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1.
利用Playle等设计的装置研究了不同pH条件及不同的铜暴露水平下鲤鳃部微环境pH值和粘液分泌量的变化,在此基础上用化学平衡计算方法探讨鱼鳃微环境中铜形态的变化。结果表明,在特定的pH和铜浓度范围内,鱼鳃微环境平衡pH略低于7,鱼鳃粘液分泌量随铜暴露水平提高而增加,与此同时,虽然CO2分泌量有所增加,没有观察到微环境pH随铜暴露量的变化。pH的升高,导致水相优势的游离态铜让位给羟基络合铜,粘液络合态铜的分额逐渭降低,但不会改变其络合当量与条件稳定络合常数。由于鱼鳃微环境对pH改变的调节作用,铜的形态分布变化幅度低于外部环境。  相似文献   

2.
不同条件下鲤鱼鳃部对高岭土颗粒吸附态铜的吸收   总被引:2,自引:0,他引:2  
龙爱民  潘波  徐福留  李本纲  曹军  陶澍 《生态学报》2002,22(10):1640-1644
在水相溶解态铜浓度和高岭土吸附态铜浓度保持不变,pH和高岭土粒径不同条件下,研究了鲤鱼鱼鳃对铜的吸收。结果表明在本研究范围内,吸附态铜的存在增加了鱼鳃吸收。鳃对铜的吸收随pH增加而递增,随高岭土粒径减少而递增。利用MINTEQA2软件分析了不同实验条件下鱼鳃微环境中铜的形态分布特征,对吸附态铜可能的生物有效性机制进行了说明。  相似文献   

3.
鱼体(去鳃)和鱼鳃对不同形态铜的积累特征   总被引:9,自引:0,他引:9  
梁涛  陶澍  林健枝 《生态学报》1999,19(5):763-766
在实验室条件下研究实验鱼Paracheirodon对人工河水中不同形态的积累特征,对比了鱼体(去鳃)和鱼鳃对铜吸收量的差异,并探讨了鱼对铜的吸收机理。研究结果表明,实验鱼鳃部和体内铜积累量均随水相游离铜浓度增高,暴露时间增长而增加,但鳃部积累浓度较鱼体其余部分高一个数量级,其从水相富集铜的速率显著高于鱼体。  相似文献   

4.
酸性水和投加铝、钙对鲢鱼早期发育和鳃超微结构的影响   总被引:4,自引:1,他引:3  
在实验室条件下,研究了酸性水和投加铝、钙对鲢鱼胚胎孵化和鱼苗存活以及幼鱼鳃超微结构的影响。pH4.0引起所有胚胎在24小时内死亡,暴露于pH4.5—6.0的胚胎孵化率和暴露于pH4.0—6.0的5—15日龄鱼苗存活率随pH值上升而增高。投加0.5mg Al~(3+)/L使在酸性pH暴露条件下的胚胎孵化率和鱼苗存活率进一步降低。投加3.0mg Ca~(2+)/L可显著提高暴露于pH4.5和5.0的胚胎孵化率;投加2.0mg Ca~(2+)/L可在一定程度上提高暴露于pH4.5和5.0的鱼苗存活率。幼苗经pH4.5暴露8小时后出现严重的鳃超微结构损害;投加1.0mg Al~(3+)/L使鳃结构损害加剧;投加5.0mg Ca~(2+)/L可明显缓解酸性水对鳃的损害。  相似文献   

5.
在实验室条件下,研究了酸性水和投加铝、钙对鲢鱼胚胎孵化和鱼苗存活以及幼鱼鳃超微结构的影响。pH4.0引起所有胚胎在24小时内死亡,暴露于pH4.5-6.0的胚胎孵化率和暴露于pH4.0-6.0的5-15日龄鱼苗存活率随pH值上升而增高。投加0.5mgAl3+/L使在酸性pH暴露条件下的胚胎孵化率和鱼苗存活率进一步降低。投加3.0mgCa2+/L可显著提高暴露于pH4.5和5.0的胚胎孵化率;投加2.0mgCa2+/L可在一定程度上提高暴露于pH4.5和5.0的鱼苗存活率。幼苗经pH4.5暴露8小时后出现严重的鳃超微结构损害;投加1.0mgAl3+/L使鳃结构损害加剧;投加5.0mgCa2+/L可明显缓解酸性水对鳃的损害。  相似文献   

6.
金鱼(Carassius auratus)鳃对颗粒吸附态铅的吸收   总被引:8,自引:2,他引:6  
研究了金鱼(Carassius auratus)鳃在悬浮水铝矿吸附态Pb暴露实验中对Pb吸收过程,结果表明,在保持水中游离态Pb浓度不变(0.1mg.L^-1)、吸附态Pb浓度增加的条件下,鳃中Pb,Al浓度均随暴露浓度增加而增加,血液中Pb浓度随鳃中Pb浓度的增加率(直线斜率0.171)低于溶解态Pb、暴露实验的增加率(直线斜率0.343),附着鳃上的部分Pb未移转至血液中,鳃中Pb/Al比较水  相似文献   

7.
海洋酸化条件下铜、镉对日本虎斑猛水蚤的急性毒性效应   总被引:1,自引:0,他引:1  
韦晓慧  慕芳红  孙艳桃  曹志泉 《生态学报》2014,34(14):3879-3884
以日本虎斑猛水蚤(Tigriopus japonicus)为试验生物,采用高纯度CO2和空气的混合气体调配试验所需酸化海水(pH值7.70、7.30、6.50),研究不同海水酸化条件下铜、镉对海洋生物的急性毒性效应。结果表明:单一CO2酸化海水对日本虎斑猛水蚤存活的影响不显著;海水酸化对铜和镉急性毒性的影响效应有差异。铜在低pH值(6.5)时对日本虎斑猛水蚤的毒性最强,96h LC50浓度为0.64 mg/L,明显低于pH值为8.0、7.7、7.3对日本虎斑猛水蚤的96h LC50浓度,其分别为1.98,1.19,1.05 mg/L,随pH值下降,96h LC50下降了近3倍。海水酸化使镉的96h LC50略呈下降趋势,但对其急性毒性影响效应并不显著;pH值为7.7和7.3时,铜的安全浓度分别为11.9、10.5μg/L,接近于中国海水二类水质标准。本研究表明随着海洋酸化的进程我国近海水域将面临铜污染加剧的威胁。  相似文献   

8.
不同土地利用方式土下岩溶溶蚀速率及影响因素   总被引:8,自引:0,他引:8  
以重庆中梁山为例,通过野外埋放标准溶蚀试片、土壤CO2收集装置和进行亮蓝染色示踪试验,测试不同土地利用方式下不同土层碳酸盐岩溶蚀速率、土壤CO2浓度、土壤溶解性有机碳(DOC)含量及土壤含水量、土壤pH值和孔L隙度等性质,探讨不同土地利用方式土下溶蚀速率差异及其影响因素.结果表明不同土地利用方式对土壤理化性质产生影响,形成特定的岩溶微环境,进而影响土下不同层次的岩溶作用:土壤CO2浓度是影响林地和草地旱季土下溶蚀速率的重要驱动力;土壤含水量和供水能力是影响旱季不同土地利用方式溶蚀速率的关键因素;菜地产生的酸性物质较多,土壤pH值最低,其平均溶蚀速率高于林地;土壤DOC随水下渗迁移性强,是林地土下50 cm处溶蚀速率高于土下20 cm处的原因之一.该文为西南岩溶区土下岩溶机理、岩溶碳汇提供理论依据和数据参考.  相似文献   

9.
金鱼对铅和镉的吸收蓄积   总被引:53,自引:1,他引:52  
研究了铅、镉暴露实验中金鱼不同器官经有收积累铅、镉的过程及蓄积量。结合到金鱼鳃上的铅、镉可用Langmuir吸附等温式描述。最大结合容量Bmax为:铅0.9424mmol/kg干重;镉17662μmol/kg条件稳定常数logK为:铅7.80;镉6.38。Hill结合特征常数为:铅1.012;镉1.175,表明金鱼鳃上仅有一种类型的Pb^2 或Cd^2 结合位点。鳃中铅、镉含量与血液含量以及血液铅、镉含量与肾、肝中的含量呈正相关关系。肾脏对铅、镉的蓄积量高于其他器官。  相似文献   

10.
赤潮藻中肋骨条藻的光合作用对海水pH和N变化的响应   总被引:4,自引:0,他引:4  
为探讨赤潮发生时中肋骨条藻 (Skeletonemacoatatum)的光合作用生理变化 ,研究了不同无机氮 (N)水平上 ,海水pH值升高对其胞外碳酸酐酶 (CA)和光合生理特性的影响。海水pH从 8.2升至 8.7时 ,中肋骨条藻胞外CA被诱导 ,细胞对无机碳的亲和力 (1/Km)提高 ;在pH8 7时 ,高N条件下的胞外CA活性是低N条件下的 3倍 ,1/Km 值也提高了 80 %。单位叶绿素a的最大净光合能力 (Pam)在不同pH和N水平上没有显著差异 ;但单位细胞的最大净光合能力 (Pcm)提高了 10 0 %。这些结果表明 ,赤潮发生时 ,中肋骨条藻通过启动无机碳浓缩机制 (CCM) ,提高细胞对无机碳利用效率 ,使其在低CO2 (高pH)环境下维持光合机构正常运行 ;充足的N源有利于提高CCM的效率 ,从而提高CO2 环境下的光合固碳能力。  相似文献   

11.
In addition to metabolic CO2 production and gill ventilatory flow rate, expired water PCO2 is very dependent on water acid-base balance in a complex way. This is particularly true in carbonated waters at low ambient PCO2 and high pH, where CO2 excreted in the gill water may be buffered by carbonate ions, leading to an increased CO2 capacitance coefficient. The higher the carbonate alkalinity (CA) and the lower the inspired PCO2 (i.e., the higher the inspired water pH), the stronger the carbonate buffering and the smaller the increase of PCO2 in the gill water during respiratory CO2 exchanges. As a consequence, as shown by a number of reported data, increasing the CA leads to blood hypocapnia and respiratory alkalosis at constant low, but not at high, inspired PCO2. In the low range of inspired PCO2, internal PCO2 becomes very sensitive to even small changes of water PCO2, which may explain at least in part the large variability of reported blood PCO2 values in gill breathers. Water CA also influences the amplitude of respiratory acid-base disturbances caused by changes of the gill ventilatory flow rate. Carbonate buffering of excreted CO2 and thus dependence of blood PCO2 on water alkalinity requires catalysis of CO2 hydration by carbonic anhydrase, that must be available from the water side of the gill epithelium.  相似文献   

12.
Rainbow trout were fitted with latex masks for the measurement of ventilatory flow rate (V?w) and with opercular catheters for sampling expired water from close to the branchial surface. Fish were exposed for 6 h to pH 5.1, 4.7 or 4.1 in the presence (138 μg l 1) or nominal absence (1 μg 1–1) of Al. Inspired and expired Al concentrations and water pH were measured via the opercular catheters. Gills were sampled for accumulated Al at the end of the experiments. V?w increased during Al exposures at all three pHs. However, in the absence of Al, V?w increased only at pH 4.1. Aluminium extraction from the water and Al accumulation on the gills were highest at inspired pH 5.1 and lowest at pH 4.1, and correlated well with expired pH, which was 0.2–0.7 pH units higher than inspired pH. Gill Al accumulations amounted to only about one-tenth of deposition calculated from Al extraction from the water and V?w, and gill Al was tightly bound to the branchial surface. Calculations of Al solubility, oversaturation, and species composition were made using measured expired pH values, and were compared with Al extraction from the water and measured gill Al concentrations. In general, these analyses indicated that reduced Al solubility near the gills is a reasonable explanation of Al extraction from the water, and that Al(OH)2+ and Al(OH)3° are the Al species most likely to interact initially at the gills. It is suggested that mucus sloughing removes most precipitated Al, and that only the charged form persists, bound to structural elements on the gill surface. A model incorporating these results, and pH changes in the fish gill micro-environment in general, is presented to explain previously-reported ionoregulatory and respiratory effects of Al.  相似文献   

13.
The accuracy of a computerized metabolic system, using inspiratory and expiratory methods of measuring ventilation, was assessed in eight male subjects. Gas exchange was measured at rest and during five stages on a cycle ergometer. Pneumotachometers were placed on the inspired and expired side to measure inspired (VI) and expired ventilation (VE). The devices were connected to two systems sampling expired O(2) and CO(2) from a single mixing chamber. Simultaneously, the criterion (Douglas bag, or DB) method assessed VE and fractions of O(2) and CO(2) in expired gas (FE(O(2)) and FE(CO(2))) for subsequent calculation of O(2) uptake (VO(2)), CO(2) production (VCO(2)), and respiratory exchange ratio. Both systems accurately measured metabolic variables over a wide range of intensities. Though differences were found between the DB and computerized systems for FE(O(2)) (both inspired and expired systems), FE(CO(2)) (expired system only), and VO(2) (inspired system only), the differences were extremely small (FE(O(2)) = 0.0004, FE(CO(2)) = -0.0003, VO(2) = -0.018 l/min). Thus a computerized system, using inspiratory or expiratory configurations, permits extremely precise measurements to be made in a less time-consuming manner than the DB technique.  相似文献   

14.
Ventilatory responses of crabs Carcinus maenas (L.) to changes in ambient oxygen and carbon dioxide were studied in field and laboratory experiments, over a range of PwO2 and Pwco2 conditions encompassing natural variations observed in intertidal rock-pools. Ventilatory activity was assessed by recording gill chamber hydrostatic pressure and estimating the specific ventilation, Vw/MO2, the reciprocal of the difference of oxygen concentrations in inspired and expired waters.

Variations in ambient oxygenation always induced large changes of ventilatory activity, hyperventilation in hypoxia, hypoventilation in hyperoxia. Conversely, PwCO2 changes either at constant PO2 or in combination with different PO2 values (hypoxic hypercapnia or hyperoxic hypocapnia) led only to small or even non-significant ventilatory responses. In the field, strong hyperventilation developed during tidal exposure at night, when the pool water became hypoxic and hypercapnic, whereas during the day the animals hypoventilated in progressively more hyperoxic and hypocapnic conditions.

Thus, in a typical intertidal animal such as C. maenas, the only ventilatory stimulus of ecological significance appears to be the ambient water oxygenation.  相似文献   


15.
Rainbow trout (Salmo gairdneri) were exposed to pH 5.0-5.1, 6.6 and/or calcium-enriched freshwater for 14 days. Hematocrit, gill Ca2+-ATPase enzyme activities, gill osmotic water inflow, plasma calcium and osmolarity were measured. No significant changes in plasma calcium ion levels were found. The typical increase in hematocrit usually associated with exposure of fish to acidified water was not found in the present study and is discussed. Plasma osmolarity decreased in fish exposed to calcium-enriched freshwater (60 mg Ca2+ X 1(-1) ) in comparison to fish exposed to control freshwater conditions (2 mg Ca2+ X 1(1) ), irrespective of the pH level. Gill Ca2+-ATPase enzyme activities were measured for both low affinity (3 mM Ca2+) and high affinity (100 microM) activity. Exposure of rainbow trout to low pH (pH 5.0-5.1) did not affect the specific activity of Ca2+-ATPase enzyme. However, low affinity Ca2+-ATPase activity in fish exposed to calcium-enriched freshwater did show a significant reduction. The increase in gill osmotic water permeability in fish exposed to calcium-enriched freshwater is interpreted as a result of the increase in osmolarity of the ambient media.  相似文献   

16.
The gill is both a site of gas transfer and an important location of chemoreception or gas sensing in fish. While often considered separately, these two processes are clearly intricately related because the gases that are transferred between the ventilatory water and blood at the gill are simultaneously sensed by chemoreceptors on, and within, the gill. Modulation of chemoreceptor discharge in response to changes in O(2) and CO(2) levels, in turn, is believed to initiate a series of coordinated cardiorespiratory reflexes aimed at optimising branchial gas transfer. The past decade has yielded numerous advances in terms of our understanding of gas transfer and gas sensing at the fish gill, particularly concerning the transfer and sensing of carbon dioxide. In addition, recent research has moved from striving to construct a single model that covers all fish species, to recognition of the considerable inter-specific variation that exists with respect to the mechanics of gas transfer and the cardiorespiratory responses of fish to changes in O(2) and CO(2) levels. The following review attempts to integrate gas transfer and gas sensing at the fish gill by exploring recent advances in these areas.  相似文献   

17.
Summary Rainbow trout (Salmo gairdneri) were exposed to acidic soft water (pHin4.2–6.3) in the presence (93 g·l–1) or absence of Al. Fish were fitted with latex masks and opercular catheters to measure ventilation , pH changes at the gills, O2 consumption , ammonia excretion , and Al extraction. During 2–3-h exposures, was generally higher in Al-exposed fish over the pHin range 4.7–6.3. Alkalinization of expired water was about 0.3 pH units less in Al-exposed fish than in acid-only exposed fish at pHin 4.5–5.2, an effect attributable to both increased and to buffering by Al. During 44-h exposures to pHin 5.2 and 4.8 plus Al, increased greatly and expired water pH (pHex) decreased with time. There was a small increase in over 44 h at pH 4.4 plus Al, and no changes in pHex. In contrast, during 44-h exposures to pH 5.2, 4.8, and 4.4 in the absence of Al, such changes were much smaller or absent. During both short- and longerterm exposures, measured Al accumulation on the gills was only 5–18% of that calculated from cumulative Al extraction from the water, suggesting considerable sloughing of Al. In free-swimming trout, gill Al accumulation was greatest during exposure (2h) to Al at pH 5.2, lower at pH 4.8, and least at pH 4.4 and 4.0. Our results suggest that Al deposition occurs at the gills, causing respiratory and ionoregulatory toxicity, because the pH in the branchial micro-environment is raised above that in the acidic inspired soft water. Higher pH at fish gills may result in Al precipitation due to loss of solubility, or Al accumulation because of shifts in Al species to Al-hydroxide forms which more readily adsorb to the gills.Abbreviations pH ex expired pH - pH in inspired pH  相似文献   

18.
That ventilation in fish is driven by O2 has long been accepted. The O2 ventilatory drive reflects the much lower capacitance of water for O2 than for CO2, and is mediated by O2 receptors that are distributed throughout the gill arches and that monitor both internal and external O2 levels. In recent years, however, evidence has amassed in support of the existence of a ventilatory drive in fish that is keyed to CO2 and/or pH. While ventilatory responses to CO2/pH may be mediated in part by the O2 drive through CO2/pH-induced changes in blood O2 status, CO2/pH also appear to stimulate ventilation directly. The receptors involved in this pathway are as yet unknown, but the experimental evidence available to date supports the involvement of branchial CO2-sensitive chemoreceptors with an external orientation. Internally-oriented CO2-sensitive chemoreceptors may also be involved, although evidence on this point remains equivocal. In the present paper, the evidence for a CO2/pH-keyed ventilatory drive in fish will be reviewed.  相似文献   

19.
Summary Soft water of low buffer capacity was drawn from near the branchial surface of rainbow trout (Salmo gairdneri) at 15°C, using opercular catheters, to determine pH changes in water passing over the gills. Latex masks allowed measurement of ventilation volume, and concentrations of carbon dioxide, oxygen, ammonia, and titratable base in expired water were compared to concentrations in inspired water. Water passing over the gills was more basic than inspired water if the inspired water was pH 4–6 (maximum increase: +0.7 pH units near pH 5). Expired water was more acidic than inspired water if the inspired water was pH 6–10 (maximum decrease: –1.7 pH units near pH 9). Ventilation volume (0.37 l·kg–1·min–1) and oxygen consumption (1.7 mmol·kg–1·h–1) were constant in the pH range 4.6–10.1, but both increased by 1.6–2.4× near pH 4. Carbon dioxide transfer near the gills was about 100 M, ammonia transfer about 15 M, and titratable base added at the gills was about 30 M. A theoretical model using CO2, titratable base, and ammonia added at the gills, the titration characteristics of the defined soft water medium, and aquatic equilibria for CO2 and ammonia, adequately explained the experimentally observed changes in pH near trout gills. Our observations and predictive model indicate that any gill contaminant whose toxicity varies with pH may be more or less toxic at the gills than predicted from bulk water chemistry alone.Abbreviations pH ex expired pH - pH in inspired pH  相似文献   

20.
The influence of ambient and arterial PCO2 on miduterine arterial flow of pregnant sheep acutely exposed to hot environments was investigated. Five mixed-breed ewes between 120 and 130 days of gestation were subjected to hot environments (increasing from thermoneutral 23 to 40 degrees C), and arterial blood pH, PCO2, and PO2 were determined at 5-min intervals. Respiratory rate, heart rate, rectal temperature, blood pressure, and miduterine arterial flow were continuously monitored prior to and during elevation of ambient air temperature. When miduterine arterial flow had decreased to 50% of thermoneutral control levels, ambient air CO2 was increased to 2.5%. Elevated ambient inspired CO2 caused a reversal in arterial pH and PCO2 to near thermoneutral levels. Miduterine arterial flow increased to 77% of the control levels following the elevated ambient PCO2 period. Respiratory rate also decreased when ambient CO2 was increased but remained 136% greater than the thermoneutral control level. All other parameters remained near their heat stress (40 degrees C) level during the elevation of ambient CO2. These data indicate that heat-stress-induced depression of miduterine arterial flow is vasoactively regulated, and cause-effect related to both arterial pH and PCO2, and thermoregulatory shunting of blood to heat-dissipating surfaces.  相似文献   

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