重金属镉对铜藻生长及其生物活性成分积累的影响

为研究水体重金属污染对经济海藻的生长和品质造成的严重影响,以经济褐藻铜藻Sargassum horneri为研究对象,在温度为15℃的条件下,研究了由Cd Cl2·2.5H2O配制不同浓度(0、0.1、0.5、1.0、5.0 mg/L)的重金属镉胁迫对铜藻生长、光合色素、可溶性糖、可溶性蛋白等生理生化指标,以及对生物活性成分(岩藻黄素、褐藻胶和褐藻多酚)积累的影响。结果表明:对照组藻体的特定生长率(SGR)在15 d内持续升高,0.1、0.5 mg/L Cd处理组的SGR在试验前10 d内逐渐升高,然后保持稳定至第15天,1.0 mg/L处理组的SGR随着培养时间的延长呈波动变化状态,而5.0 mg/L处理组的SGR呈先升高后降低的趋势;藻体的各项生理生化指标随胁迫时间呈不同的变化趋势,但在试验第15天时,各胁迫组藻体的叶绿素a、类胡萝卜素和可溶性蛋白含量均显著低于对照组(P<0.05),而可溶性糖含量则显著高于对照组(P<0.05);铜藻的岩藻黄素和褐藻多酚含量在不同浓度的Cd胁迫下均有极大程度的下降,且Cd胁迫浓度越高,降幅越大,而褐藻胶含量在Cd浓度≤0.5 mg/L胁迫下未有显著变化(P>0.05),在Cd≥1.0mg/L时显著下降(P<0.05)。研究表明,在铜藻产业化开发应用过程中,其养殖海域的重金属污染是需要考虑的重要因素。     

冰乙酸改性狐尾藻对铜离子的吸附

以廉价而且易种植培育的沉水植物为原料,吸附重金属离子,降低废水中重金属离子浓度.采用冰乙酸对沉水植物狐尾藻进行改性,然后,取酸改性狐尾藻置于600 mg/L,pH=4的硝酸铜溶液搅拌处理2h,测试吸附重金属Cu~(2+)的能力.结果表明,狐尾藻经冰乙酸改性之后,吸附性能更好,对废水中重金属Cu~(2+)的吸附效率达到92.2%,高于未改性狐尾藻的吸附效率(85.6%).三次循环吸附后,吸附效率仍达到86.3%,拟合Elovich方程,第一次循环吸附R~2=0.9998,第四次循环吸附R~2=0.9999,线性关系均较好,表明拟合的二级动力学方程得到的最大吸附量与实验值基本吻合,为生物吸附材料的开发提供了理论依据.     

萱藻中褐藻多糖硫酸酯的纯化及其组分分析

以从大连沿海新鲜萱藻Scytosiphon lomentaria中提取的褐藻多糖硫酸酯为原料,采用DEAE-Sepharose Fast Flow弱阴离子交换层析的方法对萱藻褐藻多糖硫酸酯粗提取物进行分离纯化,对纯化后各组分的硫酸根、总糖含量进行了测定,并进行组分分析。结果表明:各组分的硫酸根含量分别为10.64%、10.47%、11.93%、21.13%,多糖含量分别为46.56%、55.88%、50.06%、73.65%;通过单糖分析、红外光谱法和核磁共振波谱法分析,显示F-1、F-2含有鼠李糖,F-0、F-3出现岩藻糖的C6信号峰。本研究结果为下一步开发萱藻资源、了解其功效关系提供了理论基础。     

树皮藻岩藻聚糖硫酸酯的纯化及其化学结构研究

为研究树皮藻Ecklonia maxima岩藻聚糖硫酸酯的单糖组成及其化学结构,以产自南非的树皮藻为原料测定其基本成分,采用DEAE-Sepharose Fast Flow阴离子层析柱对树皮藻岩藻聚糖硫酸酯粗品进行分离纯化,通过柱前衍生高效液相色谱法、红外光谱法和核磁共振波谱法测定单糖组成和化学结构。结果表明:树皮藻干基中基本营养成分分别为灰分18.59%、蛋白质9.16%、脂肪0.74%;对树皮藻岩藻聚糖硫酸酯粗品进行纯化得到4个组分,分别命名为SPF1、SPF2、SPF3、SPF4,收集冻干各组分,检测各组分得率分别为18.19%、24.02%、5.61%、4.23%,硫酸根含量分别为12.07%、5.44%、15.58%、19.30%;4个组分主要由岩藻糖、半乳糖、鼠李糖、甘露糖和葡萄糖醛酸组成,还含有少量的葡萄糖和木糖,其中SPF3、SPF4主要由岩藻糖和半乳糖组成,岩藻糖含量分别为70.92%和86.20%,4个组分的红外光谱显示出典型的多糖吸收峰,SPF1、SPF2在13C核磁共振谱177×10-6附近均出现糖醛酸C6信号峰,SPF3、SPF4在18×10-6附近均出现信号峰,为α-L-吡喃岩藻糖C6信号峰。     

有机络合铜除藻剂稳定性的影响因素分析及提高其稳定性的方法探讨

对水处理药剂一有机络合铜除藻剂存放过程中产生的沉淀进行分析和对该沉淀产生的影响因素进行了探讨。实验证明：控制好产品体系中有机络合剂的残余量和产品体系的pH值，并对产品进行必要的处理后再包装贮运，能够有效延缓和控制有机络合铜除藻剂存放过程中产生的红黄色沉淀。     

氮、磷对青岛大扁藻生长的影响初探

本实验以按绿藻培养液配方出的基础培养液,设置2组N、P比例,通过室内光照培养箱培养青岛大扁藻,探讨氮、磷对青岛大扁藻生长的影响。结果显示:在25℃、5000lx的条件下,当氮磷源充足的情况下,青岛大扁藻生长的最佳氮磷比例为7.17:1;在氮磷营养盐条件受到限制的情况下,13.75∶1是青岛大扁藻生长较为理想的氮磷比。     

黑麦草野地瓜套种对重金属镉吸收的研究

为了研究野地瓜促进富集植物黑麦草吸收重金属镉的可能性,笔者通过盆栽试验的方式对比了不同处理中黑麦草地上部分重金属镉的含量。试验结果表明:套种野地瓜处理的黑麦草地上部分总镉含量为每盆5.6439×10~(-3)mg,而单独种植黑麦草处理组的黑麦草地上部分总镉含量为4.6164×10~(-3)mg,相比之下,增加了1.0275×10~(-3)mg,增加率为22.26%。野地瓜套种黑麦草能有效的促进黑麦草对重金属镉的吸收。本研究为促进富集植物对重金属的吸收提供了一种新的思路与途径。     

3种重金属联合对孔雀鱼肝脏抗氧化酶系统的影响

以孔雀鱼为受试生物,研究了3种重金属(Cu2+、Cd2+和Cr6+)联合毒性对孔雀鱼肝脏抗氧化酶系统的影响。结果表明:重金属对孔雀鱼肝脏3种抗氧化酶均有不同的影响,其中孔雀鱼肝脏CAT、GSH-PX活性在暴露2天后均被显著诱导,随着时间的延长酶活性逐渐降低,暴露8天后活性低于对照组。孔雀鱼肝脏SOD活性在暴露2天后呈现诱导效应,随着浓度的增大,诱导效应明显。在高浓度暴露条件下,暴露2天后SOD活性显著升高,但随着暴露时间的延长,SOD活性降低。     

镉对DNA甲基化的影响

镉是人类致癌物,目前普遍认为镉的致癌机制与表观遗传学有关。DNA甲基化是重要的表观遗传学修饰之一。本文从镉暴露对基因组总甲基化水平、甲基转移酶、基因表达的影响三个方面综述镉暴露对DNA甲基化的影响。     

温度和光照对引黄水库水特征藻种生长的影响

本文以某引黄水库中分离得到的铜绿微囊藻、四尾栅藻、顿脆杆藻三种特征性藻为研究对象,研究了不同的温度、光照条件对其生长状态的影响。结果表明,三种藻最佳生长温度为30℃、光照强度为6000 lx。对该类水库应加强水温和光照强度的实时监测,从而实现＂水华＂的间接预警。     

The distribution of cadmium between the marine alga Chlorella stigmatophora and sea water medium: Effect on algal growth

Distribution of dissolved cadmium between Chlorella stigmatophora and sea water medium—and possible effects of cadmium on the alga's growth—were investigated at cadmium concentrations between 1–10 mg 1⁻¹. Results show considerable cadmium uptake by Chlorella stigmatophora along the growth curve. No effect of cadmium uptake on growth expressed by number of cells was recorded but a considerable decrease in chlorophyll content per cell was established. A mathematical expression was developed for the distribution of cadmium between Chlorella stigmatophora and sea water medium.     

Phytoprotective influence of bacteria on growth and cadmium accumulation in the aquatic plant Lemna minor

Certain plants are known to accumulate heavy metals, and can be used in remediation of polluted soil or water. Plant-associated bacteria, especially those that are metal tolerant, may enhance the total amount of metal accumulated by the plant, but this process is still unclear. In this study, we investigated metal enhancement vs. exclusion by plants, and the phytoprotective role plant-associated bacteria might provide to plants exposed to heavy metal. We isolated cadmium-tolerant bacteria from the roots of the aquatic plant Lemna minor grown in heavy metal-polluted waters, and tested these isolates for tolerance to cadmium. The efficiency of plants to accumulate heavy metal from their surrounding environment was then tested by comparing L. minor plants grown with added metal tolerant bacteria to plants grown axenically to determine, whether bacteria associated with these plants increase metal accumulation in the plant.Unexpectedly, cadmium tolerance was not seen in all bacterial isolates that had been exposed to cadmium. Axenic plants accumulated slightly more cadmium than plants inoculated with bacterial isolates. Certain isolates promoted root growth, but overall, addition of bacterial strains did not enhance plant cadmium uptake, and in some cases, inhibited cadmium accumulation by plants. This suggests that bacteria serve a phytoprotective role in their relationship with Lemna minor, preventing toxic cadmium from entering plants.     

萱藻配子孤雌生殖丝状体的采苗及育苗研究

为研究萱藻Scytosiphon lomentaria的丝状体育苗,以大连沿海萱藻为材料,采用配子孤雌生殖方法,进行了丝状体的诱导及采苗、育苗研究。结果表明:单株种藻获得的配子经孤雌生殖形成的盘状体在20℃时生长最快,15℃时次之,10℃时最慢;盘状体直径达到100μm以上时开始形成丝状体,丝状体在20℃时形成的时间最短、数量最多、生长速度最快,15℃时次之,10℃时最差;将丝状体剥下经增殖后切碎采苗,在10℃时幼苗形成最快、形成率最高,15℃时次之,20℃时无幼苗形成;在10℃时,采苗后培养30 d幼苗长度达到(11.0±0.3)mm,移至海区栽培4个月后获得藻体长度为60 cm左右的萱藻成体。     

Effect of counterions on lanthanum biosorption by Sargassum polycystum

The effect of the presence of different anions on the biosorption of La(3+) (Lanthanum) using Sargassum polycystum Ca-loaded biomass was studied in this work. Different types of metal salts were used, such as nitrate, sulphate and chloride. The presence of the anion sulphate decreased the metal uptake for tested pH values of 3--5 when compared to the nitrate and chloride systems. The presence of chloride ions did not seem to interfere with the lanthanum removal. The speciation of lanthanum in solution could explain the differences obtained for the different systems and the Mineql+ program was used for the calculations. A monovalent complex with sulphate and lanthanum was formed that had lower apparent affinity towards the biomass compared to the free trivalent metal ion. The La uptake varied from 0.6 to 1.0 mmol g(-1). The Langmuir model was used to describe quantitatively the sorption isotherms. The addition of sulphuric acid for pH adjustment decreased the metal uptake from lanthanum sulphate solutions when compared to the nitric acid addition. The effect was more pronounced with sulphuric acid due to the formation of complexes.     

Role of dissolved and particulate cadmium in the accumulation of cadmium in cultured oysters (Crassostrea gigas)

Pacific oysters (Crassostrea gigas) collected on the coast of British Columbia, Canada have occasionally shown cadmium (Cd) concentrations at or above 2 microg g(-1) (wet weight), which has resulted in the loss of some international markets. This study investigated the source and transfer of Cd to oysters by focusing on the role of dissolved and particulate Cd in seawater. Parameters monitored for 1 year at two oyster farm sites on Vancouver Island included: oyster tissue mass and shell length, Cd in oysters, dissolved Cd, particulate Cd, temperature and salinity. Results show that dissolved Cd was the main source of Cd to the oysters and that Cd was mainly concentrated in the gut tissues. A seasonal trend was observed in Cd in oysters, in which levels were lowest during periods of higher temperatures. Results also indicate that the local oceanographic inputs and sediment diagenesis directly affect dissolved Cd and thereby influence the Cd levels in oysters. Particulate matter was not found to be a source of Cd in oysters, and was actually negatively correlated. This was likely due to the uptake of dissolved Cd by phytoplankton and the effect of phytoplankton on oyster tissue mass.     

Sorption and accumulation of cadmium in the sediment of the Tama River

Cadmium contents in the water and the sediment samples collected from the Tama River and several branches were measured. Cadmium (above 0.005mgl⁻¹) was detected in only four of the water samples, while the sediment samples showed cadmium content of 1.0–9.8 μg g⁻¹ dry sediment. Cadmium concentration in the sediments of the main stream was correlated against ignition loss of the samples and it was found that 1 g of ignition loss (organic matter) corresponded to 35 μg of cadmium.The batch adsorption experiment in the laboratory using an aqueous solution of cadmium for 14 sediment samples with a higher concentration of cadmium indicated that the amount adsorbed by the sediment is highly dependent on the ignition loss. The amount adsorbed on unit mass of ignition loss q_IL could be correlated by a Freundlich-type equilibrium relation as where C is the equilibrium concentration in the aqueous phase ranging between 7 × 10⁻³ and 10 mg l⁻¹, while k_IL and n are equilibrium constants.The adsorption rate measurement showed that the intraparticle diffusion coefficient of cadmium in the sediment was about 1.1 × 10⁻⁶ cm²s⁻¹, which is of a reasonable order of magnitude assuming the pore diffusion mechanism inside the particle.The results suggest that suspended solid particles of high organic content in flowing water contribute significantly to the transport of cadmium along the river.     

Selection and breeding of plant cultivars to minimize cadmium accumulation

Natural variation occurs in the uptake and distribution of essential and nonessential trace elements among crop species and among cultivars within species. Such variation can be responsible for trace element deficiencies and toxicities, which in turn can affect the quality of food. Plant breeding can be an important tool to both increase the concentration of desirable trace elements and reduce that of potentially harmful trace elements such as cadmium (Cd). Selection programs for a low-Cd content of various crops, including durum wheat, sunflower, rice and soybean have been established and low-Cd durum wheat cultivars and sunflower hybrids have been developed. In durum wheat (Triticum turgidum L. var durum), low-Cd concentration is controlled by a single dominant gene. The trait is highly heritable, and incorporation of the low-Cd allele can help to reduce the average grain Cd to levels below proposed international limits. The allele for low-Cd concentration does not appear to affect major economic traits and should not cause problems when incorporated into durum cultivars. The cost of Cd selection in a breeding program is initially large both in terms of Cd determination and reduced progress towards development of other economic traits, but declines as more breeding lines in the program carry the low-Cd trait and are utilized in new crosses. Production of low-Cd crop cultivars can be used as a tool to reduce the risk of movement of Cd into the human diet.     

山东地区现今地应力场特征与应力积累水平分析

 山东地区地质构造环境十分复杂,历史上曾多次发生中强地震及强震。为深入了解该地区现今构造应力场特征及区域地壳应力积累水平,基于优化处理后的181组地应力实测数据,采用回归分析法全面分析了该地区地应力量值随深度的分布特征,并依据地壳应力积累理论,探讨了区域应力积累水平和地壳稳定性。结果表明,该地区地应力状态主要以?H＞?h＞?v型和?H＞?v＞?h型为主,应力状态类型与深度有一定关系;3个主应力?H,?h和?v均随深度呈近似线性增加的关系,应力变化梯度值分别为0.024 2,0.018 0,0.025 8;3个侧压系数KH,Kh和Kav随深度呈近似双曲线分布,随着深度的增加分别向1.46,0.89,1.17趋近;水平差应力相对大小μd更接近于线性分布,随着深度的增加趋向于0.24;最大水平主应力优势方向整体表现为NWW-SEE向,但NEE-SWW向也占有较大比例,优势方位统计结果与世界应力图2016及板块间作用相吻合;沂沭断裂带西侧区域最大水平主应力优势方向整体呈NEE-SWW向,而其东侧区域整体呈NWW-SEE向。?m能较好地反映地壳应力积累能力,?m值主要集中在0.3～0.5,0.2～0.3范围内,该地区的应力积累水平整体上处于中低程度,地壳浅层处于相对稳定状态。逆断型应力状态的?m值主要集中在0.2～0.3范围内,应力积累水平以较低程度为主;走滑型应力状态的?m值主要集中在0.3～0.5范围内,应力积累水平以中等程度为主。     

Effect of shear stress and growth conditions on detachment and physical properties of biofilms

Detachment is one of the major processes determining the physical structure and microbial functionalities of biofilms. To predict detachment, it is necessary to take the mechanical properties of the biofilm and the effect of both hydrodynamic and growth conditions into account. In this work, experiments were conducted with biofilms developed under various shear stresses and with various substrate natures. In addition, two cases were considered in order to differentiate between the effect of hydrodynamic factors and growth factors: the biofilms were directly grown under the targeted shear stress (τ) condition or they were precultivated under very low shear stress (0.01 Pa) and then exposed to high shear stress in the range of 0.1-13 Pa. An exponential and asymptotic decrease of the biofilm thickness and mass with increasing τ was observed in both cases. On contrary density, expressed as the biofilm dry mass on a known substratum divided by the average thickness increased with τ. Denitrifying biofilms always showed greater thickness and density than oxic biofilms. These results showed the presence of a compact basal layer that resisted shear stresses as high as 13 Pa whatever the culture conditions. Above this basal layer, the cohesion was lower and depended on the shear stress applied during biofilm development. The application of shear stress to the biofilms resulted in both detachment and compression, but detachment prevailed for the upper part of the biofilms and compression prevailed for the basal layers. A model of biofilm structure underlying the stratified character of this aggregate is given in terms of density and cohesion.