沈阳河流和沿岸地区环境多介质中锰的分布及生态风险评价

对沈阳地区主要河流河水、沉积物及周边地下水、土壤、农作物和人发样品中锰浓度进行了分析,并对其分布特征和生态风险进行了探讨。沈阳河流沿岸地区表层土壤样品中锰浓度平均值处于辽河平原土壤中锰元素背景值范围之内并低于地壳丰度。生活饮用水水源地的水锰浓度(0.01mg·L-1)符合我国集中式生活饮用水地表水源地标准。浑河、细河、沈抚灌渠水中锰浓度为0.06～14.2mg·L-1,与国内外其他河流相比没有明显锰污染;但细河流域部分地区地下水中锰浓度(夏、秋季分别平均为4.17和2.75mg·L-1)超过国家地下水质量标准规定III和IV类水。沈阳彰驿地区农作物中锰浓度范围为3～266μg·g-1干重,不同作物锰浓度差异较大;锰污染较严重的农作物为浅层地下水灌溉所致。当地居民通过饮用水和食用农作物途径的锰摄入量几乎相当,均低于最小中毒剂量0.06mg·kg-1体重·d-1。细河附近一些村庄居民头发中的锰浓度平均达24.6μg·g-1,其中女性平均为26.4μg·g-1,高于男性,接近国内正常发锰(1.3～9.8μg·g-1)上限的3倍;发锰浓度与居民年龄存在着明显关系,20～30岁年龄段人群发锰较高。     

石油烃降解物对Cd在土壤－植物系统中迁移转化影响的研究

研究棕榈酸、儿茶酚和香草酸对土壤中Ｃｄ行为的影响表明,土壤中儿茶酚对水稻的毒害浓度为１００ｍｇ·ｋｇ－１,而香草酸则为５００ｍｇ·ｋｇ－１．当土壤中儿茶酚为５０００ｍｇ·ｋｇ－１时,水稻籽实中Ｃｄ浓度降到０．００８ｍｇ·ｋｇ－１,土壤淋溶液中Ｃｄ浓度降为０．００５ｍｇ·Ｌ－１,３种有机物均能增加土壤中有机结合态Ｃｄ的比例,５０００ｍｇ·ｋｇ－１的儿茶酚处理,土壤中有机质结合态Ｃｄ占总Ｃｄ的４８．７１％．     

变饱和带条件下污水灌溉对土壤氮素运移和冬小麦生长的影响

为了研究地下水浅埋区污水灌溉对土壤环境及作物生长的影响,设置地下水埋深(2、3m和4m)和灌水水量(900m3·hm-2和1200m3·hm-2)2个因素,对冬小麦全生育期土壤氮素和冬小麦生长发育指标进行试验,试验在地中渗透仪中进行.结果显示:灌水后,不同处理土壤中硝态氮含量均显著增加,灌水水平越高,土壤中硝态氮含量增加越多;灌水后,灌水水平B1(900 m3·hm-2)不同潜水埋深地下水硝态氮分别增加34.67%、24.94%、20.88%;灌水水平B2(1200 m3·hm-2)不同潜水埋深地下水硝态氮分别增加58.42%、38.98%、27.21%.潜水埋深越浅,地下水中硝态氮的浓度增加越大,这也就表明由于淋溶和硝化作用产生的硝态氮造成浅层地下水污染的风险越大.污水灌溉对冬小麦的生长发育指标和产量有促进作用;相同灌水水平(B1 和B2),地下水埋深影响冬小麦生长发育指标的大小顺序为:2m＞3m＞4m.     

一株高效脱酚菌芽糖假丝酵母10—4的研究

从炼油厂严重污染的污水和土壤中分离筛选到１２株假丝酵母及丝孢酵母,能以苯酚为唯一碳源生长,２８－４０ｈ内降解苯酚可达１２００ｍｇ／Ｌ以上。其中１０－４号菌株降解苯酚浓度最高可达１７００ｍｇ／Ｌ。在含５００ｍｇ／Ｌ苯酚及２０ｍｇ／ＬＣＮ＾－培养液中,降解苯酚的同时能降解１３．７ｍｇ／Ｌ的ＣＮ＾－。     

利用转基因植物降解土壤中的残留炸药

《ＮａｔｕｒｅＢｉｏｔｅｃｈｎｏｌｏｇｙ》１９９９年１７卷５期４９１～４９４页报道：土壤和地下水的持续污染已引起公众日益迫切的关注。已知阴沟肠杆菌ＰＢ２分离株可利用硝酸酯炸药诸如季戊四醇四硝酸酯或季戊炸药（ＰＥＴＮ）和三硝酸甘油酯或硝化甘油（ＧＴＮ）,作为其生长的唯一氮源（Ｂｉｎｋｓ等,１９９６）。依赖于烟酰胺腺嘌呤二核苷酸磷酸（ＮＡＤＰＨ）的ＰＥＴＮ还原酶可影响脱硝作用（Ｆｒｅｎｃｈ等,１９９６）。ＰＥＴＮ还原酶可通过还原途径导致氮的释放,从而使战争地区土壤中的重要而持久的污染物———芳香类炸…     

多年模拟氮沉降对华西雨屏区苦竹人工林土壤节肢动物的影响

土壤动物在生态系统养分循环中扮演着重要角色,其中土壤节肢动物在凋落物破碎和土壤团聚体形成中起着决定性作用。为探究多年模拟氮沉降对苦竹人工林土壤节肢动物的影响,于2007年11月起在华西雨屏区苦竹人工林进行了每月1次的模拟氮沉降试验,以硝酸铵为氮源,设对照(0 g N·m~(-2)·a~(-1))、低氮(5 g N·m~(-2)·a~(-1))、中氮(15 g N·m~(-2)·a~(-1))和高氮(30 g N·m~(-2)·a~(-1)) 4个处理。在施氮6.5年后分别于2014年1月、10月,2015年1月采集凋落物层和0～15 cm土层样品带回实验室分离鉴定。结果显示:本试验共观察到土壤节肢动物1852只,隶属于3门7纲18目;凋落物层土壤节肢动物个体数和类群数随施氮浓度的升高而增加,且高氮处理显著高于对照;土壤层土壤节肢动物个体数和类群数随施氮浓度的升高而减少,但与对照相比均不显著;模拟氮沉降对凋落物层和土壤层土壤节肢动物多样性指数、均匀度指数和丰富度指数均无显著影响。     

城市污水厂污泥改良水蚀沙土对地下水风险模拟

为探究城市污水厂污泥改良水蚀沙土后对地下水的环境风险,检验污水厂污泥作为土壤改良剂改良水蚀沙土的可行性,试验基于污水厂离心脱水污泥对沙土的改良效果,模拟水蚀沙土土层后,利用污泥掺混量为15%的改良水蚀沙土作为0~20 cm土层土壤,通过饱和淋洗的方式分析渗出液水质水量,评价利用掺混城市污水厂污泥的改良水蚀沙土直接作为表层土壤后对地下水的环境风险。结果表明:氮素对地下水的风险较大,且存在较大的持续性风险,TN中硝态氮含量占比较高,硝态氮与TN含量显著相关(r=0.997,P0.01);深层土壤会发生亚硝化反应,极大地增加地下水亚硝态氮污染风险;渗出液TP峰值为0.18 mg·L~(-1),约是空白淋出液的2.6倍,淋出液COD与亚硝态氮和TP均显著相关(r=0.630,P0.05;r=0.677,P0.05),COD所代表的碳源成为改良水蚀沙土地下水亚硝态氮和TP风险的主要限制因素;而污泥的水解酸化在降低渗出液pH的同时,增加了渗出液的COD含量,进而增加地下水风险,试验COD峰值含量为46 mg·L~(-1),约是空白淋出液的2.5倍,pH与COD显著相关(r=-0.760,P0.01);重金属对地下水风险在试验后期较高,呈现一定的后效性;含泥量为15%的改良沙土在过饱和淋洗过程中会对地下水产生一定的环境风险,表明掺混城市污水厂污泥的改良水蚀沙土在一定条件下可能会对地下水产生影响,需要采取一定污染防控措施来控制风险。     

紫松果菊对多环芳烃重污染土壤修复效能

采用盆栽试验,以实际油田污染土与自然土和沙土按照一定比例配置两种污染浓度的土壤(PAHs总浓度分别为122.40和183.60 mg·kg-1),以株高、生物量变化以及芘(Pyr)、屈(CHR)、苯并b荧蒽(Bb F)、苯并k荧蒽(Bk F)4种多环芳烃去除率为指标,研究了紫松果菊对PAHs污染土壤的修复效能。结果表明:(1)4种多环芳烃污染土壤对紫松果菊株高和生物量有明显抑制作用,在PAHs总浓度为183.60 mg·kg-1时,紫松果菊仍能存活,说明紫松果菊对PAHs污染土壤具有较强的耐性。(2)在PAHs总浓度为183.60mg·kg-1时,紫松果菊对土壤中4种PAHs的去除率分别为66.2%、70.3%、40.6%和65.4%,4种PAHs的总量由183.60 mg·kg-1降到104.52 mg·kg-1,总去除率为56.93%,远大于对照组中PAHs总去除率。说明紫松果菊具有修复PAHs重污染土壤的潜能。相关性分析发现,PAHs的去除率与地下生物量的相关性更好,说明植物地下生物量对多环芳烃去除率影响较大。本研究拓展了利用植物修复PAHs污染土壤的应用范围,使重污染土壤的植物修复成为可能。     

细河河水及其沿岸地下水水质的有机污染特征

调查了沈阳市细河河水及其沿岸地下水水质中石油类和美国环保局(USEPA)"黑名单"上的16种优先控制多环芳烃(PAHs)的有机污染现状,评价细河污染带来的生态风险。结果表明:细河河水中石油类浓度和16种PAHs总浓度范围分别为0.031～1.819mg.L-1和0.026～0.384μg.L-1,平均浓度分别为1.007mg.L-1和0.151μg.L-1;细河沿岸地下水中石油类浓度和16种PAHs总浓度范围分别为0.020～0.987mg.L-1和0.051～0.389μg.L-1,平均浓度分别为0.364mg.L-1和0.133μg.L-1;细河河水和地下水中的石油类污染严重;河水中的PAHs浓度在流经规模较大的城镇或乡镇处出现高值点,苯并(b)荧蒽和苯并(k)荧蒽在河水与地下水中的检出率较高,对水生生态系统健康构成了潜在的威胁。     

氮沉降对毛竹非结构性碳组成与分配的影响

植物组织中非结构性碳水化合物(non-structural carbohydrate,NSC)的浓度反映了植物整体的碳供应状况,但其对氮沉降的响应人们仍知之甚少。毛竹是我国分布最广、产值最大的禾本科竹类植物,在亚热带地区生态环境建设和山区经济发展中发挥着重要作用。本文以粗放经营的毛竹林为研究对象,设计4个模拟氮沉降处理水平:低氮(L,30kg·hm~(-2)·a~(-1))、中氮(M,60 kg·hm~(-2)·a~(-1))、高氮(H,90 kg·hm~(-2)·a~(-1))和对照(CK,0kg·hm~(-2)·a~(-1)),处理时间32个月。结果表明:(1)毛竹中可溶性糖是NSC的主要组分;(2)毛竹中NSC浓度表现为秆(4.1%)叶(3.6%)枝(3.3%);(3)4龄竹竹叶的NSC浓度显著低于2龄竹(P0.05),竹龄对竹秆NSC浓度的影响显著(P0.05),对竹枝NSC浓度的影响不显著(P0.05);(4)氮沉降对毛竹竹枝和竹秆的NSC浓度影响显著(P0.05),竹枝的NSC浓度随着氮沉降量的增加呈现先上升后下降的趋势,竹秆的NSC浓度随着氮沉降量的增加呈现先下降后上升的趋势,对竹叶的NSC浓度影响不显著(P0.05);(5)氮沉降和竹龄的交互作用对毛竹竹叶、竹枝和竹秆的NSC浓度均有显著影响(P0.05)。适当的氮沉降会促进该区域粗放经营毛竹林的生长,利于积累更多的生物量碳。     

Nitrogen removal from polluted river by enhanced floating bed grown canna

Floating beds of canna can remove nitrogen from polluted river water, but the removal efficiency is not very high in a short time, so some enhanced methods must be used to improve nitrogen removal efficiency by the system. Immobilized denitrifying bacteria and aeration were added into the canna floating bed. The experimental results showed that these enhancements substantially improved the nitrogen removal efficiency of the floating beds. With the enhancements, total nitrogen removal was 72.1%, ammonia nitrogen oxidation was 100%, nitrate nitrogen removal was 75.8%, nitrite nitrogen removal was 95.9%, and COD removal was 94.6% in 5 days. Without the enhancements, the canna floating bed system removed only 50.4% of the total nitrogen, 22.4% of the nitrate nitrogen, 5.3% of the nitrite nitrogen and 39.9% of the COD, respectively, in 5 days, but did accomplish 100% oxidation of the ammonia nitrogen. The experimental results provide an improved method for the treatment of polluted river water.     

Dissolved nitrogen in drinking water resources in Al-Mahareth village of Assir – Saudi Arabia

A water quality study was carried out on ground water wells, which serve as drinking water sources in farming communities in Al-Mahareth village of Assir region of the Kingdom of Saudi Arabia. The objective of this research was to determine concentrations of different forms of nitrogen in drinking water samples. Water samples were collected from these sources every 3 months (from January to December 2008) and analyzed for ammonia, nitrate and nitrite using the Plaintest Photometer Method. Results indicated that the annual mean concentration of nitrate, nitrite and ammonia varied from 23.09 to 25.06 mg/l, 0.006 to 0.36 mg/l and 0.008 to 0.179 mg/l, respectively. An important observation was that, in general, higher nitrate and nitrite concentrations were found during the rainy season compared to the dry season. Concentrations of these potentially toxic substances were below WHO acceptable limits for surface and ground waters, indicating that these water resources appear safe for drinking from a dissolved nitrogen perspective.     

Improvement of NaNO2-oxidizing activity in Nitrobacter vulgaris by coentrapment in polyacrylamide containing polydimethylsiloxane copolymer and DEAE-sephadex

Removal of nitrite and nitrate from drinking water has attracted great attention in recent years because of the human health risk induced by the exposure to contaminated groundwater and surface water. We have therefore tested a model nitrite oxidation system by coentrapping the NaNO2 oxidizer Nitrobacter vulgaris with polydimethylsiloxane (PDMS) copolymer and DEAE-Sephadex in a polyacrylamide gel. The copolymer and the anion exchanger facilitate the diffusion of oxygen and NaNO2, respectively, into the gel matrix. To test the nitrite-oxidizing activity, the entrapped cells were coupled to a thermal sensor. Coentrapment of 5% (wt/vol) DEAE-Sephadex with Nitrobacter vulgaris increased the nitrite-oxidizing activity by a factor of 3.7 compared to entrapped cells alone, and by the addition of 0.86% (wt/vol) artificial oxygen carrier PDMS copolymer increased the activity further to 4.3 times higher. Operational and storage stability of the coentrapped N.vulgaris also improved. This suggests that this enhanced immobilized cell system can also be used for nitrite oxidation to nitrate in drinking water as an on-line thermally monitored bioreactor.     

Urinary nitrate excretion in relation to murine macrophage activation. Influence of dietary L-arginine and oral NG-monomethyl-L-arginine

Murine macrophage oxidation of L-arginine guanidino nitrogen to nitrite/nitrate yields an intermediate effector, possibly nitric oxide, with antimicrobial activity. Total body nitrogen oxidation metabolism (NOM) was measured in vivo by determining the urinary nitrate excretion of mice ingesting a chemically defined nitrite/nitrate-free diet. As reported previously, mycobacterial infection with bacillus Calmétte-Guerin led to a large increase in urinary nitrate excretion. This increase was temporally related to macrophage activation in vivo. The substrate for macrophage nitrogen oxidation metabolism in vitro, L-arginine, was deleted from the diet without ameliorating the urinary nitrate excretion response induced by BCG. This suggested that L-arginine was synthesized endogenously because there are no other known natural substrates for NOM. A competitive inhibitor of NOM, the L-arginine analog, NG-monomethyl-L-arginine was fed to mice in their drinking water. NG-monomethyl-L-arginine ingestion blocked both basal and bacillus Calmétte-Guerin-induced urinary nitrate excretion over a 2-4 week time span. These experimental conditions should prove useful for further investigation on the role of macrophage NOM in host defense against intracellular microorganisms.     

浑河河水及其沿岸地下水污染特征

选择沈阳地区重要河流浑河及其沿岸地下水进行定量分析,研究并探讨了包括无机物和有机物在内的水质综合污染特征。结果表明,浑河河水中氨氮、硝氮、亚硝氮和酚超过了地表水环境质量标准,最大超标倍数分别为15.8、1.5、82.4和1.8倍,检测出的11种卤代烃、氯苯和六六六等有机物均未超标。浑河沿岸地下水中氨氮、硝氮、亚硝氮、化学需氧量、酚和铅超过地下水质量标准,超标率分别为31.6%、10.5%、26.3%、36.8%、47.4%和26.8%,检测出的4种卤代烃和六六六等有机物均未超标。河水及其沿岸地下水中的污染物,尤其是有机污染物种类和浓度高值基本出现在城西的谟家—大祝断面之间。浑河水质主要受城市工业废水、居民生活污水排放的影响,沿岸地下水的污染来源包括工业生产或农村居民生活造成的地表污染物垂直入渗式的点源污染、浑河水侧向渗透补给式的线源污染以及农药化肥使用产生的面源污染,而有机污染物主要通过点源污染地下水。浑河各区段的使用功能、包气带岩性及沿岸水源地开采井布局等因素都为受污染的河水对沿岸几百米范围内的浅层地下水的补给提供了条件,造成浅层地下水的污染,对当地生态系统及人类健康构成潜在威胁。     

Anaerobic Benzene Biodegradation Linked to Nitrate Reduction

Benzene oxidation to carbon dioxide linked to nitrate reduction was observed in enrichment cultures developed from soil and groundwater microcosms. Benzene biodegradation occurred concurrently with nitrate reduction at a constant ratio of 10 mol of nitrate consumed per mol of benzene degraded. Benzene biodegradation linked to nitrate reduction was associated with cell growth; however, the yield, 8.8 g (dry weight) of cells per mol of benzene, was less than 15% of the predicted yield for benzene biodegradation linked to nitrate reduction. In experiments performed with [¹⁴C]benzene, approximately 92 to 95% of the label was recovered in ¹⁴CO₂, while the remaining 5 to 8% was incorporated into the nonvolatile fraction (presumably biomass), which is consistent with the low measured yield. In benzene-degrading cultures, nitrite accumulated stoichiometrically as nitrate was reduced and then was slowly reduced to nitrogen gas. When nitrate was depleted and only nitrite remained, the rate of benzene degradation decreased to almost zero. Based on electron balances, benzene biodegradation appears to be coupled more tightly to nitrate reduction to nitrite than to further reduction of nitrite to nitrogen gas.     

Mechanism of charged pollutants removal in an ion exchange membrane bioreactor: drinking water denitrification

The mechanism of anionic pollutant removal in an ion exchange membrane bioreactor (IEMB) was studied for drinking water denitrification. This hybrid process combines continuous ion exchange transport (Donnan dialysis) of nitrate and its simultaneous bioreduction to gaseous nitrogen. A nonporous mono-anion permselective membrane precludes direct contact between the polluted water and the denitrifying culture and prevents secondary pollution of the treated water with dissolved nutrients and metabolic products. Complete denitrification may be achieved without accumulation of NO3(-) and NO2(-) ions in the biocompartment. Focus was given to the effect of the concentration of co-ions, counterions, and ethanol on the IEMB performance. The nitrate overall mass transfer coefficient in this hybrid process was found to be 2.8 times higher compared to that in a pure Donnan dialysis process without denitrification. Furthermore, by adjusting the ratio of co-ions between the biocompartment and the polluted water compartment, the magnitude and direction of each individual anion flux can be easily regulated, allowing for flexible process operation and control. Synthetic groundwater containing 135-350 mg NO3(-) L(-1) was treated in the IEMB system. A surface denitrification rate of 33 g NO3(-) per square meter of membrane per day was obtained at a nitrate loading rate of 360 g NO3(-) m(-3)d(-1), resulting in a nitrate removal efficiency of 85%.     

Ion exchange membrane bioreactor for selective removal of nitrate from drinking water: control of ion fluxes and process performance

An ion exchange membrane bioreactor (IEMB), consisting of a monoanion permselective membrane dialyzer coupled to a stirred anoxic vessel with an enriched mixed denitrifying culture, has been studied for nitrate removal from drinking water. The influence of nitrate and chloride concentrations on the selectivity of nitrate transport in the IEMB process was investigated. With appropriate dosing of chloride ions to the IEMB biocompartment, it was possible to regulate the net bicarbonate flux in the system, thus maintaining the bicarbonate concentration in the treated water at the desired level. The latter was not possible to achieve in Donnan dialysis, operated as a single process in which, besides the lower nitrate removal efficiency found, bicarbonate was co-extracted together with nitrate from the polluted water stream. Residual carbon source (ethanol) and nitrite were not detected in the treated water produced in the IEMB system. With a concentration of nitrate in the polluted water three times higher than the maximum contaminant level of 50 mg L(-1) allowed, the IEMB process was successfully operated for a period of 1 month before exceeding this limit.     

Dietary nitrate increases gastric mucosal blood flow and mucosal defense

Salivary nitrate from dietary or endogenous sources is reduced to nitrite by oral bacteria. In the acidic stomach, nitrite is further reduced to bioactive nitrogen oxides, including nitric oxide (NO). In this study, we investigated the gastroprotective role of nitrate intake and of luminally applied nitrite against provocation with diclofenac and taurocholate. Mucosal permeability ((51)Cr-EDTA clearance) and gastric mucosal blood flow (laser-Doppler flowmetry) were measured in anesthetized rats, either pretreated with nitrate in the drinking water or given acidified nitrite luminally. Diclofenac was given intravenously and taurocholate luminally to challenge the gastric mucosa. Luminal NO content and nitrite content in the gastric mucus were determined by chemiluminescence. The effect of luminal administration of acidified nitrite on the mucosal blood flow was also investigated in endothelial nitric oxide synthase-deficient mice. Rats pretreated with nitrate or given nitrite luminally had higher gastric mucosal blood flow than controls. Permeability increased more during the provocation in the controls than in the nitrate- and nitrite-treated animals. Dietary nitrate increased luminal NO levels 50 times compared with controls. Nitrate intake also resulted in nitrite accumulation in the loosely adherent mucous layer; after removal of this mucous layer, blood flow was reduced. Nitrite administrated luminally in endothelial nitric oxide synthase-deficient mice increased mucosal blood flow. We conclude that dietary nitrate and direct luminal application of acidified nitrite decrease diclofenac- and taurocholate-induced mucosal damage. The gastroprotective effect likely involves a higher mucosal blood flow caused by nonenzymatic NO production. These data suggest an important physiological role of nitrate in the diet.     

Health-risk assessment related to the fluoride,nitrate, and nitrite in the drinking water in the Sanandaj,Kurdistan County,Iran

The concentration of fluoride and nitrate in groundwater is usually higher than that of surface water. The main objective of this study was to estimate the health-risk assessment associated with fluoride, nitrate, and nitrite in drinking water in Sanandaj and its villages. The number of samples in the Sanandaj and its rural was 106. The average concentration of fluoride in urban and rural drinking water was 0.22 mg/l and 0.27 mg/l, respectively. Fluoride concentration was also close to urban and rural drinking water. The concentration of nitrate in urban and rural drinking water was in the range between 0.28–27.77 mg/l and 1.28–80 mg/l, respectively. The concentration of nitrate reported in rural samples was higher than that of urban samples. The maximum concentration of nitrate reported in this study was 80 mg/l. The mean CDI for nitrate in the men, women, and children was 0.4258, 0.5110, and 1.1454, respectively. The findings of this study indicated that all three groups studied were exposed to nitrate contact hazards (HQ > 1). Therefore, the HQ in each of the three groups was higher than 1, which should be carefully monitored and necessary measures should be performed.