荧光分光光度法测定天然水中的挥发酚

天然水经过蒸馏后,直接用荧光分光光度计进行测定。激发波长为２７５ｎｍ,最佳发射波长为２９８ｎｍ,可定量测定水中的挥发酚。该方法灵敏、准确、节省试剂、简便易行,方法最低检出限可达２μｇ／Ｌ     

三峡库区消落带受淹土壤氮和磷释放的模拟实验

三峡库区消落带形成后,消落带土壤淹水初期将向上覆水释放氮和磷. 将消落带土壤样品进行加肥处理后与原始土壤进行模拟淹水实验.对原始土壤进行每日换水浸泡实验.结果表明:消落带进入淹水期10～15 d后,其上覆水中营养物含量趋于平衡,水体扰动对上覆水中ρ(TP)和ρ(TN)有正影响. 未经施肥处理的消落带土壤在江水浸泡下,对TP有吸附作用,使得浸泡结束后ρ(TP)下降33.4%. TN的溶出速率变化能较好地符合一级动力学方程,TP江水静态浸泡实验数据对一级动力学方程的拟合性较差;TP和TN的绝对溶出速率对一级动力学方程的相关性均较好.       

流量对三峡库区嘉陵江重庆主城段藻类生长的影响

对于三峡库区,大部分一级支流都具备产生富营养化的营养水平,在水温和光照等气候条件适宜藻类生长的3—5月,水文条件成为影响藻类生长繁殖和诱发富营养化的关键因素.3—5月恰是水库坝前泄水的消落时段,水文条件与一般的湖泊、河流和水库等显著不同. 针对三峡水库特殊的水文情势, 通过现场水质采样,应用质量守恒原理,研究了3—5月上游来水流量对嘉陵江重庆主城段藻类生长的影响. 结果表明:流量对河段的藻类密度和质量净增量有显著影响,3月因较低的来水流量和较小的大坝泄水量使藻类密度和质量净增量最大,5月当流量接近或超过历史同期水平时,河段的藻类质量净增量为负,而当流量偏枯较大时,藻类质量净增量为正.      

三峡库区石盘丘小流域氮磷输出形态及流失通量

小流域作为三峡库区非点源污染源头,是缓解水体水质恶化的重点防控对象.在三峡库区选取具有多种土地利用类型的石盘丘小流域为研究对象,对流域出水口断面水量水质进行连续监测,分析了小流域氮、磷污染物随降雨径流流失的浓度及形态变化特征,并计算小流域的污染物流失通量,分析影响氮、磷养分流失的主要人为和自然因素,对农业非点源污染特别是三峡库区的农业非点源污染研究具有相当重要的现实意义.结果表明,流域降雨量随季节变化明显,降雨多分布在4～6月,为小流域氮、磷流失的主要输出时期,占全年总氮、总磷负荷的58.94%和67.60%.石盘丘小流域年径流总量为8.02×10⁴ m³,总氮年流失通量为5.04 kg·hm^-2,其中以硝态氮(2.54 kg·hm^-2)为流失主体;输出总磷为0.534 kg·hm^-2,可溶性总磷(0.422kg·hm^-2)占总磷流失通量的79.00%.因此,对于石盘丘小流域来说,需要注意防范施肥和降雨期重合时水田氮磷流失.     

三峡水库干流氮和磷含量的季节变化

三峡水库成库后对6个水平断面、4个垂直断面采样分析,对水体水质参数、不同化学形态N以及不同物理形态P的水平分布和垂直分布进行了研究。研究结果表明,成库后TP、NH3-N、NO2--N、NO3--N、IN含量范围分别在0.06～0.34、0.01～0.72、0.002～0.100、0.76～2.09、0.855～2.52 mg/L。TP分布为丰水期>平水期>枯水期,受悬浮物沉降的影响,TP在水库区域含量低于上游区。枯水期、平水期水体中TP以可溶解态为主,丰水期以颗粒态为主。NO2--N、NO3--N、IN含量均为平水期>枯水期>丰水期。水体中IN以NO3--N为主,占IN70%～90%。NO2--N比例最低,占IN3.5%以下。表明水体虽受成库影响流速减缓,但水体依然有较强的自净能力。垂直分布上,TP、IN在3个层次变化不显著,未出现分层现象。各采样站点TP、NO3--N、IN通量和流量有显著相关。     

三岔湖浮游植物四季群落结构变化

2008年5月—2009年4月对三岔湖浮游植物群落结构进行调查的结果显示,浮游植物有8门78属299种,浮游生物群落结构、优势种和密度有明显的季节变化。春末和夏季蓝藻占绝对优势,冬季和初春硅藻和绿藻占优势。浮游植物优势种有梅尼小环藻(Cyclotella meneghiniana)、尖针杆藻(Synedra acus Kutzing)、小舟形藻(Naviculaminima)、细小平裂藻(M erism opdeia minima)、湖泊鞘丝藻(Lyngbya lim netia)等。浮游植物优势种群和密度显示,湖区的水体已进入富营养状态。     

Characteristics and removal mechanism of the precursors of N-chloro-2,2-dichloroacetamide in a drinking water treatment process at Taihu Lake

• N-Cl-DCAM, an emerging N-DBP in drinking water was investigated. • A new BAC has a better removal efficiency for N-Cl-DCAM precursors than an old BAC. • N-Cl-DCAM precursors are more of low molecular weight and non-polar. • Adsorption of GAC plays a major role in removal of N-Cl-DCAM precursors by an O₃-BAC. N-chloro-2,2-dichloroacetamide (N-Cl-DCAM) is an emerging nitrogenous disinfection by-product (N-DBP) which can occur in drinking water. In this study, an analytical method based on liquid chromatography with tandem mass spectrometry (LC-MS/MS) was developed to validate the concentration of N-Cl-DCAM, which was found to be 1.5 mg/L in the effluent of a waterworks receiving raw water from Taihu Lake, China. The changes of N-Cl-DCAM formation potential (N-Cl-DCAMFP) in the drinking water treatment process and the removal efficiency of its precursors in each unit were evaluated. Non-polar organics accounted for the majority of N-Cl-DCAM precursors, accounting for 70% of the N-Cl-DCAM FP. The effect of conventional water treatment processes on the removal of N-Cl-DCAM precursors was found to be unsatisfactory due to their poor performance in the removal of low molecular weight (MW) or non-polar organics. In the ozonation integrated with biological activated carbon (O₃-BAC) process, the ozonation had little influence on the decrease of N-Cl-DCAM FP. The removal efficiency of precursors by a new BAC filter, in which the granular activated carbon (GAC) had only been used for four months was higher than that achieved by an old BAC filter in which the GAC had been used for two years. The different removal efficiencies of precursors were mainly due to the different adsorption capacities of GAC for individual precursors. Low MW or non-polar organics were predominantly removed by GAC, rather than biodegradation by microorganisms attached to GAC particles.     

Application of Fe(VI) in abating contaminants in water: State of art and knowledge gaps

• The properties of Fe(VI) were summarized. • Both the superiorities and the limitations of Fe(VI) technologies were discussed. • Methods to improve contaminants oxidation/disinfection by Fe(VI) were introduced. • Future research needs for the development of Fe(VI) technologies were proposed. The past two decades have witnessed the rapid development and wide application of Fe(VI) in the field of water de-contamination because of its environmentally benign character. Fe(VI) has been mainly applied as a highly efficient oxidant/disinfectant for the selective elimination of contaminants. The in situ generated iron(III) (hydr)oxides with the function of adsorption/coagulation can further increase the removal of contaminants by Fe(VI) in some cases. Because of the limitations of Fe(VI) per se, various modified methods have been developed to improve the performance of Fe(VI) oxidation technology. Based on the published literature, this paper summarized the current views on the intrinsic properties of Fe(VI) with the emphasis on the self-decay mechanism of Fe(VI). The applications of Fe(VI) as a sole oxidant for decomposing organic contaminants rich in electron-donating moieties, as a bi-functional reagent (both oxidant and coagulant) for eliminating some special contaminants, and as a disinfectant for inactivating microorganisms were systematically summarized. Moreover, the difficulties in synthesizing and preserving Fe(VI), which limits the large-scale application of Fe(VI), and the potential formation of toxic byproducts during Fe(VI) application were presented. This paper also systematically reviewed the important nodes in developing methods to improve the performance of Fe(VI) as oxidant or disinfectant in the past two decades, and proposed the future research needs for the development of Fe(VI) technologies.     

Zero-valent manganese nanoparticles coupled with different strong oxidants for thallium removal from wastewater

• Nano zero-valent manganese (nZVMn, Mn⁰) is synthesized via borohydrides reduction. • Mn⁰ combined with persulfate/hypochlorite is effective for Tl removal at pH 6-12. • Mn⁰ can activate persulfate to form hydroxyl and sulfate radicals. • Oxidation-induced precipitation and surface complexation contribute to Tl removal. • Combined Mn⁰-oxidants process is promising in the environmental field. Nano zero-valent manganese (nZVMn, Mn⁰) was prepared through a borohydride reduction method and coupled with different oxidants (persulfate (S₂O₈²⁻), hypochlorite (ClO⁻), or hydrogen peroxide (H₂O₂)) to remove thallium (Tl) from wastewater. The surface of Mn⁰ was readily oxidized to form a core-shell composite (MnO_x@Mn⁰), which consists of Mn⁰ as the inner core and MnO_x (MnO, Mn₂O₃, and Mn₃O₄) as the outer layer. When Mn⁰ was added alone, effective Tl(I) removal was achieved at high pH levels (>12). The Mn⁰-H₂O₂ system was only effective in Tl(I) removal at high pH (>12), while the Mn⁰-S₂O₈²⁻ or Mn⁰-ClO⁻ system had excellent Tl(I) removal (>96%) over a broad pH range (4–12). The Mn⁰-S₂O₈²⁻ oxidation system provided the best resistance to interference from an external organic matrix. The isotherm of Tl(I) removal through the Mn⁰-S₂O₈²⁻ system followed the Freundlich model. The Mn⁰ nanomaterials can activate persulfate to produce sulfate radicals and hydroxyl radicals. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggested that oxidation-induced precipitation, surface adsorption, and electrostatic attraction are the main mechanisms for Tl(I) removal resulting from the combination of Mn⁰ and oxidants. Mn⁰ coupled with S₂O₈²⁻/ClO⁻ is a novel and effective technique for Tl(I) removal, and its application in other fields is worthy of further investigation.     

湿式空气非均相催化氧化处理有机废水中难降解有机物的研究

湿式空气催化氧化是曩为经济的环境友好型高级氧化技术之一,在处理有机废水中难降解有机物方面极具前景.为提高氧化效率,钌（Ru）、铑（Rh）、铂（Pt）、钯（Pd）等贵金属及铜（Cu）、铈（Ce）、锰（Mn）、铁（Fe）、镍（Ni）、铝（Al）、铬（Cr）及钴（Co）等金属氧化物等常作为非均相催化剂应用到湿式空气催化氧化体系中.本文对非均相催化湿式空气氧化处理有机废水中难降解有机物的非均相催化剂、工艺条件及反应机理进行了探讨,最后指出了催化剂的失效、解决方法及技术发展方向.