栽培水分对采摘后油菜硝酸盐与亚硝酸盐含量的影响

采用盆栽方法栽培油菜(Brassicaca mpestrisL.),研究了灌水水平对采摘后油菜植株体硝酸盐与亚硝酸盐含量随时间变化的影响。共设高(灌水控制上限为田间持水量)、中(灌水控制上限为田间持水量的75%)和低(灌水控制上限为田间持水量的50%)3个灌水水平。油菜采摘后恒温贮存,定期测定油菜植株体内硝酸盐、亚硝酸盐含量。研究结果表明:不同灌水水平和贮存时间以及两者的交互作用都能显著地影响油菜植株体硝酸盐和亚硝酸盐含量;在采摘后的8d时间里,低灌水水平处理(0.50θf处理)的油菜植株体硝酸盐含量一直高于其它两处理;采摘后当天测定高灌水水平处理(1.00θf处理)的油菜植株体硝酸盐含量最低,以后则以中等灌水水平处理(0.75θf处理)的油菜植株体硝酸盐含量为最低。采摘后当天测定油菜植株体亚硝酸盐含量,亦以高灌水水平处理(1.00θf处理)为最低。采摘后油菜植株体硝酸盐和亚硝酸盐含量都经历一个先降低、后升高、再降低的变化过程。因此,从对人体健康及卫生的角度出发,以较高灌水水平栽培油菜,采摘后在一两天内食用,有利于将其硝酸盐和亚硝酸含量控制在较低水平。     

广东省典型地区蔬菜硝酸盐与亚硝酸盐污染状况评价

研究了广东省西翼的湛江市、珠江三角洲地区的东莞市、惠州市、中山市、珠海市和佛山市顺德区等典型地区大型蔬菜生产基地中4种蔬菜148个样品中硝酸盐与亚硝酸盐的污染现状。采用国家标准(GB18406.1—2001)进行评价,在所检测的蔬菜样品中,有36.5%样品的硝酸盐含量超标,亚硝酸盐含量相对较低;以WHO/FAO规定的日允许摄入量换算得到的标准评价蔬菜的硝酸盐污染状况,污染程度严重的蔬菜样品占62.2%,中、重度污染的占16.9%,轻度污染的占20.9%。蔬菜中硝酸盐含量由高到低依次为叶菜类>瓜类>豆类>茄果类。因而有必要采取有效的污染防治措施控制该地区蔬菜中硝酸盐污染状况。     

珠江三角洲典型地区蔬菜硝酸盐与亚硝酸盐污染评价

研究了珠江三角洲典型地区中山市大型蔬菜生产基地中9种蔬菜30个样品中硝酸盐与亚硝酸盐的污染现状,初步摸清了蔬菜中硝酸盐及亚硝酸盐的污染状况。并以WHO/FAO规定的日允许摄入量换算得到的标准评价了其主要蔬菜品种的硝酸盐污染状况。结果表明:在被调查的蔬菜中,硝酸盐含量由高到低依次为菜心→白菜>芥菜→空心菜→生菜→瓜果类,菜心、芥菜和白菜为严重污染,生菜与空心菜为重污染,瓜果类蔬菜为轻污染;亚硝酸盐含量普遍较低,均未超标。因而有必要采取有效的污染防治措施控制该地区蔬菜中的硝酸盐污染状况。     

Measurement of residues of benomyl and mancozeb pesticides in shrub and nonshrub cucumbers sampled from different regions of Mazandaran province (Iran)

Farmers use mancozeb against cucumber pests, such as Perono spoxa, in large amounts without consideration of potential chronic human health hazards resulting from pesticide accumulation in food and fruits. Considering the necessity of food for humans and importance of fruit in daily diet, as well as the determination of pesticide residues in food and fruits as mandated by WHO and FAO, the residues benomyl and mancozeb, the most prominently used pesticides in Iran, were measured. In this study cucumbers from 76 sample regions were used. Data showed that the amounts of benomyl was related to the type of cucumber in the regions, but there was no significant relationship between the amount of mancozeb and type of cucumber.     

叶菜类蔬菜硝酸盐含量及其与土壤肥力因素的关系

对长沙市蔬菜生产基地春夏季节3种叶菜类蔬菜硝酸盐含量进行测定并与对应的菜园土壤8个肥力因素进行相关分析。结果表明,叶菜类蔬菜中,以小白菜硝酸盐含量最高,平均含量为3336±1359mg/kg,污染最严重;所调查的14个样本中超过四级标准达到严重污染水平的占64%以上。叶菜类蔬菜硝酸盐含量与土壤硝酸盐含量呈正相关,其中小白菜和苋菜相应的相关系数和通径分析系数均达5%以上显著水平。土壤硝酸盐含量是影响叶菜类蔬菜硝酸盐含量的主要土壤肥力因素。     

Nitrate/nitrite poisoning in dairy cattle associated with consumption of forages irrigated with municipally treated wastewater

Twenty-three cases of nitrate poisoning were diagnosed in a dairy herd due to consumption of green grass, mainly alfalfa, which was irrigated with a municipally treated wastewater. Five cows were found dead and seven fetuses were aborted. Methemoglobin (MtHb) in blood reached 41.6 ± 7.5%, while hemoglobin concentration was low: 6.9 gm dL^–1. Nitrite in plasma was 1.6 ± 0.4 mmol; the levels of nitrate in suspected grass and water were 1.48 × 10³ ppm and 1.7 × 10³ ppm, respectively. The clinical picture included difficulty in breathing, shivering and brown discoloration of the mucous membranes of the vulva, vagina, and conjunctiva. The postmortem findings included dark brown carcasses with dark, nonclotted blood in the dilated vessels. Cardiac hemorrhages, pulmonary and rumen congestion, edema and hyperemia of the mucous membranes of the abomasums and small intestine were noticed in all examined animals. The postmortem examination of aborted fetuses revealed severe ascites and hydrothorax. Affected animals responded well to the treatment with methylene blue. After one week of treatment MtHb and nitrite in plasma were significantly reduced to their minimal levels (10.5% and 0.5 mmol), respectively. One week later, green-feed and water had no evidence of nitrate. A definitive diagnosis was made based on the clinical picture, postmortem findings, high MtHb level in blood, quantitative nitrite analysis of plasma and nitrate analysis of suspected green-grass and response to methylene blue treatment.     

灌淤土施氮后土壤硝态氮的动态变化

通过室内模拟试验,探讨不同水分条件下灌淤土施用不同氮肥后硝态氮随时间的变化规律,并在田间条件下,测定不同氮肥形态和数量对土壤硝态氮含量的影响。灌淤土施氮后土壤硝态氮含量变化与土壤含水量及氮肥种类有关。施肥9d后,土壤中的硝态氮迅速增加;土壤水分低于田间持水量的50%或水分过饱和都明显影响灌淤土的硝化作用;施用大颗粒尿素产生的硝态氮最少,淋失或流失的几率小。灌淤土土体中硝态氮的残留与施氮种类及数量有直接关系。施肥使土壤表层硝态氮显著增加,施用大颗粒尿素尤为突出,但施大颗粒尿素后,60cm土体中残留的硝态氮总量最少。随着施氮量增加,表层土体中硝态氮含量增加。合理的施肥水平一般不会造成硝态氮的大量累积,而过量施氮则导致硝态氮明显积累,对通气透水性好的灌淤土,容易造成硝态氮淋失。     

Physicochemical characterization of sediments from Tajan river basin in the northern Iran

Abstract

Continuous monitoring of water quality of freshwater bodies may prevent outbreak of diseases and occurrence of hazards through employment of effective protection measures. The aim of the current investigation was to determine occurrence of water and sediment pollution in Tajan River North Iran which ultimately may be a threat to recreational beaches of Caspian Sea. Water samples were analyzed for various physicochemical parameters including pH, electrical conductivity (EC), total dissolved solids (TDS), bicarbonates, sulfates, cations, chlorides and heavy metals. The concentrations of zinc (Zn), cadmium (Cd), chromium (Cr) and lead (Pb) were determined using atomic absorption spectroscopy. Similarly, sediment samples were assessed for physicochemical characteristics including pH, EC, saturation percentage, organic matter, organic carbon, texture and cations. Overall, pH, EC, organic matter, and cation values were within acceptable limits according to USEPA water quality guidelines. However, phosphorus (P) concentration up to 5.6?mg/L was considered as “unsafe” which might result in undesirable eutrophication and increased accumulation of sediment organic content leading to excessive growth of algal species in riverine ecosystem. Heavy metal concentrations of Cd (0.08?ppm) and Pb (3?ppm) were above USEPA threshold limits which may consequently affect sustainability of Tajan River. The unacceptable levels of Cd, Pb and P may produce eutrophication of Caspian Sea coasts and damage the ecosystem.     

6种矿质元素对青菜中硝酸盐含量的影响

通过盆栽试验 ,研究了B、K、Mn、Mg、Zn、Co对青菜中硝酸盐含量的影响。结果表明 :增施硼酸钠后第 2 0天 ,青菜硝酸盐含量比对照降低 1 4 84%～ 1 9 56 % ;增施K、Mn、Mg、Zn、Co也能降低青菜硝酸盐含量。每盆增施0 1gZnSO4 后第 1 0天 ,青菜中硝酸盐含量比对照减少 1 8 96 % ,每盆增施 0 1gK2 SO4 后第 2 0天 ,青菜中硝酸盐含量比对照减少 2 1 42 % ;矿质元素的施用量对青菜硝酸盐含量影响较大。     

不同收获时期和控氮条件对水培小白菜硝酸盐含量的影响

在水培中采用收获前降低营养液浓度、完全停止供氮以及在不同时期采收等方法来研究小白菜硝酸盐含量的控制方式及其效果,结果表明:适时采收和收获前适当控氮可以降低小白菜的硝酸盐含量。在小白菜生长第26d左右硝酸盐含量最低,此后l~2d产量增长较快,此时采收品质较好;小白菜硝酸盐含量呈明显的日变化,并且与硝酸还原酶活性呈正相关,在下午16:00时左右采收硝酸盐含量最低,仅为894mg.kg-1;完全断氮7d后,小白菜硝酸盐含量显著降低,但产量也受到明显的影响。而采用低浓度营养液控氮4d左右采收既可控制硝酸盐含量又不会使产量过低。     

有机肥施用量与蔬菜硝酸盐和重金属关系初探

为控制施肥对蔬菜和土壤的负面影响,探讨蔬菜合理的有机肥施用量,在不同质地土壤上,田间试验小白菜、苦瓜、豇豆三种蔬菜施不同量有机肥,收获时测定其产量、品质、硝酸盐、重金属及试验前后土壤有机质含量。结果表明,(1)在施适量无机NPK的条件下,每造蔬菜的有机肥施用量(禽畜粪便,下同),砂土上小白菜为4500kg/hm2、苦瓜和豇豆为3000kg/hm2;壤土上,小白菜和苦瓜均宜施3000kg/hm2,豇豆则宜施4500kg/hm2;粘土上,小白菜每造只宜施1500~3000kg/hm2的有机肥。(2)有机肥必须与无机肥合理配合施用,才能获得最佳的产量和品质效果,在砂土上有机肥施得越多,蔬菜的硝酸盐含量越高,其它土壤也有类似趋势。(3)施高量(7500kg/hm2)有机肥的小白菜重金属含量最高,其次是施中量(3000kg/hm2)有机肥的,尤其是Cd。(4)施有机肥3000~4500kg/hm2 适量无机肥可使土壤有机质水平保持在种植蔬菜前的含量水平,该施肥量和方式不仅可使蔬菜高产、优质,还有利于保护土壤肥力。     

沼液对莴笋和生菜硝酸盐含量及营养品质的影响

采用盆栽试验 ,研究了不同沼液用量对莴笋、生菜硝酸盐含量和营养品质的影响。结果表明 ,施用沼液提高了莴笋、生菜株高和产量 ,降低了莴笋茎和生菜硝酸盐含量 ,有利于增加莴笋茎、叶及生菜含水量和氨基酸含量 ,生菜维生素C含量略高于对照。在施用氮磷钾化肥 (N 12 0mg·kg-1、P2 O580mg·kg-1、K2 O 10 0mg·kg-1)基础上 ,每钵增施沼液 5 0 0ml,可改善蔬菜营养品质 ,使莴笋叶和生菜硝酸盐含量分别降低 5 3.5 %和 4 5 .5 % ,同时还可使 2种蔬菜分别增产 5 1.0 %和 5 6 .7% ,为本试验条件下莴笋、生菜最佳施肥组合。     

大肠杆菌JM105中硝酸盐还原酶的制备及其性质

近年来,硝酸盐和亚硝酸盐的污染已引起普遍关注。目前,蔬菜和粮食的NO3-含量过高主要由于农药和化肥的使用、工业废水或生活污水灌溉等,食品类主要来自腌制食品和食品添加剂或防腐剂等。另外,向乳制品或食品中参碱、食盐、化肥、脏水、碱性水等也是硝酸盐污染的来源之一。因此,迫切需要快速、简便、可用于现场的硝酸盐检测方法。这就需仰赖生物酶方法,而生物酶方法的关键是酶制剂的制备和检测方法的建立。本研究通过筛选、厌氧和硝酸盐诱导培养、超声波细胞破碎和差速离心提取等方法,从大肠杆菌(Escherichia coli)JM105细胞膜中制备了硝酸盐还原酶并对其性质进行了研究。结果表明:从大肠杆菌JM105中制得的酶制剂活力很高,且在酶过量的情况下可将NO3-完全转化为NO2-,在用磷酸缓冲液清洗并冷冻保藏过夜后不含有亚硝酸盐还原酶。在加入黄素单核苷酸辅酶(FMN)后,该酶的活力可提高64%,比活力达0.42U·mg-1蛋白。该酶十分稳定,在40℃下24h活力无影响,在浓度为1mmol·L-1的Cu2 、Fe3 、Ca2 、Zn2 、Mg2 和Mo6 存在下,其活力亦不改变。因此,该酶可用于测定食品、蔬菜和环境中硝酸盐的含量。     

Nitrate levels in fresh vegetables and berries from central Japan

Nitrate concentrations in 326 recent vegetables and berries sold in Niigata, located in central Japan, were investigated. Maximum nitrate concentrations of 6600 mg kg^?1 were detected in samples of komatsuna (Brassica campestris var. perviridis) and mizuna (B. campestris L.). Mean concentrations ranged from 4 mg kg^?1(blueberry) to 3500 mg kg^?1 (mizuna). Concentrations in spinach ranged from 10 to 6000 mg kg^?1 (mean 1500 mg kg^?1). Nitrate intake from spinach and Japanese radish (Raphanus sativus) were estimated to be 0.7 and 0.8 mg kg^?1 day^?1, respectively. These values are equivalent to 19% and 23% of the acceptable daily intake (ADI). Nitrate intake at the 90th percentile was estimated to be 1.3 mg kg^?1 day^?1 (35% of the ADI) from spinach and 1.6 mg kg^?1 day^?1 (43% of the ADI) from Japanese radish.     

广东省蔬菜硝酸盐含量的调查与分析

为了解广东省蔬菜硝酸盐含量状况,分别对阳山、番禺、深圳等蔬菜生产基地和深圳市各流通领域中蔬菜的硝酸盐含量进行跟踪调查。结果表明,广东省蔬菜生产基地的蔬菜硝酸盐含量超标严重,特别是市民食用量较大的几种叶类蔬菜超标最为明显。定点监测结果表明,蔬菜的硝酸盐含量与蔬菜的新鲜程度呈明显的正相关,蔬菜越新鲜其硝酸盐含量越高;在2次定点监测中,蔬菜硝酸盐平均含量都呈现出如下的趋势:生产基地的>批发市场的>超市和农贸市场的。     

Preparation,characterization, and kinetics of nanoscale iron in nitrate nitrogen removal from polluted water

The aim of this study was to examine the production of nanoscale ions via the liquid phase reduction method and the effectiveness of the removal of nitrate nitrogen (NO₃^?–N) as well as measure the products and kinetics of the reactions. The nanoparticles obtained were approximately 50 nm in diameter and the main component was iron (Fe). This custom-made nanoscale Fe was highly positively charged, and reacted rapidly with NO₃^?–N in oxygen-free and neutral conditions at room temperature. A 90% removal rate was achieved when the reaction occurred for 30 min in simulation sample water with vigorous shaking at 250 r/min at NO₃^?–N concentrations of 30, 50, 80 or120 mg N/L. The nanometer Fe dosage was maintained throughout the experiment at 4 g/L. A first-order kinetics equation was applied to the obtained experimental data which followed a pseudo first-order reaction. Data demonstrated that the removal of nitrate nitrogen from polluted groundwater using a nanoscale Fe iron was effective and rapid.     

Pathological and toxicological investigations of chronic nitrate poisoning in cattle

In this study, three stillborn and five premature and blind calves from cows suffering from chronic nitrate poisoning were examined pathologically. The live calves were euthanized, due to a poor prognosis. Complete necropsy was performed on all the eight affected calves. Hydroperitoneum and ascites were the most predominant lesions in the stillborn calves. Edema and hemorrhage were observed in the lungs of all the calves. Hemorrhages were seen in the digestive systems of four calves. Blood samples were taken from five live calves and their mothers, and from two cows that had delivered stillborn or blind calves, for biochemical observations and measurement of methemoglobin levels. Blood values of five healthy cattle from a herd with no history of stillborn or blind calves were used as controls. Water and feed samples were taken from five different farms with a history of stillborn or blind calves and examined for nitrates. Nitrate and nitrite levels of feeds ranged from 154 to 480 and 1.5 to 20?ppm respectively; these levels can cause chronic poisoning. Levels of nitrates and nitrites in blood samples from cows and calves were found to be high. While hemoglobin values were found to be low, methemoglobin values were very high. No differences were observed between liver enzyme levels of the affected and control cattle. There were no bacteria or virus isolated from these animals, and histopathological examination revealed no indication of any other diseases.     

啤酒废水灌溉对6种蔬菜硝酸盐亚硝酸盐含量的影响

通过啤酒废水灌溉对６种蔬菜硝酸盐等的影响研究认为：啤酒废水灌溉对６种蔬菜灰分含量无明显影响;明显提高莴苣、马铃薯和甘蓝中维生素Ｃ的含量;提高韭菜、莴苣和甘蓝硝酸盐的含量;降低大葱硝酸盐的含量;可提高韭菜和马铃薯中亚硝酸盐的含量,而对于大葱、莴苣、小白菜和甘蓝中亚硝酸盐含量无明显影响     

有机无机肥配合施用对菜园土壤及蔬菜硝酸盐类动态的影响

通过田间小区试验和室内测定,研究了有机肥与化肥以不同比例配合施用对小白菜硝酸盐和亚硝酸盐含量以及土壤硝酸盐含量的影响。结果表明:有机肥与化肥配合施用可以明显降低小白菜硝酸盐含量,减少硝酸盐在土壤剖面中向下淋溶,尤以有机肥与化肥施用比例为1∶1(质量比)时小白菜产量较高,体内硝酸盐含量较低,土壤下层的硝酸盐含量也较低,达到蔬菜高产优质,生态环境清洁健康的目标。     

肥料组合对生菜硝酸盐和重金属的影响

通过田间试验研究了不同肥料组合处理对生菜硝酸盐和重金属累积的影响。结果表明，加施复合剂的3个处理对生菜硝酸盐的降低效果较好，其中施用双氰胺的组合处理在3个生长时期的降低幅度分别为24％、20．1％、65．4％，降低作用均为最大；施用植物材料处理的生菜Hg质量分数最大，高磷组合处理生菜的Cr、Cd、As和Pb质量分数最大，过磷酸钙增加了Cr、Cd、As和Pb的有效性，氯化钾对重金属影响不明显；仅加施微量元素和施用双氰胺组合处理的卫生品质最好，高磷组合处理卫生品质最差。