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1.
Dissolved (dialysis in situ) and total concentrations ofCu, Zn, Cd and Al in eight mining polluted rivers in the Røros area, central Norway, were determinedby atomic absorption spectrometry (flame and graphite furnace) and compared to pH, Caconcentration and alkalinity through seasonal variations in river discharge. Totalconcentrations of the metals were highest during early spring flood and during summer andautumn rain episodes. Dissolved concentrations also increased as the spring floodproceeded, but small discharge peaks within this 2 month period as well as a considerableautumn flood episode appeared to lower rather than to raise the dissolved metal concentrations.Consequently the dissolved fractions of Zn, Cd and Al showed a significant negative correlationwith river discharge, and were low at the discharge peaks. Possibly high sediment concentrationsoccurring at high flood conditions more than counteracted desorption induced by pHdecrease, and led to decreased dissolved fractions through adsorption. Cu speciationon the other hand seemed to be more closely linked to pH. Alkalinity and Ca concentration,both assumed to protect aquatic life from metal pollution, were significantly lowerduring episodes with high Cu and Al total concentrations. 相似文献
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Water Flow, Trophic Depletion, and Benthic Macrofauna Impoverishment in a Submarine Cave from the Western Mediterranean 总被引：1，自引：0，他引：1
Mikel Zabala Tecla Riera Josep Maria Gili Manel Barange Agustin Lobo Josep Peñuelas 《Marine Ecology》1989,10(3):271-287
Abstract. Biotic zonation and severe impoverishment of benthic macrofauna are two of the most conspicuous features of submarine caves. The prevailing explanation assumes trophic depletion caused by reduction of water flow. However, no isolation of water was found in the studied Catalan submarine cave, even in the wall microlayer. Fluorescein diffusion was so fast that it was detectable everywhere in the cave already only a few minutes after the injection. The rate of dissolution of plaster spheres was even greater in the cave than in a nearby tunnel – without benthic macrofauna impoverishment – showing a considerable water flow. The oxygen concentration of water in dialysis bags placed at varying distances from the cave walls showed that no wall microlayer gradients were present.
Biochemical gradients did not indicate any decrease in food supply. Although photosynthetic pigment concentration generally decreased inside the cave, and although the gradients were not linear but formed different patterns throughout the cave, the BOD5 , the POM, the C:N ratio, the [3 H]-thymidine incorporation rate, and the ETS activity were higher in the inner part of the cave. There was an accumulation of detritic material and bacteria in the inner parts that constitute a plausible food supply for benthic macrofauna.
If neither water motion nor food supply can be invoked, research into the causes of zonation and disappearence of benthic macrofauna is proposed to be carried out on biotic interactions and behavioural processes. 相似文献
Biochemical gradients did not indicate any decrease in food supply. Although photosynthetic pigment concentration generally decreased inside the cave, and although the gradients were not linear but formed different patterns throughout the cave, the BOD
If neither water motion nor food supply can be invoked, research into the causes of zonation and disappearence of benthic macrofauna is proposed to be carried out on biotic interactions and behavioural processes. 相似文献
3.
在线渗析-离子色谱法测定土壤中有效氟 总被引：1，自引：1，他引：0
土壤样品经超声波超声静置,提取上清液,经渗析进入色谱柱,采用Metrohm A Supp 4-250阴离子交换柱,以1.8 mmol/L碳酸钠-1.7 mmol/L碳酸氢钠混合溶液作为流动相,用在线渗析技术与离子色谱法联用测定土壤中的有效氟。与常规方法相比,建立的方法操作简单,避免了繁琐的样品前处理。加标回收率为90.5%～95.7%,精密度(RSD,n=6)为1.60%。该方法具有高效、快速、灵敏等特点,能够用于环境土壤样品中有效氟的检测。 相似文献
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本研究在太湖梅梁湾采集沉积柱,采用一种自制的毫米级柱状沉积物自动垂向分层切割装置对表层50 mm沉积物进行垂向切割(间隔2 mm),结合高通量测序技术分析沉积物中细菌群落的毫米级垂向分布;同时采用毫米级高分辨透析技术和薄膜扩散梯度技术(DGT)分析溶解态和DGT可获取态铵态氮(NH4+-N)、硝态氮(NO3--N)、Fe、P的垂向分布特征。结果显示,沉积物中细菌群落与溶解态和DGT可获取态氮铁磷浓度在垂向上呈现显著的异质性。细菌硝酸盐还原主要发生在-16～0 mm沉积物深度,这可能导致了溶解态和DGT可获取态NO3--N含量在该沉积物深度的明显减少。细菌铁还原主要分布在-32～-18 mm沉积物深度,细菌硫酸盐还原主要分布在-50～-34 mm的沉积物深度;细菌硫酸盐还原是导致沉积物溶解态和DGT可获取态铁磷浓度从-32 mm随沉积物的深度增加而显著增加的主要原因。本研究加深了对富营养化湖泊沉积物中细菌影响氮磷在垂向上迁移转化的认识。 相似文献
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河豚毒素(Tetrodotoxin, TTX)在镇静、镇痛、麻醉、戒毒等神经性疾病治疗方面效果显著且无致瘾性,因此具有极好的应用前景,但由于其从河豚体内提取的成本过高,所以难以大量推广应用。越来越多的证据表明TTX来源于河豚体内共生的微生物。我们从野生横纹东方鲀(Takifugu oblongus)肝脏中分离得到了一株产TTX较高的芽孢杆菌3G2(Bacillus sp. 3G2),通过ELISA和胶体金的方法检测到其发酵液TTX含量为35 ng/mL。将该菌株接种于专用透析培养器中,不断流加新鲜培养基实现连续培养,同时实现简化分离工艺,对发酵液进行小鼠生物活性检测、TTX试纸条检测,并通过河豚毒素抗体免疫共沉淀纯化得到TTX粗品后进行高效液相色谱鉴定均表明发酵液中含有TTX且含量较高。本研究通过筛选产TTX的优质菌株进一步了证实河豚毒素外源性假说,并初步验证了透析法生产河豚毒素的优越性,为后续商业应用提供实践性基础。 相似文献
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目的：研究健脾益气方通过调控间隙连接蛋白（Cx）43干预腹膜透析大鼠腹膜间皮细胞转分化的作用机制。方法：将75只大鼠随机分为5组,即空白组、模型组、中药高剂量组、中药低剂量组、西药组,除空白组大鼠外,其余各组均采用5/6肾切除联合腹腔注射4.25％腹透液复制慢性肾衰竭腹膜纤维化大鼠模型。造模成功后,中药高、低剂量组给予健脾益气方,西药组给予阿托伐他汀钙,模型组给予0.9%氯化钠注射液,空白组不做任何处理。每天灌胃1次,连续4周。干预后光镜观察各组大鼠腹膜结构变化,测量腹膜致密层厚度;免疫组化法及蛋白质印迹法检测Cx43、蛋白激酶B/哺乳动物雷帕霉素靶蛋白（AKt/mTOR）通路和腹膜间皮细胞转分化（EMT）标志蛋白表达。结果：各组大鼠腹膜厚度及Cx43、pAKt、pmTOR、α平滑肌肌动蛋白（α-SMA）、E-钙黏附蛋白（E-cadherin）阳性面积比,空白组与模型组比较,中药高、低剂量组及西药组与模型组比较,中药高剂量组与西药组、中药低剂量组比较,差异均有统计学意义（P<0.05）。各组大鼠腹膜组织Cx43、pAKt、pmTOR、α-SMA、E-cadherin蛋白表达,空白组与模型组比较,中药高剂量组与西药组比较,差异均有统计学意义（P<0.05）。结论：健脾益气方可能通过调控Cx43表达,干预Akt/mTOR信号通路介导的腹膜间皮细胞EMT进程,从而发挥保护腹膜间皮细胞、防治腹膜损伤的作用。 相似文献
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扩散是低渗透系数情况下溶质迁移的主要方式,目前尚没有测定高塌落度防渗墙填料扩散系数的试验方法。根据沥出试验原理,将处于流动状态的填料用半透膜包裹进行透析试验,通过有限圆柱中溶质迁移解析解对溶质迁移过程进行拟合求其扩散系数,探讨了试验和数据处理的相关问题,研究了膨润土含量和盐浴浓度对扩散系数的影响规律。结果表明,随拟合天数增加,填料中NaCl有效扩散系数减小,而误差增大;高塌落度填料中溶质迁移明显比压实土样中快,按拟合误差小于0.5%作为试验数据取舍依据,这一误差要求实际上是对溶质迁移以扩散为主导这一条件的量化,保证了采用纯扩散解析解进行数据拟合的合理性;扩散系数随填料中膨润土含量增加而减小,随盐浴浓度增加而减小,但在试验范围内数值变化不大,透析试验是快速测定防渗墙填料中溶质有效扩散系数的可行方法。 相似文献
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采用透析的方法,研究了硫酸盐还原菌(SRB)及不同分子量(0~200、200~2 000、2 000~10 000)代谢产物与石膏接触时对其还原分解的影响。实验结果表明,SRB代谢产生了更多的碱性物质,导致体系pH值明显上升;随着SRB及其代谢产物与石膏的接触作用逐渐增强,石膏的还原分解能力逐渐提高;SRB及其代谢产物可以诱导形成具有良好结晶形态的方解石和无定形态碳酸盐沉淀;代谢产物除可促进石膏还原分解外,一定条件下也可抑制石膏溶解。研究结果表明,SRB及其代谢物与石膏的接触作用对其还原分解有一定的影响,影响机制主要为络合作用和营造pH值、HCO-3浓度不同于溶液的SRB-石膏界面微环境。 相似文献
10.
Size fractionation of ~40 major and trace elements (TE) in peat soil solutions from the Tverskaya region (Russia) has been
studied using frontal filtration and ultrafiltration through a progressively decreasing pore size (5, 2.5, 0.22 μm, 100, 10,
5, and 1 kD) and in situ dialysis through 6–8 and 1 kD membranes with subsequent analysis by ICP-MS. In (ultra) filter-passed permeates and dialysates
of soil solutions, Fe, Al, and organic carbon (OC) are well correlated, indicating the presence of mixed organo-mineral colloids.
All major anions and silica are present in “dissolved” forms passed through 1 kD membrane. According to their behavior during
filtration and dialysis and association with mineral or organic components, three groups of elements can be distinguished:
(i) species that are weakly affected by size separation operations and largely (>50–80%) present in the form of dissolved
inorganic species (Ca, Mg, Li, Na, K, Sr, Ba, Rb, Cs, As, Mn) with some proportion of small (1–10 kD) organic complexes (Ca,
Mg, Sr, Ba), (ii) biologically essential elements (Co, Ni, Zn, Cu, Cd) mainly present in the fraction smaller than 1 kD and
known to form strong organic complexes with fulvic acids, and, (iii) elements strongly associated with aluminum, iron and
OC in all ultrafiltrates and dialysates with 30–50% being concentrated in large (>10 kD) colloids (Ga, Y, REEs, Pb, Cd, V,
Nb, Sn, Ti, Zr, Hf, Th, U). For most trace metals, the proportion in the colloidal fraction correlates with their first hydrolysis
constant. This implies a strong control of negatively charged oxygen donors present in inorganic/organic colloids on TE distribution
between aqueous solution and colloid particles. It is suggested that these colloids are formed during plant uptake of Al,
Fe, and TE from mineral matrix of deep soil horizons and their subsequent release in surface horizons after litter degradation
and oxygenation on redox or acid/base fronts. Dissolved organic matter stabilizes Al/Fe colloids and thus enhances trace elements
transport in soil solutions. 相似文献