（原创）鱼类健康（疾病） 第五讲 酸度与碱度
<div style="LINE-HEIGHT: 22px; HEIGHT: 22px;"><div style="FLOAT: left;"><img alt="发贴心情" src="http://www.hxyylt.com/skins/Default/topicface/face1.gif"/></div></div><div id="textstyle_6295" style="PADDING-RIGHT: 0px; MARGIN-TOP: 10px; FONT-SIZE: 9pt; OVERFLOW-X: hidden; WIDTH: 97%; WORD-BREAK: break-all; TEXT-INDENT: 24px; LINE-HEIGHT: normal; HEIGHT: 200px; WORD-WRAP: break-word;"><p><span>鱼类健康（疾病）</span><font face="Times New Roman"><br/> </font><span>第五讲</span><font face="Times New Roman"><br/> </font><span>酸度与碱度</span><span lang="EN-US"><font face="Times New Roman"><span> </span>Fish Health<span> </span>July 22, 2007</font></span></p><p><span>回顾前面四讲，我们谈到了</span><span lang="EN-US"><font face="Times New Roman">5</font></span><span>个能够诱发鱼类疾病的因素。归纳这</span><span lang="EN-US"><font face="Times New Roman">5</font></span><span>个因素及其安全范围如下：</span></p><p><span lang="EN-US"><font face="Times New Roman">1.<span> </span></font></span><span>浑浊度：</span><span lang="EN-US"><font face="Times New Roman"> < 5NTU</font></span><span>（</span><span lang="EN-US"><font face="Times New Roman">20mg/L</font></span><span>）可接受</span></p><p><span lang="EN-US"><font face="Times New Roman">2.<span> </span></font></span><span>温度：因种类不同而各异</span></p><p><span lang="EN-US"><font face="Times New Roman">3.<span> </span></font></span><span>氧气含量（</span><span lang="EN-US"><font face="Times New Roman">O<sub>2</sub></font></span><span>）：</span><span lang="EN-US"><font face="Times New Roman">>5mg/L</font></span><span>可接受，最好达到</span><span lang="EN-US"><font face="Times New Roman">100%</font></span><span>溶解。</span></p><p><span lang="EN-US"><font face="Times New Roman">4.<span> </span></font></span><span>氮气含量</span><font face="Times New Roman"><br/> </font><span>（</span><span lang="EN-US"><font face="Times New Roman">N<sub>2</sub></font></span><span>）：</span><span lang="EN-US"><font face="Times New Roman"><102%</font></span><span>可接受，最好</span><span lang="EN-US"><font face="Times New Roman">100%</font></span><span>溶解。</span></p><p><span lang="EN-US"><font face="Times New Roman">5.<span> </span></font></span><span>二氧化碳（</span><span lang="EN-US"><font face="Times New Roman">CO<sub>2</sub></font></span><span>）：</span><span lang="EN-US"><font face="Times New Roman"><10mg/L</font></span></p><p><span>本讲我们来看看酸度（</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>）和碱度（</span><span lang="EN-US"><font face="Times New Roman">Alkalinity</font></span><span>）对鱼类健康的影响。</span><span lang="EN-US"><font face="Times New Roman">pH = -log , </font></span><span>就是指</span><span lang="EN-US"><font face="Times New Roman"> pH</font></span><span>值等于氢离子溶度的负对数。在蒸馏水中：</span><span lang="EN-US"><font face="Times New Roman">H<sup>+<span> </span></sup></font></span><span>与</span><span lang="EN-US"><font face="Times New Roman"> OH<sup>- <span> </span></sup></font></span><span>溶度均为</span><span lang="EN-US"><font face="Times New Roman">10<sup>-7</sup><br/> </font></span><span>，因此</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>为</span><span lang="EN-US"><font face="Times New Roman">7</font></span><span>，呈中性。碱度用可滴定的碱：</span><span lang="EN-US"><font face="Times New Roman">HCO<sup>3-<span> </span></sup></font></span><span>与</span><span lang="EN-US"><font face="Times New Roman"> CO<sub>3</sub><sup>2-<span> </span></sup></font></span><span>的溶度来表示。碱度是用来测量水的缓冲能力，碱度越高，缓冲能力越强，反之亦然。</span></p><p><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>的最佳范围为</span><span lang="EN-US"><font face="Times New Roman">6-8</font></span><span>，判断</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>的适合度还得与水的</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>稳定度一起考虑。水的</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>在</span><span lang="EN-US"><font face="Times New Roman">6-8</font></span><span>，但波动很大就不好。只有</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>在</span><span lang="EN-US"><font face="Times New Roman">6-8</font></span><span>并且波动不大才好。因此适当提高水的碱度可提高水的缓冲能力，</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>就波动不大。</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>值在</span><span lang="EN-US"><font face="Times New Roman">5-10</font></span><span>之间波动只可在短时间内（小于</span><span lang="EN-US"><font face="Times New Roman">10</font></span><span>天）是可接受的。</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>值小于</span><span lang="EN-US"><font face="Times New Roman">5</font></span><span>或是大于</span><span lang="EN-US"><font face="Times New Roman">10</font></span><span>都将对鱼产生剧烈的影响。当</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>值小于</span><span lang="EN-US"><font face="Times New Roman">4</font></span><span>或是大于</span><span lang="EN-US"><font face="Times New Roman">11</font></span><span>时，鱼将死亡。</span></p><p><span>碱度的最佳范围是</span><span lang="EN-US"><font face="Times New Roman">40-400mg/L</font></span><span>，</span><span lang="EN-US"><font face="Times New Roman">20-40mg/L</font></span><span>还是可以接受的。当碱度小于</span><span lang="EN-US"><font face="Times New Roman">20mg/L</font></span><span>时，水的缓冲能力很差，</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>值将剧烈波动。值得一提的是，在淡水如海口的半咸水区域的碱度是很高的，因此</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>值就很稳定，水中生物就很纷繁多样。</span></p><p><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>值过低时，鱼鳃会受到刺激，导致鱼鳃细胞增生和肥大，使鱼的正常气体，离子交换出现问题。下图显示的是显微镜下鱼鳃增生和肥大的照片：</span></p><p><span></span> <br/><img title="dvubb" alt="图片点击可在新窗口打开查看" src="http://www.hxyylt.com/skins/default/filetype/jpg.gif" border="0"/>此主题相关图片如下：clip_image002.jpg<br/><a href="http://www.hxyylt.com/UploadFile/2007-7/200772222592247664.jpg" target="_blank"><img title="dvubb" alt="图片点击可在新窗口打开查看" src="http://www.hxyylt.com/UploadFile/2007-7/200772222592247664.jpg" border="0"/></a></p><p><span lang="EN-US"></span></p><p><span>左图中</span><span lang="EN-US"><font face="Times New Roman">MC</font></span><span>为鱼腮黏液细胞的肥大，右图中</span><span lang="EN-US"><font face="Times New Roman">H</font></span><span>为鱼腮第二结构薄片基部的细胞增生。</span></p><p><span>当出现细胞增生时，鱼鳃颜色由于血管化程度下降由红转白，并有毛绒状物质。这将诱发细菌感染。但在比较酸的水中，病菌的含量将会变少。酸水还会导致血液酸中毒，血红蛋白对氧的亲和性下降，携带氧气的能力也因此下降。过高的</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>也将导致问题，主要影响了有毒性的</span><span lang="EN-US"><font face="Times New Roman">NH<sub>4</sub><sup>+ </sup></font></span><span>的排出和在淡水中鱼鳃对钠离子与氯离子的吸收。</span></p><p><span lang="EN-US"><span><font face="Times New Roman"> </font></span></span><span>解决上述由</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>过低或过高所带来的问题的方法只有一个，就是提高碱度。提高碱度的方法在水产养殖上主要是对鱼池定期加碳酸钙（因为水体会在养殖过程中降低</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>值）。在小水体养殖中，比如家庭养殖，可以定期添加煮过的苏打水。顺带提一点，酸雨对河流产生的影响不仅是由于雨本身的酸性，还主要受到河床基质的影响。如果河床基质是花岗岩，那么</span><span lang="EN-US"><font face="Times New Roman">pH</font></span><span>值将更低，影响更大。如果是是石英，影响会小些。</span></p><p><span> 罗松</span></p><p><span> 完成于厦门</span></p></div>
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