氨氮对鱼类的危害

    高亚峰+孙洪杰

    摘 要:氨氮是水产养殖中需要密切关注的水质指标。氨氮对鱼类的毒害作用主要归因于其所包含的非离子氨(NH3-N)的毒性。研究表明:NH3-N能够影响鱼类的生长、渗透压的平衡、代谢活动等,并能对鱼类造成一定的损伤。本文就NH3-N的毒性做了详细阐述。

    关键词:非离子氨;离子氨;鱼类;毒性

    氨氮是水产养殖环境中的一个环境污染的指标。研究表明,高浓度氨氮能够严重影响水生动物的正常生活。随着水产养殖业集约化、规模化的迅速发展,使得水产养殖业中氨氮污染的问题变得日益严重。因为随着养殖规模的扩大,大大降低了水体中水生生物的多样性,减弱了池塘中的能量流动,导致投入的饵料、粪便及各种生物的尸体等含蛋白质的物质不能及时分解。当池塘中所含的氨氮总量多余消散量时,随着时间的迁移,池塘中氨氮的含量逐渐累积,达到一定程度后,就会对水生生物产生毒害作用,造成较大的危害。

    1 氨氮的存在形式

    作为水生生物的“头号隐形杀手”,氨氮主要以两种形式存在于水体中:非离子氨(NH3-N)和离子氨(NH4+)。二者在水体中存在一定的平衡:NH4+OH-NH3·H2ONH3+H2O[1]。 NH3-N和NH4+的相对浓度与pH值和温度有密切的关系。通过Emerson, Russo, Lund and Thurston [1]的实验研究发现:NH3=[NH3+NH4+]1+10(pKa-pH):pKa=0.090 18+2 729.92/T, (T in Kelvin=273+T℃),在pH值和温度一定的情况下,二者能够按照一定比例而共存。通过近年来对氨氮毒性的研究可知:氨氮对水生动物的毒性,主要是它所包含的NH3-N起作用。NH3-N是具有毒性的,然而NH4+对水生动物的毒性很小,甚至可以忽略不计[2]。但是研究表明,NH4+对亚硝化单胞菌(Nitrosomonas)和硝化细菌(Nitrobacter)有一定的毒性,能够抑制硝化反应的进行,进而导致水体中NH3-N浓度的增加,增强了氨氮对水生动物的毒性[3]。

    2 氨氮对鱼类的影响

    由于氨氮是制约水产养殖业发展的重要因素,为了更好地了解氨氮的毒性,学者们对于NH3-N对鱼的毒性进行了深入的研究。大量的研究表明:NH3-N能够影响鱼类正常的生长。其中一些学者认为,NH3-N能够对鱼类的正常生活形成胁迫作用,将会抑制它们的生长[4-5]。Foss, et al.[6]也证实了高浓度的NH3-N能够抑制比目鱼(Scophthalmus maximus)的生长,高浓度的NH3-N对鱼有胁迫作用,抑制了鱼的摄食,因此生长受到限制。然而也有一些学者认为NH3-N能够促进鱼的生长[7-8],Sun, et al.[9]通过实验也证实了低浓度的NH3-N促进鳙鱼(Hypophthalmythys nobilis)仔鱼的生长。并推测这可能是因为仔鱼机体能够充分利用外界中NH3-N提供的氮源,考虑到NH3-N对鱼体重影响的结论不一致,可能是因为NH3-N对不同种类、不同时期的鱼类的影响不同。此外,NH3-N还会对鱼类产生其他影响。抗氧化系统,是鱼体抵御环境胁迫的第一道屏障,能够及时准确地反映出机体受到的损害[10]。抗氧化酶类的存在对鱼类适应外界环境起到重要作用,研究表明:胚胎及孵化初期的仔鱼就已经形成了抗氧化系统,具备了清除体内氧化自由基和过氧化物的能力[10-11]。抗氧化酶,作为抗氧化系统的重要组成部分,对机体抵御环境胁迫有很重要的作用。Yang, et al. [12]研究指出:长期暴露在NH3-N(安全浓度)环境下,能够影响鲫鱼(Carassius carassius)的抗氧化酶类(CAT和SOD)的活性和抗氧化物质(GSH)的含量。Hegazi, et al.[13]也通过实验发现:长期暴露NH3-N能够影响罗非鱼(Oreochromis niloticus)的抗氧化酶类。在NH3-N影响鱼体的抗氧化系统的同时,降低了机体的免疫力,进而导致机体更易感染一些细菌性或寄生性疾病。这是因为NH3-N能够对机体造成氧化应激,破坏机体的抗氧化系统,进而降低机体的免疫能力[12,14]。除此之外,NH3-N还会对鱼类的ATP产生影响。有研究指出:NH3-N能够抑制ATP的产生,并能耗尽脑部的ATP。因为氨氮能够通过激活NMDA 受体,进而减少了对Na+、K+磷酰化过程中起主要作用的蛋白激酶C[15-17]。另外,也有研究证实了,NH3-N能够影响机体的渗透压平衡,进而对其肝脏和肾脏造成紊乱[18]。并可以影响鱼体内的糖酵解,抑制克氏循环并减弱了血液的携氧能力。随着NH3-N进入到鱼体内,组织中氨浓度的提高抑制了机体的蛋白质分解和氨基酸的水解来降低体内氨的含量。与此同时磷酸果糖激酶被激活,进而影响糖酵解过程。NH3-N对糖酵解过程的影响而导致败血症的产生,进而对血液的携氧能力产生影响[19-20]。NH3-N除了影响鱼类体内的正常代谢、生化反应等,还对其生理造成损伤。NH3-N可以诱导鱼类的许多组织发生病变[21-22]。Benli, et al.[23]通过慢性(6周)暴露实验发现,NH3-N能够诱导罗非鱼(Oreochromis niloticus L.)的鳃组织充血、肝组织肿胀、诱变肾炎等病变。Spencer, et al.[24]通过亚急性实验也证实了,21天的NH3-N暴露能够导致杜父鱼(Cottus cognatus)的鳃组织发生病变。Miron, et al.[25]通过急性试验表明:短时间(96 h)的NH3-N暴露能够促使鲶鱼(Rhamdia quelen)的鳃组织发生病变。这表明NH3-N对鱼类的危害性很大,能够影响机体内的抗氧化系统的平衡,并在短时间内能够诱导机体发生病变。

    除此之外,研究还发现:NH3-N还具有神经毒性[26-27]。NH3-N进入血液中转换成离子氨,NH4+能够通过替代K+激活NMDA谷氨酸受体,进而导致过多的Ca2+流失,最终导致神经细胞死亡[27]。

    综上所述,NH3-N能够对鱼类造成多种危害,究其原因可能是:NH3-N能够像O2、CO2一样通过鱼鳃的上皮细胞内的水蛋白通道进入到鱼体内,在血液中NH3-N被转化成离子氨,带电荷的NH4+影响了机体的渗透压平衡,又因为其所带的电荷影响机体内正常的生化反应,进而可以对机体造成生理上的影响。

    参考文献:

    [1] Emerson, K.; Russo, R. C.; Lund, R. E.; Thurston, R. V., Aqueous ammonia equilibrium calculations: effect of pH and temperature. J. Fish. Board Can. 1975, 32, (12), 2379-2383

    [2] Constable, M.; Charlton, M.; Jensen, F.; McDonald, K.; Craig, G.; Taylor, K. W., An ecological risk assessment of ammonia in the aquatic environment. Hum. Ecol. Risk Assess. 2003, 9, (2), 527-548

    [3] Anthonisen, A.; Loehr, R.; Prakasam, T.; Srinath, E., Inhibition of nitrification by ammonia and nitrous acid. J. Water Pollut. Control Fed. 1976, 48, (5), 835-852

    [4] Person-Le Ruyet, J.; Mahe, K.; Le Bayon, N.; Le Delliou, H., Effects of temperature on growth and metabolism in a Mediterranean population of European sea bass, Dicentrarchus labrax. Aquaculture 2004, 237, (1), 269-280

    [5] Foss, A.; Evensen, T. H.; Vollen, T.; ?iestad, V., Effects of chronic ammonia exposure on growth and food conversion efficiency in juvenile spotted wolffish. Aquaculture 2003, 228, (1), 215-224

    [6] Foss, A.; Imsland, A. K.; Roth, B.; Schram, E.; Stefansson, S. O., Interactive effects of oxygen saturation and ammonia on growth and blood physiology in juvenile turbot. Aquaculture 2007, 271, (1), 244-251

    [7] Wood, C. M., Dogmas and controversies in the handling of nitrogenous wastes: Is exogenous ammonia a growth stimulant in fish J. Exp. Biol. 2004, 207, (12), 2043-2054.

    [8] Foss, A.; Siikavuopio, S. I.; S?ther, B.-S.; Evensen, T. H., Effect of chronic ammonia exposure on growth in juvenile Atlantic cod. Aquaculture 2004, 237, (1), 179-189

    [9] Sun, H.; Lü, K.; Minter, E. J.; Chen, Y.; Yang, Z.; Montagnes, D. J., Combined effects of ammonia and microcystin on survival, growth, antioxidant responses, and lipid peroxidation of bighead carp Hypophthalmythys nobilis larvae. J. Hazard. Mater. 2012, 221, 213-219

    [10] Sun, H.; Yang, W.; Chen, Y.; Yang, Z., Effect of purified microcystin on oxidative stress of silver carp Hypophthalmichthys molitrix larvae under different ammonia concentrations. Biochem. Syst. Ecol. 2011, 39, (4), 536-543

    [11] Chen, Y.; Sun, H.; Yang, W.; Yang, Z., Incubation and oxidative stress of grass carp (Ctenopharyngodon idella) embryos exposed to different un-ionized ammonia levels. J. Freshwater Ecol. 2012, 27, (1), 143-150

    [12] Yang, W.; Sun, H.; Xiang, F.; Yang, Z.; Chen, Y., Response of juvenile crucian carp (Carassius auratus) to long-term ammonia exposure: feeding, growth, and antioxidant defenses. J. Freshwater Ecol. 2011, 26, (4), 563-570

    [13] Hegazi, M. M.; Attia, Z. I.; Ashour, O. A., Oxidative stress and antioxidant enzymes in liver and white muscle of Nile tilapia juveniles in chronic ammonia exposure. Aquat. Toxicol. 2010, 99, (2), 118-125

    [14] Yang, W.; Xiang, F.; Sun, H.; Chen, Y.; Minter, E.; Yang, Z., Changes in the selected hematological parameters and gill Na+/K+ ATPase activity of juvenile crucian carp Carassius auratus during elevated ammonia exposure and the post-exposure recovery. Biochem. Syst. Ecol. 2010, 38, (4), 557-562

    [15] Kosenko, E.; Kaminsky, Y.; Grau, E.; Mi?ana, M. D.; Marcaida, G.; Grisolía, S.; Felipo, V., Brain ATP depletion induced by acute ammonia intoxication in rats is mediated by activation of the NMDA receptor and Na+, K+‐ATPase. J. Neurochem. 1994, 63, (6), 2172-2178.

    [16] Kosenko, E.; Kaminsky, M.; Kaminsky, A.; Valencia, M.; Lee, L.; Hermenegildo, C.; Felipo, V., Superoxide production and antioxidant enzymes in ammonia intoxication in rats. Free Radical Res. 1997, 27, (6), 637-644

    [17] Hurvitz, A.; Bercovier, H.; Van run, J., Effect of ammonia on the survival and the immune response of rainbow trout (Oncorhynchus mykiss, Walbaum) vaccinated against Streptococcus iniae Fish Shellfish Immunol. 1997, 7, (1), 45-53

    [18] Eddy, F., Ammonia in estuaries and effects on fish. J. Fish Biol. 2005, 67, (6), 1495-1513

    [19] Sousa, R. J.; Meade, T. L., The influence of ammonia on the oxygen delivery system of coho salmon hemoglobin. Comp. Biochem. Phys. A 1977, 58, (1), 23-28.

    [20] Ip, Y.; Chew, S.; Randall, D., Ammonia toxicity, tolerance, and excretion. Fish Physiol. 2001, 20, 109-148

    [21] Schuwerack, P.-M.; Lewis, J.; Hoole, D.; Morley, N., Ammonia-induced cellular and immunological changes in juvenile Cyprinus carpio infected with the blood fluke Sanguinicola inermis. Parasitology 2001, 122, (03), 339-345

    [22] Vogelbein, W.; Shields, J.; Haas, L.; Reece, K.; Zwerner, D., Skin ulcers in estuarine fishes: a comparative pathological evaluation of wild and laboratory-exposed fish. Environ. health Persp. 2001, 109, (Suppl 5), 687

    [23] Benli, A. . K.; Kksal, G.; ?zkul, A., Sublethal ammonia exposure of Nile tilapia (Oreochromis niloticus L.): Effects on gill, liver and kidney histology. Chemosphere 2008, 72, (9), 1355-1358

    [24] Spencer, P.; Pollock, R.; Dubé, M., Effects of un-ionized ammonia on histological, endocrine, and whole organism endpoints in slimy sculpin (Cottus cognatus). Aquat. Toxicol. 2008, 90, (4), 300-309

    [25] Miron, D. d. S.; Moraes, B.; Becker, A. G.; Crestani, M.; Spanevello, R.; Loro, V. L.; Baldisserotto, B., Ammonia and pH effects on some metabolic parameters and gill histology of silver catfish, Rhamdia quelen (Heptapteridae). Aquaculture 2008, 277, (3), 192-196

    [26] Felipo, V.; Kosenko, E.; Mi?ana, M.-D.; Marcaida, G.; Grisolia, S., Molecular mechanism of acute ammonia toxicity and of its prevention by L-carnitine. In Hepatic Encephalopathy, Hyperammonemia, and Ammonia Toxicity, Springer: 1994; pp 65-77

    [27] Randall, D.; Tsui, T., Ammonia toxicity in fish. Mar. Pollut. Bull. 2002, 45, (1), 17-23

    [13] Hegazi, M. M.; Attia, Z. I.; Ashour, O. A., Oxidative stress and antioxidant enzymes in liver and white muscle of Nile tilapia juveniles in chronic ammonia exposure. Aquat. Toxicol. 2010, 99, (2), 118-125

    [14] Yang, W.; Xiang, F.; Sun, H.; Chen, Y.; Minter, E.; Yang, Z., Changes in the selected hematological parameters and gill Na+/K+ ATPase activity of juvenile crucian carp Carassius auratus during elevated ammonia exposure and the post-exposure recovery. Biochem. Syst. Ecol. 2010, 38, (4), 557-562

    [15] Kosenko, E.; Kaminsky, Y.; Grau, E.; Mi?ana, M. D.; Marcaida, G.; Grisolía, S.; Felipo, V., Brain ATP depletion induced by acute ammonia intoxication in rats is mediated by activation of the NMDA receptor and Na+, K+‐ATPase. J. Neurochem. 1994, 63, (6), 2172-2178.

    [16] Kosenko, E.; Kaminsky, M.; Kaminsky, A.; Valencia, M.; Lee, L.; Hermenegildo, C.; Felipo, V., Superoxide production and antioxidant enzymes in ammonia intoxication in rats. Free Radical Res. 1997, 27, (6), 637-644

    [17] Hurvitz, A.; Bercovier, H.; Van run, J., Effect of ammonia on the survival and the immune response of rainbow trout (Oncorhynchus mykiss, Walbaum) vaccinated against Streptococcus iniae Fish Shellfish Immunol. 1997, 7, (1), 45-53

    [18] Eddy, F., Ammonia in estuaries and effects on fish. J. Fish Biol. 2005, 67, (6), 1495-1513

    [19] Sousa, R. J.; Meade, T. L., The influence of ammonia on the oxygen delivery system of coho salmon hemoglobin. Comp. Biochem. Phys. A 1977, 58, (1), 23-28.

    [20] Ip, Y.; Chew, S.; Randall, D., Ammonia toxicity, tolerance, and excretion. Fish Physiol. 2001, 20, 109-148

    [21] Schuwerack, P.-M.; Lewis, J.; Hoole, D.; Morley, N., Ammonia-induced cellular and immunological changes in juvenile Cyprinus carpio infected with the blood fluke Sanguinicola inermis. Parasitology 2001, 122, (03), 339-345

    [22] Vogelbein, W.; Shields, J.; Haas, L.; Reece, K.; Zwerner, D., Skin ulcers in estuarine fishes: a comparative pathological evaluation of wild and laboratory-exposed fish. Environ. health Persp. 2001, 109, (Suppl 5), 687

    [23] Benli, A. . K.; Kksal, G.; ?zkul, A., Sublethal ammonia exposure of Nile tilapia (Oreochromis niloticus L.): Effects on gill, liver and kidney histology. Chemosphere 2008, 72, (9), 1355-1358

    [24] Spencer, P.; Pollock, R.; Dubé, M., Effects of un-ionized ammonia on histological, endocrine, and whole organism endpoints in slimy sculpin (Cottus cognatus). Aquat. Toxicol. 2008, 90, (4), 300-309

    [25] Miron, D. d. S.; Moraes, B.; Becker, A. G.; Crestani, M.; Spanevello, R.; Loro, V. L.; Baldisserotto, B., Ammonia and pH effects on some metabolic parameters and gill histology of silver catfish, Rhamdia quelen (Heptapteridae). Aquaculture 2008, 277, (3), 192-196

    [26] Felipo, V.; Kosenko, E.; Mi?ana, M.-D.; Marcaida, G.; Grisolia, S., Molecular mechanism of acute ammonia toxicity and of its prevention by L-carnitine. In Hepatic Encephalopathy, Hyperammonemia, and Ammonia Toxicity, Springer: 1994; pp 65-77

    [27] Randall, D.; Tsui, T., Ammonia toxicity in fish. Mar. Pollut. Bull. 2002, 45, (1), 17-23

    [13] Hegazi, M. M.; Attia, Z. I.; Ashour, O. A., Oxidative stress and antioxidant enzymes in liver and white muscle of Nile tilapia juveniles in chronic ammonia exposure. Aquat. Toxicol. 2010, 99, (2), 118-125

    [14] Yang, W.; Xiang, F.; Sun, H.; Chen, Y.; Minter, E.; Yang, Z., Changes in the selected hematological parameters and gill Na+/K+ ATPase activity of juvenile crucian carp Carassius auratus during elevated ammonia exposure and the post-exposure recovery. Biochem. Syst. Ecol. 2010, 38, (4), 557-562

    [15] Kosenko, E.; Kaminsky, Y.; Grau, E.; Mi?ana, M. D.; Marcaida, G.; Grisolía, S.; Felipo, V., Brain ATP depletion induced by acute ammonia intoxication in rats is mediated by activation of the NMDA receptor and Na+, K+‐ATPase. J. Neurochem. 1994, 63, (6), 2172-2178.

    [16] Kosenko, E.; Kaminsky, M.; Kaminsky, A.; Valencia, M.; Lee, L.; Hermenegildo, C.; Felipo, V., Superoxide production and antioxidant enzymes in ammonia intoxication in rats. Free Radical Res. 1997, 27, (6), 637-644

    [17] Hurvitz, A.; Bercovier, H.; Van run, J., Effect of ammonia on the survival and the immune response of rainbow trout (Oncorhynchus mykiss, Walbaum) vaccinated against Streptococcus iniae Fish Shellfish Immunol. 1997, 7, (1), 45-53

    [18] Eddy, F., Ammonia in estuaries and effects on fish. J. Fish Biol. 2005, 67, (6), 1495-1513

    [19] Sousa, R. J.; Meade, T. L., The influence of ammonia on the oxygen delivery system of coho salmon hemoglobin. Comp. Biochem. Phys. A 1977, 58, (1), 23-28.

    [20] Ip, Y.; Chew, S.; Randall, D., Ammonia toxicity, tolerance, and excretion. Fish Physiol. 2001, 20, 109-148

    [21] Schuwerack, P.-M.; Lewis, J.; Hoole, D.; Morley, N., Ammonia-induced cellular and immunological changes in juvenile Cyprinus carpio infected with the blood fluke Sanguinicola inermis. Parasitology 2001, 122, (03), 339-345

    [22] Vogelbein, W.; Shields, J.; Haas, L.; Reece, K.; Zwerner, D., Skin ulcers in estuarine fishes: a comparative pathological evaluation of wild and laboratory-exposed fish. Environ. health Persp. 2001, 109, (Suppl 5), 687

    [23] Benli, A. . K.; Kksal, G.; ?zkul, A., Sublethal ammonia exposure of Nile tilapia (Oreochromis niloticus L.): Effects on gill, liver and kidney histology. Chemosphere 2008, 72, (9), 1355-1358

    [24] Spencer, P.; Pollock, R.; Dubé, M., Effects of un-ionized ammonia on histological, endocrine, and whole organism endpoints in slimy sculpin (Cottus cognatus). Aquat. Toxicol. 2008, 90, (4), 300-309

    [25] Miron, D. d. S.; Moraes, B.; Becker, A. G.; Crestani, M.; Spanevello, R.; Loro, V. L.; Baldisserotto, B., Ammonia and pH effects on some metabolic parameters and gill histology of silver catfish, Rhamdia quelen (Heptapteridae). Aquaculture 2008, 277, (3), 192-196

    [26] Felipo, V.; Kosenko, E.; Mi?ana, M.-D.; Marcaida, G.; Grisolia, S., Molecular mechanism of acute ammonia toxicity and of its prevention by L-carnitine. In Hepatic Encephalopathy, Hyperammonemia, and Ammonia Toxicity, Springer: 1994; pp 65-77

    [27] Randall, D.; Tsui, T., Ammonia toxicity in fish. Mar. Pollut. Bull. 2002, 45, (1), 17-23

相关文章!
  • 浅谈财政体制改革对农业与农村

    朱钇澜【摘 ? 要】 财政体制改革对于国内经济持续稳定发展发挥着积极的作用,很大程度上推动了地方经济建设。近几年来,党中央以及财务部

  • 低盐胁迫对红鳍东方鲀幼鱼肝脏

    孙梦蕾姜志强蒋洁兰王莉苹摘 要:为探讨低盐胁迫下肝脏在红鳍东方鲀(Takifugu rubripes)机体免疫中的作用,在肝脏酶活性、组织结构和基

  • 基于高职高专院校畜牧兽医专业

    陆艳凤++孙国波++张响英++章敬旗++张海波摘要:针对高职高专院校畜牧兽医专业实用型技术人才的培养,开展在教学模式和技能培训等方面的