投加硝酸钙对城市黑臭河道底泥氮迁移转化的影响

投加硝酸钙是目前河道黑臭底泥原位治理常用的方法,然而,投加硝酸钙会造成底泥硝态氮和氨氮的过量释放,而其影响机制尚未明确。因此有必要对投加硝酸钙后硝态氮在底泥中的迁移转化规律及其促进氨氮释放的机理进行研究。结果发现,硝酸盐在间隙水的迁移距离取决于硝态氮反硝化速率,而在黑臭底泥中硫化物氧化是影响反硝化速率的关键因素。当硝酸钙投加量为20 g/kg时,硝态氮的迁移距离小于6 cm,且在14 d后消耗光;可见,通过控制硝酸钙在底泥中的投加位置可避免硝态氮的二次释放。另一方面,投加硝酸钙会促进底泥氨态氮向间隙水释放,投加当天释放率可高达101%,且会在间隙水中发生累积迁移。其中,氨氮的增加量和底泥氨态氮解吸量呈一级线性关系(r=0.986)、和硝酸钙投加量关系符合cubic曲线;据此可推测,氨氮的急剧释放与钙离子对底泥铵态氮的化学浸提有关。     

曝气强化微生物功能菌修复黑臭水体

从成都市三道沟黑臭底泥中分离出一株能以底泥有机质为碳源和能源生长的土著微生物功能菌HC-1,经鉴定该菌株为不动杆菌(Acinetobacter)。在实验室条件下,以三道沟黑臭底泥为研究对象,采用微生物功能菌强化底泥有机质降解来修复黑臭水体的方法。研究了底泥曝气和上覆水曝气对黑臭水体修复效果的影响。研究表明,投加土著微生物功能菌并结合底泥曝气能够明显改善上覆水水质,加快底泥的修复。使用间歇曝气协同土著微生物功能菌作用时效果和连续曝气相近,且可降低运行成本。实验15 d后,上覆水COD、NH_3-N和TP去除率分别达67.6%、71.6%和92.2%,底泥有机质的降解速率提高了30%,底泥微生物活性增加5倍。     

过氧化钙缓释材料对河道水固磷及底泥控磷的机理研究

用聚乙二醇2000(PEG2000)和硬脂酸(SA)包埋粉末过氧化钙(CP)成功制备了CP缓释材料CP@PEG2000-SA。比较了粉末CP和CP@PEG2000-SA对上覆水中溶解性总磷的影响和对底泥中磷酸铝盐(Al-P)、磷酸铁盐(Fe-P)和磷酸钙盐(Ca-P)的影响。结果表明,CP@PEG2000-SA投加量宜为1.8kg/m2,在CP用量相同的条件下计算得到粉末CP投加量为1.0kg/m~2。投加粉末CP在10d内上覆水中溶解性总磷浓度迅速降至最低后又上升,而投加CP@PEG2000-SA可以实现35d内溶解性总磷持续缓慢下降。上覆水中的内源性磷一般来自底泥中Fe-P的释放。投加粉末CP虽能固定Fe-P含量,但起不到长效作用,甚至可能导致Al-P的释放。投加CP@PEG2000-SA可控制氧气释放速率,稳定pH,使得上覆水中溶解性总磷向底泥中的Al-P、Ca-P和Fe-P转化,起到长效抑制底泥中内源性磷向水体释放并同时吸收水体中磷的双重效应,达到了控磷目的。     

底泥煤渣帽封与药剂投加联用原位稳定化技术对上覆水体及底泥pH-Eh-COD的影响

将底泥有机物原地稳定化处理技术中药剂投加法和帽封法结合，研究以煤渣为帽封材料，苏州河底泥中分别投加零价铁（Fe⁰）及硝酸钙的实验里各体系上覆水体及底泥的pH、氧化还原电位（Eh）、有机含量在60 d的变化情况。结果表明，煤渣帽封下，底泥中投加Fe⁰或硝酸钙后上覆水体pH均在8左右，Eh呈下降趋势，投加Fe⁰后对上覆水体COD的影响较硝酸钙小，但均不会对上覆水体水质产生持久、较大的影响。从底泥有机质的去除率上来看，Fe⁰-煤渣帽封体系在反应周期里有机质的去除率约55%，而硝酸钙-煤渣帽封体系底泥有机质的去除率在27%左右。以Fe⁰-煤渣帽封材料复合体系运用在底泥原地稳定化帽封技术中降解有机物更为合适。     

红枫湖底泥磷负荷释放

为了研究高原湖泊底泥沉积物中磷的释放负荷,对贵州红枫湖区10个地区的沉积物进行了磷形态分析。选取10个采样点中5个典型区域,研究结果表明,底泥中各形态磷占总磷比例Org-P为58.6%,NaOH-P为29.91%,Ca-P为11.48%,底泥中主要的磷形态为有机磷。上覆水溶解性总磷酸盐(TSP)与底泥中各形态磷的相关性研究表明,底泥中的Ca-P与上覆水中的TSP几乎没有相关性,NaOH-P与Org-P与上覆水的TSP有较高的相关性(R2>0.94),而底泥中的总磷(TP)与上覆水中的TSP相关性最高(R2>0.98),底泥中这种形态的结构有利于抑制底泥的释放。研究表明,在10点位样品中,间隙水中TP和SRP(溶解性正磷酸)浓度远大于上覆水体中相应磷形态的浓度,间隙水中TP平均浓度为0.37 mg/L,SRP平均浓度为0.18 mg/L,上覆水体中TP平均浓度为0.10 mg/L,SRP平均浓度为0.02 mg/L,间隙水中TP、SRP与上覆水中TP、SRP存在了一种浓度梯度。     

曝气对生物促生剂修复城市黑臭河道水体的影响

在实验室条件下研究了曝气对生物促生剂修复城市黑臭河道水体效果的影响，并通过控制曝气时间及强度考察处理效果以确定曝气方式和曝气量。结果表明：在生物促生剂修复城市河道黑臭水体过程中使用曝气协同作用可大大增强生物促生剂的修复作用，加快修复速度。使用间歇曝气协同生物促生剂作用时效果与连续曝气相近，且可以降低运行成本。实验60d后，上覆水COD、NH3-N和TP去除率分别达46．8％、98．7％和73．3％，上覆水pH由7．61提高至7．92；底泥削减达5．49cm，底泥有机质削减率达10．5％。     

新型复合药剂原位修复河道底泥污染

采用新型复合药剂开展河道底泥原位修复技术研究,通过考察河道水质改善效果、底泥中磷含量及形态的变化确定药剂的最佳投加量。结果表明,投加复合药剂对上覆水体中TN、NH+4-N和TP均有不同程度的净化效果,且净化效果随药剂量的增加而增强,最高去除率分别达到23.52%、21.79%和81.5%,上覆水体COD去除率随药剂投加量增多呈先升后降的趋势,最高(投加量为600 mg·L~(-1))达到57.6%。从底泥磷含量及形态变化来看,投加药剂增大了底泥TP含量并促进底泥不稳态磷向稳定态磷转化。因此,从经济成本和修复效果方面综合分析,以投加量为600 mg·L~(-1)对底泥污染原位修复较为合适。     

溶解氧对底泥扰动状态下水体中磷去除和固定的影响

以太湖梅梁湾底泥和上覆水为研究对象，通过实验室实验研究了底泥扰动状态下溶解氧水平（2～4mg／L、5～6mg／L、7～8mg／L）对上覆水中磷去除和固定的影响。结果表明，底泥扰动和溶解氧水平对上覆水中磷迁移有明显影响。扰动时间延长，溶解性磷酸盐（DIP）和溶解性总磷（DTP）均呈降低的趋势；但溶解氧水平提高，上覆水中DIP和DTP浓度有所增加。底泥扰动和溶解氧水平改变了悬浮物上不同形态磷的数量分布。随着溶解氧水平提高，NH4Cl-P（1～5d平均值）和Fe／Al—P（1～5d平均值）含量及其占总磷（Tot—P）的百分比均呈逐渐降低的趋势。另外，闭蓄态铁铝结合态磷（Fe／Al—P）占Fe／Al—P的比值从51．2％（2～4mg／L）增加至54．1％（7～8mg／L）。     

好氧-富氧曝气生物处理在黑臭河涌原位修复中的应用

近年来,反复强调治理黑臭河涌的必要性,为了修复广东南海某黑臭河涌,采用优势菌接种和多级好氧-富氧生物处理原位修复集成工艺系统修复黑臭水体。实验结果表明,通过向底泥和上覆水体里投加培养、驯化的优势菌种,辅以光合细菌、硝化细菌,上覆水体的水质显著好转,水体透明度由初始的5 cm左右,上升至35 cm左右,水体黑臭完全消除。在土著微生物的作用下,水体中的有机物得到很好的去除,上覆水体的COD、氨氮、BOD_5和总磷的浓度显著下降,其去除率分别达到68.1%~78.7%、79.8%~80.1%、84.8%~85.2%和76.4%~83.6%,河涌的自净能力得到大大提高。     

曝气对黑臭河道污染物释放的影响

利用黑臭河道模拟装置,对比研究了在静置和人工曝气2种方式下底泥污染释放特征及对上覆水水质的影响。结果表明,与静置释放相比,人工曝气促使实验前期底泥污染物快速释放,使得上覆水体中的各项污染物指标上升;随着水体中DO浓度的增加,硝化细菌、嗜磷菌等好氧细菌的活性增强,水体中的COD、氨氮、TN和TP得到降解或转化,浓度快速下降。实验期内,人工曝气底泥中TN、TP的平均释放速率分别为:-0.11 g/(m2·d)和-0.02 g/(m2·d),并且TP由最初的0.96 mg/L降到最终的0.48 mg/L,去除率达到50.00%。人工曝气在前期对水体中各污染指标有升高的影响,但增加了水体中的DO浓度,可以有效地抑制底泥中氮和磷的释放,对水体有机污染物、TN及TP有一定的削减作用,因此,该技术适合黑臭河道的水体修复。     

直接投菌法在城市重污染河流治理中的应用研究

在无截污和清除内源的情况下,对深圳市甘坑河采用梅花式接种法将本源微生物菌剂分两次直接接入河流水体及底泥中。结果表明,第1次接种后的4 d内各项水质指标都不稳定,4 d后,悬浮物、COD、TP和NH3-N等浓度下降,水质明显改善;但从第8天开始,COD、NH3-N和TP的去除率同时下降,本源微生物的处理效率开始降低,需进行第2次接种;第2次接种后,DO浓度提升至2.0 mg/L以上,COD、TP和NH3-N的去除率分别保持在40%、30%和40%以上。结果表明,直接投菌法在城市重污染河道治理中可以初步消除河道的黑臭现象,修复水质。     

Influence of algal bloom degradation on nutrient release at the sediment–water interface in Lake Taihu, China

Algal bloom could drastically influence the nutrient cycling in lakes. To understand how the internal nutrient release responds to algal bloom decay, water and sediment columns were sampled at 22 sites from four distinct regions of China’s eutrophic Lake Taihu and incubated in the laboratory to examine the influence of massive algal bloom decay on nutrient release from sediment. The column experiment involved three treatments: (1) water and sediment (WS); (2) water and algal bloom (WA); and (3) water, sediment, and algal bloom (WSA). Concentrations of dissolved oxygen (DO), total nitrogen (TN), total phosphorus (TP), ammonium (NH ₄ ⁺ -N), and orthophosphate (PO ₄ ^3? -P) were recorded during incubation. The decay of algal material caused a more rapid decrease in DO than in the algae-free controls and led to significant increases in NH ₄ ⁺ -N and PO ₄ ^3? -P in the water. The presence of algae during the incubation had a regionally variable effect on sediment nutrient profiles. In the absence of decaying algae (treatment WS), sediment nutrient concentrations decreased during the incubation. In the presence of blooms (WSA), sediments from the river mouth released P to the overlying water, while sediments from other regions absorbed surplus P from the water. This experiment showed that large-scale algal decay will dramatically affect nutrient cycling at the sediment–water interface and would potentially transfer the function of sediment as “container” or “supplier” in Taihu, although oxygen exchange with atmosphere in lake water was stronger than in columns. The magnitude of the effect depends on the physical–chemical character of the sediments.     

Effects of oxygen on the release and distribution of phosphorus in the sediments under the light condition

Effects of oxygen on the release and distribution of phosphorus (P) in the sediments in the presence of light were investigated, using sediment cores and overlying water from Lake Taihu, in China. The results show that P can be released from sediments to the overlying water in both anoxic and aerobic conditions. But more P was released in the anoxic condition. The transformation of P between various fractions in the sediments was observed during the release experiments. Concentrations of Ca-bound P and organic P in the sediments decreased in both conditions, but Fe/Al-bound P increased in the aerobic condition. The decrease of total P and P fractions in the sediments is consistent with the accumulative increase in quantity (AIQ) of total P (TP) in the overlying water, but is contrary with the AIQ of dissolved inorganic P. This is due to the uptake of algae by the dissolved inorganic P. Total nitrogen in the sediments in the anoxic condition was lower than that in the aerobic condition, and pH in the overlying water increased in the anoxic condition.     

不同水温时底泥扰动对不同形态磷分布的影响

研究了江南地区典型水温条件下,底泥扰动对上覆水中不同形态磷迁移的影响.结果表明,不同水温条件下,底泥扰动均有利于上覆水中溶解态磷(即溶解性总磷酸盐(DTP),包括溶解性正磷酸盐(DIP)和溶解性有机磷(DOP))向底泥迁移.与对照试验相比,不同水温时的扰动均导致DIP/TP和DTP/TP明显降低.与初始状态(第0天时)相比,扰动导致DIP/TP分别降低了39.61百分点(冬季水温)和17.38百分点(夏季水温),而DTP/TP则分别降低了39.16百分点(冬季水温)和19.06百分点(夏季水温).相反,对照试验中,DTP/TP分别上升了24.90百分点(冬季水温)和23.37百分点(夏季水温).这说明底泥扰动促进了溶解态磷向颗粒态磷(PP)的转化.     

Enhancement of dissolved phosphorus release from sediment to lake water by Microcystis blooms--an enclosure experiment in a hyper-eutrophic,subtropical Chinese lake

To clarify the possible influence of Microcystis blooms on the exchange of phosphorus (P) between sediment and lake water, an enclosure experiment was conducted in the hypereutrophic subtropical Lake Donghu during July-September 2000. Eight enclosures were used: six received sediment while two were sediment-free. In mid-August, Microcystis blooms developed in all the enclosures. There was a persistent coincidence between the occurrence of Microcystis blooms and the increase of both total P (TP) and soluble reactive P (SRP) concentrations in the water of the enclosures with sediments. In sediment-free enclosures, TP and SRP concentrations remained rather stable throughout the experiment, in spite of the appearance of Microcystis blooms. The results indicate that Microcystis blooms induced massive release of P from the sediment, perhaps mediated by high pH caused by intense algal photosynthesis, and/or depressed concentrations of nitrate nitrogen (NO3-N).     

Characteristics of phosphorus components in surface sediments from a Chinese shallow eutrophic lake (Lake Taihu): new insights from chemical extraction and <Superscript>31</Superscript>P NMR spectroscopy

As a primary factor responsible for lake eutrophication, a deeper understanding of the phosphorus (P) composition and its turnover in sediment is urgently needed. In this study, P species in surface sediments from a Chinese large eutrophic lake (Lake Taihu) were characterized by traditional fractionation and ³¹P nuclear magnetic resonance (NMR) spectroscopy, and their contributions to the overlying water were also discussed. Fractionation results show that NaOH-P predominated in the algal-dominated zone, accounting for 60.1% to total P in Zhushan Bay. Whereas, refractory fractions including HCl-P and residual-P were the main P burial phases in the macrophyte-dominated zone, the center and lakeshore. Recovery rates of the total P and organic P were greatly improved by using a modified single-step extraction of NaOH-EDTA, ranging from 22.6 to 66.1% and from 15.0 to 54.0%. Ortho-P, monoester-P, and pyro-P are identified as the major P components in the NaOH-EDTA extracts by ³¹P NMR analysis. Trace amount of DNA-P appeared only in sediments from algal- and macrophyte-dominated zones, ascribing to its biological origin. The relative content of ortho-P is the highest in the algal-dominated zone, while the biogenic P including ester-P and pyro-P is the highest in the macrophyte-dominated zone. Moreover, ortho-P and pyro-P correlated positively with TP and chlorophyll a in the overlying water, whereas only significant relationships were found between monoester-P, biogenic P, and chlorophyll a. These discrepancies imply that inorganic P, mainly ortho-P, plays a vital role in sustaining the trophic level of water body and algal bloom, while biogenic P makes a minor contribution to phytoplankton growth. This conclusion was supported by the results of high proportion of biogenic P in algae, aquatic macrophytes, and suspended particulate from the published literature. This study has significant implication for better understanding of the biogeochemical cycling of endogenous P and its role in affecting lake eutrophication.     

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     

复合人工湿地对高污染性河流营养物的去除

为了研究复合人工湿地对高污染性河流营养物的去除效果，在西安皂河人渭处建立了一座占地约13334m。包括5组不同复合人工湿地工艺的中试系统。经过1年的实验研究表明，复合型人工湿地对COD、BOD。和ss有很好的去除效果，其去除率最高分别为（82．4±7．2）％、（97．1±1．7）％和（94±2．7）％，对于脱氮除磷而言，以水力停留时间4．1d的复合湿地系列4的处理效果最佳，对TN、NH3-N和TP的年去除率达（79．4±14）％、（79．2±13．7）％和（82．3±12）％。氮的去除效果受温度季节性变化影响较大，夏季平均水温高于19℃有更好的处理效果，磷的去除效果受温度影响不大；NO2-、NO3-去除率呈现负增长，在湿地尾端出现了不同程度的积累。