where k (M− 2 s− 1) can be determined from the
in the pH range 2 to 5, from 5 to 40 °C and 0.01 to 1 M.The effect of pH and ionic strength on the reaction suggest that the rates are due to
where H2A = H2CrO4, HA = HCrO4−, H2B = H2SO3 and HB = HSO3−. The overall rate expression over the investigated pH range can be determined from
k=kH2A–H2B(αH2A)(αH2B)2+kHA–H2B(αHA)(αH2B)2+kH2A–HB(αH2A)(αHB)2
with kH2A−H2B = 5.0 × 107, kHA–H2B = 1.5 × 106 and kH2A–HB = 6.7 × 107.Fe(III) in the range 1.5 to 20 μM exerts a small catalytic effect on the reaction and significantly lowers the initial concentration of Cr(VI) compared to the nominal value. Contrary to Fe(III), formaldehyde (20 to 200 μM) reacts with S(IV) to form the hydroxymethanesulfonate adduct (CH2OHSO3−), which does not react with Cr(VI). Major cations Mg2+ and some minor elements such as Ba2+ and Cu2+ did not affect the rates. The application of this rate law to environmental conditions suggest that this reaction may have a role in acidic solutions (aerosols and fog droplets). This reaction becomes more important in the presence of high Fe(III) and low HMS concentrations, contributing to affect the atmospheric transport of chromium species and the distribution of redox species of chromium, which reach surface water from atmospheric depositions.  相似文献   

12.
非晶态磷酸锡去除高盐介质中Pb（Ⅱ）研究     
祝春水  王丽萍  贡梅玲  曹文秀 《海洋科学》2011,35(11):90-96
利用合成的非晶态磷酸锡作为吸附剂, 研究了多种因素（pH、吸附时间、初始浓度、温度、离子强度）对吸附剂吸附水溶液中Pb2＋的影响。结果表明, 非晶态磷酸锡对Pb2＋的吸附量随着pH（3～6）以及吸附时间的增大而增加。用Freundlich、Langmuir 模型对等温吸附数据进行处理, Langmuir 方程拟合效果最...  相似文献   

13.
中国近海的蔓足类 Ⅳ.花笼科     
任先秋 《海洋科学集刊》1984,(23):165-182
花笼亚目(Verrucomorpha)是蔓足类中较独特的一个类群,它的左右两侧売板不对称，一侧背板及楯板与壁板愈合而不能活动。它们一般栖息于深度超过100米的较深水域,固着于岩石、泥块、贝壳、海胆棘、海绵骨针或其他物体上,分布范围较广。这类动物一般不易采到,在我国过去尚未见报道。本文是我国海区花笼类第一篇研究报告。搞清它们的种类对分析底栖生物群落组成和分布具有一定的意义。 本文根据的材料是1975-1981年东海大陆架调查和1959-1960年全国海洋综合调查采集的底栖动物标本。由于深海调査采集不够,标本数量不多,共发现6种,分隶于花笼科 Family Verrucidae 花笼属 Genus Verruca 的4个亚属,皆为我国首次记录。该6种栖息的水深从110米到2150米,其中驼背花笼 Verruca( Altiverruca) gibbosa为世界各大洋的广布种；雕板花笼 Verruca(Metaverruca) sculpta为分布于三大洋的环热带种；其余4种为印度一西太平洋暖水种。  相似文献   

14.
Binding of thorium(IV) to carboxylate, phosphate and sulfate functional groups from marine exopolymeric substances (EPS)   总被引：2，自引：0，他引：2  
Nicols G. Alvarado Quiroz  Chin-Chang Hung  Peter H. Santschi 《Marine Chemistry》2006,100(3-4):337
Th(IV) isotopes are important proxies in oceanographic investigations, and are used as tracers of particle dynamics and particulate organic matter (POC) fluxes out of the euphotic zone through the use of 234Th/POC ratios. These approaches rely on empirically determined and variable POC to 234Th ratios, which might be controlled, in parts, by the abundance of exopolymeric substances (EPS). EPS contain acidic polysaccharides (APS) and are excreted by both phytoplankton and bacteria. To this end, radiotracer experiments with EPS from microbial cultures were conducted to determine the binding environment of 234Th(IV)-binding ligands in colloids and suspended particles in marine systems. In these experiments, the 234Th distribution during isoelectric focusing (IEF) and polyacrylamide gel electrophoresis (PAGE) was related to the functional group composition of EPS and of colloidal organic matter (COM) isolated from the Gulf of Mexico (GOM) using cross-flow ultrafiltration. EPS was extracted from phytoplankton (Emiliania huxleyi and Synechococcus elongatus) and bacteria (Sagittula stellata and Roseobacter gallaeciensis) cultures by repeated alcohol precipitation. Phosphate and sulfate concentrations were determined using ion chromatography (IC). IEF profiles indicated that 49% to 65% of the 234Th-labeled EPS from plankton and bacteria as well as COM samples from the GOM was found concentrated below pH of 4, near an isoelectric point, pHIEP, of about 2. The carboxylic acid maxima for extracted EPS and COM samples appeared close to the pHIEF of 234Th(IV). The phosphate maximum appeared at the same pHIEF as 234Th(IV) for EPS from R. gallaeciensis and S. elongatus. The sulfate maximum was found at the same pHIEF as 234Th(IV) for EPS from S. elongatus and COM. The molecular weight (MW) of the strongly Th(IV)-binding ligand varied from 1 to 14 kDa, depending on the species, but was about 10 kDa in COM. Thus, depending on the species of plankton or bacteria, the MW and specific functional group composition of the strongly 234Th(IV)-binding amphiphilic biomolecule can vary. Therefore, different acidic functional groups can, at times, contribute to the binding of Th(IV) to the EPS chelating ligand, which can also have different MWs. This implies that the binding environment for Th(IV), which is present at total concentrations at least a million times lower than the acid functional groups, consists of strong polydentate chelate complexes in clustered structures of carboxylate, sulfates and/or phosphates. The combination of strongly chelating groups and amphiphilicity gives this biomolecule the unique properties of a “sticky” ligand.  相似文献   

15.
Acute toxicity of tributyltin to the Caprellidea (Crustacea: Amphipoda)     
Ohji M  Arai T  Miyazaki N 《Marine environmental research》2005,59(3):197-201
In order to compare the acute toxicity of tributyltin (TBT) between sexes, five species of caprellid amphipods were exposed to seven levels (0, 0.001, 0.01, 0.1, 1, 10 and 100 microg l(-1)) of TBT for 48 h at 20 degrees C. The 48-h LC50 values in male and female were 1.3-6.4 microg TBTCl l(-1) and 1.2-8.6 microg TBTCl l(-1), respectively. No sex-specific differences of the acute toxicity of TBT were observed in the caprellids. These findings suggest that the risk of survival in response to exposure to TBT between sexes is similar in the caprellids.  相似文献   

16.
中国南海水螅水母纲(刺胞动物门)分类研究Ⅳ:高手水母科(花水母亚纲)   总被引：1，自引：1，他引：0  
郭东晖  许振祖  黄加祺  林茂  王春光 《海洋学报(英文版)》2018,37(10):98-103
本文复查了中国南海丝螅水母目高手水母科的所有属，解决了该科和一些属、种存在的分类问题，并给予更新的鉴别。以前，无手单肢水母Nubiella atentaculata Xu and Huang，2004包含在单肢水母属内，现变换为拟单肢水母新属Paranubiella n.gen.，隶属于高手水母科内，原无手单肢水母新组合为无手拟单肢水母Paranubiella atentaculata（Xu and Huang，2004） n.comb.。本文记述了二个新种：南海拟单肢水母，新种Paranubiella nanhaiensis sp.nov.和无突单肢水母，新种N.apapillaris sp.nov.。此外编制了高手水母科已知属和单肢水母属已知种的检索表，总结了中国南海高手水母科已知种名录。模式标本保存于国家海洋局第三海洋研究所。  相似文献   

17.
Total selenium and selenium (IV) in the James River estuary and southern Chesapeake Bay     
Kazufumi Takayanagi  George T.F. Wong 《Estuarine, Coastal and Shelf Science》1984,18(1):113-119
The concentrations of total selenium (Se) and Se (IV) were determined in the surface waters of 30 stations located in the James River and southern Chesapeake Bay. The concentrations of total Se and Se (IV) ranged from 0·28 to 1·91 nM and from 0·07 to 1·36 nM, respectively, between salinities of 31·78 and 0·06‰. The concentration of Se (VI), calculated as the difference between the concentrations of total Se and Se (IV), ranged from 0·08 to 0·67 nM. While total Se seemed to be conservative in this study area at salinities above 0·36‰, Se (IV) might have been removed during estuarine mixing. The removal of Se (IV) occurred primarily at salinities below 4‰ possibly via the oxidation of Se (IV) to Se (VI).  相似文献   

18.
养殖水体中氨氮对大菱鲆的急性毒性效应研究     
李之乡  王伟继  胡玉龙  吕丁  吴欢欢  栾生  孔杰 《海洋科学》2017,41(10):109-116
为了评估大菱鲆(Scophthalmus maximus)耐氨氮性状的遗传参数和为循环水养殖大菱鲆提供科学指导,作者研究了养殖海水中氨氮对4月龄和8月龄大菱鲆的急性毒性效应,同时对比了氨氮对白化和正常个体、雌性和雄性个体的急性毒性效应差别。结果表明:非离子氨对4月龄大菱鲆的24、48、72、96 h LC50分别为2.19、1.94、1.80、1.72 mg/L,对8月龄大菱鲆的24、48、72、96 h LC50分别为3.64、3.02、2.93、2.86 mg/L,非离子氨对4月龄和8月龄大菱鲆的安全质量浓度分别为0.17和0.29 mg/L;氨氮对白化和正常大菱鲆以及雌性和雄性大菱鲆的急性毒性效应均没有显著性差异,研究结果为进一步选育大菱鲆的耐氨氮品系提供科学依据。  相似文献   

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1.
用化学品对藻类毒性测试的标准试验方法,分别研究了硫属元素Se(Ⅳ)和Te(Ⅳ)单组分对钝顶螺旋藻(Spirulina platensis)的毒性效应,用相加指数法评价了Se(Ⅳ)和Te(Ⅳ)双组分对螺旋藻的联合毒性效应.结果表明,Te(Ⅳ)对螺旋藻的毒性大于Se(Ⅳ),其EC50,96h分别为125.2 mg/L和36.1 mg/L;Se(IV)和Te(Ⅳ)的联合毒性效应为拮抗作用, 其EC50,96h为103.1 mg/L.  相似文献   

2.
杨芳  涂芳  刘杰  郑文杰 《海洋科学》2012,36(6):84-88
用光谱法研究了 Te(IV)对螺旋藻(Spirulina maxima)的胁迫作用.各实验组添加 Te(IV)的时间均在第5~7天,累积添加质量浓度为从450~650 mg/L.结果表明,各 Te(IV)胁迫实验组中活藻体悬浮液的吸收光谱特征峰强度均不同程度地下降.而在440、580 nm 激发所得的荧光发射光谱峰位置不变,峰强度下降.但干粉的荧光光谱与活藻体悬浮液有明显不同,干粉中的藻胆体的能量传递过程受阻.各试验组干藻粉的红外光谱无明显差异  相似文献   

3.
在水温15.5-17.0℃的静水条件下,以Hg2+、Cd2和Se4+对刺参幼参进行了单一毒性和联合毒性实验.联合毒性实验采用等毒性配比法,并以Marking相加指数评价联合毒性效应.单一毒性实验结果表明,Hg2+、Cd2+、Se4+对刺参幼参急性毒性的96h半致死质量浓度(LC50)分别为0.0912、4.6433和0.7413mg/L,三者对幼参的毒性大小依次为Hg2+>Se4+>Cd2+.Hg2+、Cd2+、Se4+对刺参幼参的最大容许质量浓度分别为0.0009、0.0464、0.0074mg/L.联合毒性实验结果表明,当Hg2+-Cd2+、Hg2+-Se4+以及Cd2+-Se4+分别以等毒性混合物共存时,它们对刺参幼参在24h、48h、72h和96h的联合毒性均为拮抗作用;当Hg2+-Cd2+-Se2+三者以等毒性混合共存时,它们对刺参幼参在24h、48h、72h和96h的联合毒性仍为拮抗作用.讨论了Hg2+、Cd2+、Se4+对刺参幼参联合毒性效应的机制.  相似文献   

4.
原子荧光光谱法测定天然水体中的Se(IV)   总被引：3，自引：0，他引：3       下载免费PDF全文
姚庆祯  张经 《海洋科学》2003,27(4):63-67
采用氢化物—原子荧光光谱法(HG-AFS)，在1mol/L HCl介质中用KBH4作还原剂测定天然水体中痕量Se(IV)。利用正交实验对实验条件进行了优化选择，在确定的条件下，方法的检出限为0．06nmol／L，对Se(IV)含量为0．51nmol／L和1．14nmol／L的样品分析精密度为3．9％和3．5％，方法的回收率为96％-105％，线性范围为0．06—250nmol/L。在不同介质中工作曲线的变动范围小于5％。  相似文献   

5.
Cd2+和Cu2+对泥蚶的急性毒性和联合毒性试验   总被引：1，自引：0，他引：1  
为了解重金属Cd2+和Cu2+对泥蚶的毒害程度和泥蚶对重金属Cd2+和Cu2+的解毒能力,用毒理学实验方法研究了Cd2+和Cu2+对泥蚶(Tegillarca granosa)的急性毒性和联合毒性效应。结果表明:Cd2+、Cu2+对泥蚶的96 h半致死质量浓度分别为6.189、0.460 mg/L;安全质量浓度分别为0.062、0.005 mg/L;相对毒性Cu2+Cd2+。在1︰1毒性单位的联合作用下,Cd2+和Cu2+对泥蚶96 h的半致死质量浓度分别为1.984、0.147 mg/L;安全质量浓度分别为0.020、0.001 mg/L。2种重金属离子的联合毒性大于任一重金属离子的毒性,联合毒性表现为协同作用。  相似文献   

6.
为丰富海洋环境中多溴联苯醚污染对浮游动物毒性效应的研究,本文采用不同浓度的2种多溴联苯醚BDE-47和BDE-209作为胁迫因子,以褶皱臂尾轮虫(Brachionus plicatilis)为受试生物,研究其单一及联合急性毒性效应。研究显示:单一急性毒性作用时,BDE-47胁迫对轮虫的48、72和96hLC50分别为2.113、0.376、0.163mg/L,均小于BDE-209各相应的LC50值,分别为11.162、1.237、0.295mg/L,说明BDE-47对褶皱臂尾轮虫的急性毒性大于BDE-209;二者联合作用时,分别采用浓度1∶1和毒性1∶1进行试验,应用Marking相加指数法计算AI(Additive index),评价二者对轮虫的联合毒性,2种试验配比方式得到的结果类似,暴露时间分别为24、48h时AI0,联合作用结果均为协同作用;72、96h时AI0,均表现为拮抗作用。结果表明,96h内随着暴露时间的增加,BDE-47和BDE-209对其联合毒性作用从协同作用转变为轻微的拮抗作用。  相似文献   

7.
通过对银鲫(Carassiusauratusgibelio)幼鱼(L=3.56±0.28cm)的NaCl浓度(pH=8.80±0.10)及碱度(pH=8.84±0.26)的急性毒性试验，用概率单位法求得其24，48，96h的半致死浓度(LC50值)NaCl浓度分别为11.53、10.77、8.58g/L；碱度分别为98.74、79.49、64.19mmol/L。在此基础上采用水生毒理联合效应相加指数法进行了氯化钠与碳酸氢钠浓度的联合毒性实验(浓度=11)，结果在96h内二者的关系全部为协同作用,且其协同性逐渐减弱并趋向于相加作用。  相似文献   

8.
以彩虹明樱蛤养殖壳高优势组(平均壳高为17.35±1.01mm)为实验动物,进行4种重金属离子Hg2 、Cr6 、Cu2 、Zn2 对彩虹明樱蛤的急性毒性和加和等毒性强度联合毒性试验。结果表明,彩虹明樱蛤对重金属的耐药性均随实验时间延长而缓慢降低,4种重金属离子毒性大小依次为Cu2 、Hg2 、Zn2 、Cr6 ,其对彩虹明樱蛤96h的半致死质量浓度分别为0.0554mg/L、0.1099mg/L、2.2605mg/L、19.6277mg/L;Hg2 、Cr6 、Cu2 、Zn2 离子两两组合在加和等毒性强度下对彩虹明樱蛤96h联合急性毒性所呈现的致毒特征与离子间毒性强度匹配情形密切相关。  相似文献   

9.
铜和锌对刺参幼参的联合毒性作用   总被引：3，自引：0，他引：3  
采用等毒性配比法,研究了金属离子 Cu2+ 和 Zn2+ 对刺参幼参的联合毒性,并以 Marking 相加指数 ( AI ) 评价联合毒性效应.实验结果表明,当 Cu2+ 和 Zn2+ 以等毒性混合共存时,Cu2+ 对刺参幼参在24 h、48 h、72 h和96 h 的半致死质量浓度 ( LC50 ) 分别为0.351 7、0.283 3、0.249 5和0.234 8 mg/L;Zn2+ 对刺参幼参在24 h、48 h、72 h和96 h的 LC50 分别为 5.061 0、3.223 4、2.469 6和2.163 5 mg/L.由此可见,Cu2+ 对幼参的毒性大于 Zn2+.二者以等毒性混合对刺参幼参在 24 h、48 h、72 h和96 h的相加指数 AI值分别为 -0.931 5、-1.499 0、-1.834 2和-2.065 2,其对幼参24 h、48 h、72 h和96 h的联合毒性均为拮抗作用;并且随着暴露时间的延长,拮抗作用增强.  相似文献   

10.
3种植物激素对螺旋藻生长和代谢产物含量的影响   总被引：1，自引：0，他引：1       下载免费PDF全文
用单因素分析法研究6一苄基氨基嘌呤(6-BA)、萘乙酸(NAA)和赤霉素(GA)3种植物激素对螺旋藻生长和代谢产物含量的影响.结果显示,添加NAA(0.4 mg/L)和GA(1.0 mg/L)分别使钝顶螺旋藻(Speruli-na pzatensis)和极大螺旋藻(Spirulina maximum)生物量达到最大值,与对照相比提高了49.1%和65.2%,比生长速率增加了66.7%和28.6%.同样,激素可以显著地影响螺旋藻的代谢产物含量.对于钝顶螺旋藻,GA(0.1 mg/L)使胞外总糖含量增加5倍;GA(0.3 mg/L)使胞内总糖含量提高5倍;6-BA(0.2 mg/L)使胞内蛋白含量提高27.8%;NAA(0.2 111g/L)使SOD酶比活力提高3.47倍.对于极大螺旋藻,GA(0.3 nlg/L)使胞外总糖含量增加1.32倍,使胞内总糖含量提高2倍;NAA(1.6mg/L)使胞内蛋白含量提高66.7%,6-BA(1.6 mg/L)使SOD酶比活力提高3.47倍.因此植物激素对螺旋藻生长和代谢产物合成有明显的促进作用,该结果为高密度规模化生产奠定基础.  相似文献   

11.
The rates of the reduction of Cr(VI) with S(IV) were measured in deaerated NaCl solution as a function of pH, temperature and ionic strength. The rates of the reaction were found to be first order with respect to Cr(VI) and second order with respect to S(IV), in agreement with previous results obtained at concentrations two order higher than the present study. The reaction also showed a first-order dependence of the rates on the concentration of the proton and a small influence of temperature with an apparent energy of activation ΔHapp of 22.8 ± 3.4 kJ/mol. The rates were independent of ionic strength from 0.01 to 1 M. The rate of Cr(VI) reduction is described by the general expression
−d[Cr(VI)]/dt=k[Cr(VI)][S(IV)]2
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