不同氮磷水平下中肋骨条藻对营养盐的吸收及光合特性

研究了不同氮、磷水平下中肋骨条藻(Skeletonema costatum)对营养盐的吸收动力学、生长和光合作用特性，结果表明，培养基中氮或磷浓度的改变对中肋骨条藻比生长速率影响不大，各种条件下藻细胞的比生长速率约为1．51—1．60d^-1，其中，藻细胞在低氮条件下的比生长速率略高，为1．60d^-1；低氮和低磷条件下藻细胞稳定期的生物量明显下降，分别比中氮和高氮下减少了27％和41％，而比中磷和高磷减少了64％和65％,低营养源(低氮或低磷)状态下生长的藻细胞具有较低的单位细胞表示的光饱和的光合作用速率(Pm^cell)和光合效率(α^crll)。尽管在低氮或低磷条件下生长的藻细胞单位叶绿素a的含量较低，但具有较高的活性，以单位叶绿素a表示的光饱和的光合作用速率(Pm^chla)和光合效率(α^chla)均与高氮或高磷条件下生长的藻细胞相当，这可能是不同氮、磷水平下比生长速率差异不大的原因．中肋骨条藻细胞对氮和磷吸收的适当比值(N／P)为0．8-2．6．图3表4参17     

鼠李糖脂对东海典型甲藻赤潮生物生长抑制作用的影响

探讨了铜绿假单胞菌产鼠李糖脂类生物表面活性剂对东海典型甲藻赤潮生物锥状斯式藻(Scrippsiella trochoidea)、塔玛亚历山大藻(Alexandrium tamarense)、海洋原甲藻(Prococentrum marinum)和微小原甲藻(P.minium)生长的抑制作用,并对其不同抑制作用的机理进行了初步探讨.结果表明,鼠李糖脂在一定浓度范围内对几种甲藻的生长表现出明显的抑制作用,对几种甲藻生长抑制作用的强弱顺序为:锥状斯式藻>微小原甲藻>塔玛亚历山大藻>海洋原甲藻.对不同属的甲藻,这种抑制作用可能与藻细胞本身表面的附属物、内部物质组成及个体大小有关;而对于同一属的甲藻则与各甲藻的生物膜脂肪酸组成尤其是其多不饱和脂肪酸的含量有关,即甲藻的多不饱和脂肪酸含量越低,鼠李糖脂对藻细胞生长的抑制作用越明显,反之亦然.图1表2参18     

水体氮质量浓度升高对附着藻生长和元素计量特征的影响

附着藻是浅水湖泊重要的初级生产者,水体氮磷质量浓度升高会影响附着藻的生物量和元素计量特征,从而改变牧食螺类的食物数量和质量,进而影响牧食螺类生长及其与沉水植物之间的相互关系。为了探索氮负荷升高对附着藻生物量和质量的影响,基于受控实验研究了水体氮质量浓度升高(总氮2、4、6、8和10 mg·L~(-1);总磷各处理组均为0.1 mg·L~(-1))对附着藻生长和元素计量特征的影响。实验前测定湖水氮、磷本底质量浓度,通过添加配置的营养盐溶液(氮为KNO_3,磷为KH_2PO_4),使其达到实验设计的质量浓度。每3天换1次水以控制营养盐质量浓度。在每个玻璃缸中放置5片聚乙烯附着基用于采集附着藻。实验结束时测定附着藻生物量、氮及磷含量,并计算附着藻的生长率。结果表明:随着氮质量浓度升高,附着藻的生物量和生长率呈先增加后降低趋势,在氮质量浓度为6 mg·L~(-1)时达到最大值。附着藻氮含量和氮磷比随水体氮质量浓度的升高,亦呈现先增加后降低的趋势,氮含量最大值出现在8 mg·L~(-1)处理组,氮磷比最大值出现在6 mg·L~(-1)组。附着藻氮含量与水体氮质量浓度呈显著正相关(r=0.614,P0.001)。分析认为,附着藻生长率、氮含量及氮磷比在一定范围内随着水体氮质量浓度升高而增加,当氮质量浓度超过一定范围时,三者反而降低。     

不同氮浓度下三角褐指藻生长特性和化学组成

三角褐指藻是一类海洋单细胞硅藻,富含多不饱和脂肪酸,可以作为鱼、虾、贝等理想的饵料。而近年该藻曾多次在我国沿海海域发生暴发性增殖,给当地生态环境带来了一定的影响。为了探讨不同氮浓度对三角褐指藻生长特性和化学组成的影响,设置了低氮(44 μ mol.L-1)、中氮(880 μmol.L-1)和高氮(4 400 μmol.L-1)浓度三种处理,着重测定三角褐指藻的细胞密度、比生长率、生物量、可溶性糖、蛋白质含量和叶绿素含量等指标。结果表明,高氮浓度明显地促进了藻细胞的生长繁殖。高氮浓度下的藻细胞密度、比生长率和生物量分别比低氮浓度下的提高了 5.38 倍、0.81 倍和 2.86 倍。藻生长前期,高氮浓度和中氮浓度下的生长曲线相似,呈现一个"S"型的曲线。另外,高氮浓度下的藻细胞可溶性糖、蛋白质和叶绿素a含量分别是低氮浓度下的 2.5 倍、1.5 倍和 15 倍,说明高氮浓度促进了藻细胞化学组成的转化和积累。结果揭示,氮浓度可能是导致三角褐指藻近年在我国沿海海域发生暴发性增殖的重要因素。     

不同配比土壤对平邑甜茶苗木生长和土壤微生物及土壤硝酸还原酶的影响

为探索平邑甜茶育苗质量与栽培基质理化特性的关系,通过设置不同配比的栽培基质,测定了平邑甜茶苗木生长相关指标、土壤微生物数量以及土壤硝酸还原酶活性.结果显示:(1)不同配比土壤下,微生物数量及土壤硝酸还原酶活性差异显著,其中细菌数量随植物生长先增多后减少,与植物的生长速率趋势一致;(2)壤土为主的栽培基质,土壤微生物数量和土壤硝酸还原酶活性在整个生长期均较高,平邑甜茶苗木较粗,质量较高;(3)沙土为主的栽培基质,前期根系优先发育,根冠比最大,土壤微生物数量和土壤硝酸还原酶活性在整个生长期最低.说明壤土的营养状况和物理性状更适合平邑甜茶幼苗的生长.     

4种典型有害赤潮原因种的溶血特性研究

对4种典型赤潮原因种的细胞和培养水中的溶血特性进行了研究.藻种分别是:赤潮异弯藻(Heterosigma akashiwo)的两个品系,微小亚历山大藻(Alexandrium minutum),东海原甲藻(Prorocentrum donghaiense)和微小卡罗藻(Karlodinum micrum).对各藻类的去藻上清液和超声破碎细胞提取液进行了溶血性检测,发现:几种赤潮种对鲫鱼红血细胞的溶血特性具有种间差异,同藻种的细胞与其培养水中的溶血强度存在差异.具体表现为:赤潮异弯藻具有最强的溶血性,去藻上清液的溶血性(60￣100%)远大于超声破碎细胞提取液的溶血性(30￣60%);微小卡罗藻超声破碎细胞提取液的溶血性(70%)大于去藻上清液的溶血性(30%),且是各藻超声破碎细胞提取液溶血性中最强的;东海原甲藻和微小亚历山大藻溶血性较弱,微小亚历山大藻去藻上清液的溶血性(30%)略大于超声破碎细胞提取液的溶血性(10%),东海原甲藻两部分的溶血性差异不显著.赤潮种类及其细胞内外的溶血特性在一定程度上显示了赤潮原因种在赤潮致害过程中的特征.     

海洋赤潮藻球形棕囊藻在氮磷富营养下的细胞增殖

利用常见海洋赤潮微藻球形棕囊藻(Phaeocystis globosa)为试验研究材料,以舵海洋微藻营养液为对照(1P1N:磷质量浓度为5×10-3g·L-1.氮质量浓度为75×10-3g·L-1),设置3组富磷和富氮营养处理(3P1N:磷质量浓度为15×10-3 g·L-1,氮质量浓度为75×10-3 g·L-1;1P3N:磷质量浓度为5××10-3 g·L-1,氮质量浓度为225×10-3 g·L-1;3P3N:磷质量浓度为15××10-3 g·L-1,氮质量浓度为225×10-3 g·L-1),利用细胞记数和叶绿素荧光测定等方法研究了藻细胞在不同富磷和富氮条件的增殖情况.结果显示,不同浓度磷和氮营养下的藻体荧光值变化在试验周期内均呈现"S"型曲线,表明藻细胞的生长经历缓慢期,快速期和平缓期3个阶段;同时,不同的富磷和富氮营养条件对球形棕囊藻的叶绿素荧光值有一定的影响,其中在对照1P1N下的藻体荧光值最低,在试验结束时(第10天)只有850 μg·L-1,而在3P1N,1P3N和3P3N条件下的藻体荧光值均达到900 μg·L-1以上,显著高于1P1N下的藻体荧光值,表明富磷和富氮营养可以促进藻细胞的生长增殖,但在试验设置的不同富磷和富氮营养下的藻体荧光值之间没有显著的差异.就不同磷和氮营养条件下的藻最大比生长速率而言,3P3N和3P1N条件下的最大,均达到0.77 d-1,明显高于1P1N和1P3N条件下的藻最大比生长速率(分别只有0.70 d-1和0.69 d-1).此外,试验结束时细胞密度的变化趋势与藻体荧光值相似,富磷和富氮营养条件下的细胞密度显著高于1P1N下的细胞密度,而富磷和富氮营养条件下的细胞密度间也不存在显著的差异.研究结果揭示,水体中的高磷和高氮营养浓度是导致藻细胞大量快速增殖的一个主要因素,而利用叶绿素荧光来测定藻细胞增殖是一种快速、简便,灵敏和可靠的方法,可在今后赤潮监测过程中多加利用,以能及时、准确地预测预报赤潮爆发.从而减少其对环境和经济的影响.     

海洋底栖甲藻——利玛原甲藻（Prorocentrum lima）产毒特征的研究（Studies on Toxin Production of Prorocentrum lima）

为了解海洋底栖甲藻——利玛原甲藻(Prorocentrum lima)的产毒特征,阐明腹泻性贝毒(Diarrhetic shellfishpoisoning,DSP)复杂的生物合成机制,采用酶联免疫试剂盒,对利玛原甲藻不同生长期、不同营养盐条件下毒素生成情况进行了研究.结果显示,不同生长期单个利玛原甲藻细胞中大田软海绵酸(Okadaic acid,OA)的含量明显不同,平台期时OA含量最高,与对数中期存在显著差异(p<0.05).低N、P条件下藻的生长状况较差,所能到达的藻密度明显低于对照组(f/2培养基);藻细胞中OA的总含量也低于对照组,但单个藻细胞中OA的含量明显高于对照组(p<0.05).以上结果提示,利玛原甲藻DSP毒素的产生可能与藻所处的环境和藻的生理状态等有关.     

不同氮磷浓度对盘星藻生长的影响

水体富营养化是当前一个严重的环境问题,而营养因子是引起水华的重要元素.文章通过实验室配水来模拟在不同氮、磷浓度下盘星藻(Pediaslrum sp)的生长情况.共设置了6个氮质量浓度梯度:0.1、0.5、0.9、1.3、1.7、2.1 mg·L-1对盘星藻的生长影响,在1.7mg·L-1的氮质量浓度下盘星藻的相对增长常数Kin=0.84.设置6个磷质量浓度梯度:0.01、0.03、0.07、0.10、0.14、0.19 mg·L-1对盘星藻的生长影响,在0.14 mg·L-1的磷质量浓度下盘星藻的最大比增长率为μmax=0.83.从水质指标变化看,pH和DO对细胞的生长状况有一定的预先指示作用;浊度与细胞生长状况呈正相关关系,在氮质量浓度影响下电导率与细胞生长状况呈正相关关系,在磷质量浓度影响下电导率与细胞生长状况呈负相关关系.     

铁浓度诱导的三角褐指藻生长和生化组分变化

采用试验生态学方法,以海洋硅藻三角褐指藻(Phaeodactylum tricornutum)为研究材料,设置一系列铁浓度处理(3.15mg·L-1、6.30 mg·L-1、9.45 mg·L-1、18.90 mg·L-1和34.65 mg·L-1),着重测定藻液光密度(OD450)、比生长率、藻细胞密度、藻生物量、叶绿素含量和蛋白质含量等生理生化指标,探讨铁浓度对海洋微藻生长特性和生化组分的影响.结果表明,铁浓度对三角褐指藻的生长状况产生了显著的影响.三角褐指藻经培养48 h后,不同铁浓度下的藻液光密度(OD450)存在显著的差异,6.30 mg·L-1铁浓度下的藻液光密度值(OD450)最高,而随着铁浓度的进一步升高,藻液光密度值(OD450)却明显降低;比生长率和藻细胞密度在3.15 mg·L-1到9.45 mg·L-1铁浓度范围内随着铁浓度升高而增大(最大值分别约为0.609 d-1和1200×104 cell·mL-1),但高于9.45 mg·L-1的铁浓度显著降低了比生长率和藻细胞密度;在试验所设置的铁浓度范围内,藻生物最表现出随铁浓度的升高而增大的趋势,34.65 mg·L-1铁浓度下的藻生物量高达0.460 mg·ML-1.同样地,微藻叶绿素a含量和蛋白质含量也明显地受到铁浓度的影响.在3.15 mg·L-1到18.90 mg·L-1铁浓度范围内,叶绿素a含量逐渐增高(最大值为2.41 mg·L-1);同样地,蛋白质含量在9.45 mg·L-1.铁浓度下达到最大值(0.153 mg·mL-1),而随着铁浓度的逐渐升高,叶绿素和蛋白质含量却明显降低.研究结果表明.铁浓度诱导海洋微藻的生长及代谢发生变化.一定较高浓度的铁显著地促进了藻细胞的生长繁殖和藻细胞化学组分的转化和积累.这些发现将有利于加深认识铁浓度在海洋生态系统中扮演的角色,进一步明确赤潮爆发的生理生态机制,从而有助于人们采取有效的预测、预防和管理措施以降低赤潮的危害.     

Nitrate production and availability in residential soils

The rapid increase in residential land area in the United States has raised concern about water pollution associated with nitrogen fertilizers. Nitrate (NO3-) is the form of reactive N that is most susceptible to leaching and runoff; thus, a more thorough understanding of nitrification and NO3(-) availability is needed if we are to accurately predict the consequences of residential expansion for water quality. In particular, there have been few assessments of how the land use history, housing density, and age of residential soils influence NO3(-) pools and fluxes, especially at depth. In this study, we used 1 m deep soil cores to evaluate potential net nitrification and mineralization, microbial respiration and biomass, and soil NO3(-) and NH4+ pools in 32 residential home lawns that differed by previous land use and age, but had similar soil types. These were compared to eight forested reference sites with similar soils. Our results suggest that a change to residential land use has increased pools and production of reactive N, which has clear implications for water quality in the region. However, the results contradict the common assumption that NO3(-) production and availability is dramatically higher in residential soils than in forests in general. While net nitrification (128.6 +/- 15.5 mg m(-2) d(-1) vs. 4.7 +/- 2.3 mg m(-2) d(-1); mean +/- SE) and exchangeable NO3(-) (3.8 +/- 0.5 g/m2 vs. 0.7 +/- 0.3 g/m2) were significantly higher in residential soils than in forest soils in this study, these measures of NO3(-) production and availability were still notably low, comparable to deciduous forest stands in other studies. A second unexpected result was that current homeowner management practices were not predictive of NO3(-) availability or production. This may reflect the transient availability of inorganic N after fertilizer application. Higher housing density and a history of agricultural land use were predictors of greater NO3(-) availability in residential soils. If these factors are good predictors across a wider range of sites, they may be useful indicators of NO3(-) availability and leaching and runoff potential at the landscape scale.     

Nitrate metabolism in abyssal waters

Activities of nitrate assimilation and nitrate reduction were measured 50 cm above the ocean floor (5,845 m and 5,207 m) by an in situ ¹⁵N tracer technique at stations in the subtropical (28°29.8′N; 144°58′E) and subarctic (44°10.2′N; 154°03′E) western North Pacific Ocean. Nitrate assimilation ranged from 0.009 to 0.11 μg-at N/1/day, and nitrate reduction from 0 to 0.42 μg-at N/1/day in the presence of added peptone and yeast extract. Nitrate assimilation was higher than nitrite formation at the southern station, but the reverse was the case at the subarctic station. No correlation was observed between bacterial growth and nitrate metabolizing activities. Data are also presented on the effect of hydrostatic pressures upon nitrate metabolism by microbial populations in the surface waters.     

Nitrate toxicity toPenaeus monodon protozoea

Increased levels of nitrate occur in natural waters due to pollution, and in aquaculture systems from nitrification and addition of microalgal cultures for feeding. Static bioassays showed that significant mortality of larvalPenaeus monodon (Fabricius) occurred within 40 h at nitrate concentrations as low as 1 mg NO ₃ ^- l^–1. Sublethal effects of this concentration resulted in changes to ganglionic neuropiles and muscles. At higher concentrations (10 and 100 mg NO ₃ ^- l^–1), additional tissues were affected including the hypodermis, midgut and proventriculus. This is the first report of toxicity to a marine organism of nitrate at concentrations normally present in enclosed seawater and mariculture systems. The results are discussed in terms of management of culture systems and of natural marine ecosystems containing elevated levels of nitrate.     

脱氮硫杆菌对废水中硫氮的脱除

为脱除废水中高浓度的硫氮,首先对脱氮硫杆菌(Thiobacillus denitrificans)的生长曲线和驯化期间营养液pH的变化进行了测定,确定了脱氮硫杆菌合适的使用条件.然后检测了接菌后废水中的S2-浓度控制在400 mg/L时合适的硫氮比以及脱氮硫杆菌对NO3-的去除率.结果表明,处理富含硫氮的废水时,当硫氮比控制在5:3、S2-浓度控制在400mg/L时,脱氮硫杆菌对NO3-的去除率可达63.19%,同时S2-转化成硫酸盐或可回收的单质硫,使废水的硫氮污染得到了有效的控制.     

Nitrate reductase in Peru current phytoplankton

Nitrate reductase (NR) activity was assayed by measuring the NADH-dependent formation of nitrite in phytoplankton extracts. NR specific activity increased with the nitrate concentration of the water in upwelling areas of the Peru Current. The temperature optimum for NR for natural phytoplankton was 15° to 20°C. NR activity showed diel periodicity, with maximum activity about noon and minimum activity near midnight local time. Rate of nitrate reduction in the extracts averaged only about 15% of the rate of nitrate assimilation in the whole cells.     

Nitrate reductase activity in Zostera marina

Eelgrass (Zostera marina L.) has access to nutrient pools in both the water column and sediments. We investigated the potential for eelgrass to utilize nitrate nitrogen by measuring nitrate reductase (NR) activity with an in vivo tissue assay. Optimal incubation media contained 60 mM nitrate, 100 mM phosphate, and 0.5% 1-propanol at pH 7.0. Leaves had significantly higher NR activity than roots (350 vs 50 nmoles NO ₂ ^– produced g FW^–1 h^–1). The effects of growing depth (0.8 m MLW, 1.2 m, 3.0 m, 5.0 m) and location within the eelgrass meadow (patch edge vs middle) on NR activity were examined using plants collected from three locations in the Woods Hole area, Massachusetts, USA, in July 1987. Neither depth nor position within the meadow appear to affect NR activity. Nitrate enrichment experiments (200 M NO ₃ ^– for 6 d) were conducted in the laboratory to determine if NR activity could be induced. Certain plants from shallow depth (1.2 m) showed a significant response to enrichment, with NR activity increasing from >100 up to 950 nmoles NO ₂ ^– g FW^–1 h^–1 over 6 d. It appears that Z. marina growing in very shallow water (0.8 m) near a shoreline may be affected by ground water or surface run-off enrichments, since plants from this area exhibited rates up to 1 600 nmol NO ₂ ^– g FW^–1 h^–1. Water samples from this location consistently had slightly higher NO ₃ ^– concentrations (1.4 M) than all other collection sites (0.7 M). Thus, it is possible that chronic run-off or localized groundwater inputs can create sufficient NO ₃ ^– enrichment in the water column to induce nitrate reductase activity in Zostera leaves.     

芜湖市蔬菜硝酸盐污染状况及安全处理效果

对芜湖市蔬菜集散市场的菠菜、青菜、黄瓜、青椒、番茄、马铃薯、莴苣、白萝卜、卷心菜及腌制雪里蕻10种常见蔬菜的硝酸盐含量进行了测定,并分析了低温储存及洗洁精清洗对蔬菜硝酸盐含量的影响。结果表明,洗洁精去除蔬菜中硝酸盐效果较好,常规洗菜前先在"白猫"牌洗洁精水溶液中浸泡15min,可使硝酸盐平均含量降低近100mg·kg-1。随着放置时间的增加,硝酸盐逐渐分解,而冰箱内低温存放,可减缓蔬菜硝酸盐含量的下降。根据GB18406.1—2001《农产品安全质量无公害蔬菜安全要求》对10种蔬菜进行的评价发现,叶菜类蔬菜中菠菜、青菜硝酸盐含量严重超标,其他所测蔬菜均未超标。     

上海市郊蔬菜硝酸盐含量及评价

对上海市不同种类和不同种植方式下的蔬菜硝酸盐含量进行测定，以期了解上海市蔬菜的硝酸盐含量现状。结果表明，不同种类蔬菜硝酸盐含量(设为Y)由高到低依次为：Y(绿叶菜类)→Y（豆类)→Y（瓜类)→Y（茄果类)→Y（食用菌类)；叶菜类的硝态氮含量较高，平均为463.95mg／kg；其次是豆类，平均值为141．91mg／kg；瓜类、茄果类、食用菌类蔬菜的硝态氮平均含量较低，分别为102．38mg／kg，38．81mg／kg，26．29mg／kg。耕作和种植制度均能影响硝酸盐在土体中的积累和迁移，由于管理方式不同，同一种蔬菜品种的NO3^--N质量分数(设为Y)由高到低依次为：y(大棚蔬菜)→y(露地蔬菜)→y(传统自留地蔬菜)。所有样品中叶菜类蔬菜的硝酸盐含量超过一级标准的占57.1％，污染指数最高的达3．50，污染较重；豆类、瓜类、茄果类、食用菌类样品中硝酸盐没有超过一级标准的，污染较轻。     

Nitrate reductase for nitrate analysis in water

Nitrate analysis in water is one of the most frequently applied methods in environmental chemistry. Current methods for nitrate are generally based on toxic substances. Here, we show that a viable alternative method is to use the enzyme nitrate reductase. The key to applying this Green Chemistry solution for nitrate analysis is plentiful, inexpensive, analytical grade enzyme. We demonstrate that recombinant Arabidopsis nitrate reductase, expressed in the methylotrophic yeast Pichia pastoris, is a highly effective catalyst for nitrate analysis at 37°C. Recombinant production of enzyme ensures consistent quality and provides means to meet the needs of environmental chemistry.     

中国北方土壤硝态氮的累积及其对环境的影响

运用统计资料和调查研究资料，揭示中国氮肥用量在地区之间和作物之间分配的不平衡现象，经济发达的东南部地区和城郊地区氮肥施用量远高于西北部地区，经济作物远高于粮食作物，氮肥短缺和过量施用并存。中国北方某些地区土壤剖面硝态氯的大量累积对水体环境构成了某种程度的威胁。由于大田作物获得较高产量的“平均适宜施氮量(N150—180kg／hm^2)”与氮素环境安全指标尚有一定距离，中国完全可以实现水体环境安全和农业高产优质的双重目标。氮肥对水体环境的影响主要是由不合理大量施用氮肥造成的。因此，中国应制定施肥技术标准和法规，鼓励农民降低氮肥用量。