季节各湖区的流动规律,确定太湖风生流水动力时空差异特征。结果表明:太湖风生流流态特征主要与风向、风速有关;不同季节平均流速由大到小分别为:冬季、春季、秋季、夏季;从不同的湖区看,湖岸区最大、湖湾区次之、湖心区最小。由此可选择冬季、湖岸区实施调水方案改善太湖水质。     

Chemical characterization of size-resolved aerosols in four seasons and hazy days in the megacity Beijing of China

Size-resolved aerosol samples were collected by MOUDI in four seasons in 2007 in Beijing. The PM10 and PM1.8mass concentrations were 166.0 ± 120.5 and 91.6 ± 69.7 μg/m~3, respectively,throughout the measurement, with seasonal variation: nearly two times higher in autumn than in summer and spring. Serious fine particle pollution occurred in winter with the PM1.8/PM10 ratio of 0.63, which was higher than other seasons. The size distribution of PM showed obvious seasonal and diurnal variation, with a smaller fine mode peak in spring and in the daytime. OM(organic matter = 1.6 × OC(organic carbon)) and SIA(secondary inorganic aerosol) were major components of fine particles, while OM, SIA and Ca_2+were major components in coarse particles. Moreover, secondary components, mainly SOA(secondary organic aerosol) and SIA,accounted for 46%–96% of each size bin in fine particles, which meant that secondary pollution existed all year. Sulfates and nitrates, primarily in the form of(NH_4)_2SO_4, NH_4NO_3, Ca SO_4, Na_2SO_4 and K_2SO_4, calculated by the model ISORROPIA II, were major components of the solid phase in fine particles. The PM concentration and size distribution were similar in the four seasons on non-haze days, while large differences occurred on haze days, which indicated seasonal variation of PM concentration and size distribution were dominated by haze days. The SIA concentrations and fractions of nearly all size bins were higher on haze days than on non-haze days, which was attributed to heterogeneous aqueous reactions on haze days in the four seasons.