再来一篇悦读食物链毒素，求确认~~

zxfjacob · 发表于 2012-11-8 19:23:03

食物链毒素：

水里有种化学物质，通过食物链影响了很多生物，聚了algea的例子（高亮algea有题，问为什么举这个例子，我答案是因为algea是食物链的最低端）导致食物链高端的一些动物体内聚集了大量有毒物质。但对于mammal和bird好像并没有被有毒物质影响，貌似是因为lung的结构不同，这两者lung是转换air的，而fish靠腮，反正不一样。

【疑似原文】
hyukhee已将文章进行了翻译，同学们可以直接看文章后面的中文翻译啦~~~

Biomagnification有毒化学物质在食物链各个环节中的毒性渐进 means that the level of toxin in animals' tissues rises as one moves up the food chain. For instance, as larvae eat algae, （此处有题问algae的作用，我选的是处在食物链最低端~~不知对否~） fish eat the larvae, and bigger fish eat smaller fish, the toxin present in the algae becomes increasingly concentrated; top predators like swordfish and polar因为处在食物链顶端所以毒素最高 bears end up with the highest doses in their tissues. This can happen with stable, fat-soluble脂溶性的 chemicals that aren't easily excreted in urine or feces不容易通过尿或粪便排泄出去. Biomagnification was first studied in the late 1960s in aquatic水上的 food webs, explains Frank Gobas, professor at Simon Fraser University and leader of the study. To screen chemicals, scientists began using a property known as Kow水分配系数, which indicates how readily a chemical dissolves in water compared with fat and thus predicts how easily it will move from a fish's blood lipids into water through its gills鳃. Low-Kow, or more water soluble可溶解的, chemicals don't build up in the fish food chain and were assumed to be safe. Gobas这个人第一个发现了这种化学物质可以在水中溶解，鱼可以很容易地通过鳃来排泄。Gobas一开始认为low-Kow安全。

Environmental chemists realized, however , that this assumption might not hold in food chains involving mammals and birds because their lungs are in contact with air, not water. This means that many chemicals that are relatively soluble in water and therefore don't accumulate in fish might remain in the tissues of land animals if they aren't volatile enough to easily move from the lungs into the air (predicted by a property called Koa空气分配系数). Supporting this idea, some organic chemicals that don't biomagnify in fish appeared to be doing so in other wildlife and humans. 但是，环境学家认为这个假设不对，提出哺乳动物和鸟类可能不能排泄这种化学毒素，因为它们的肺接触空气而不是水。Koa

To explore this hypothesis, Gobas and graduate student Barry Kelly and colleagues collected plant and animal tissue samples— from lichens青苔 to beluga 白鲸whales killed in Inuit hunts—in the Arctic, where, because of weather patterns and cold temperatures, organic pollutant levels are high. They tested the samples not only for known POPs but also for several chemicals with a low Kow but high Koa, which suggested they might biomagnify in air-breathing animals. The measured levels of contaminants for various animals in aquatic and land food webs were similar to those predicted from a bioaccumulation model incorporating合并一体化 Koa and Kow, suggesting the model was correct. Chemicals with low Kow and high Koa stood out as potentially risky. 最后Gobas也说Low Kow并且high Koa的有潜在危险的，证实了Biomagnification，即毒素随着食物链的增长会沉积。

问题：（2道细节题）
1、algae的作用海藻处在食物链最低端毒素最低

附：感谢hyukhee 童鞋提供的翻译
B是指毒素通过动物组织沿着食物链移动。例如，幼虫larvae吃海藻algae，鱼吃幼虫，大鱼吃小鱼，毒素在海藻中的含量增加，顶层的如swordfish和polar bears的掠食者积累最多。这（化学物质在掠食者中积累）是稳定的，因为脂溶性的fat-soluble化学物质不容易通过尿urine或粪便feces排泄出去。第一次发现B是在1960s SFU的教授Frank Gobas研究水中食物网的时候。为了反映化学物质，科学家开始使用KOW来观察含脂肪的化学物质是如何在水中溶解的，并且可以预测这种化学物质怎么通过鱼的腮gill，从鱼的血液里流入水中。Low-Kow说明这种水溶性的化学物质不影响鱼的食物链，并且是很安全的。

但是，环境化学家发现，这个假设在mammal和bird的食物链中不成立，因为他们是靠肺lung和air接触的，不是靠水。这就意味着许多水溶性的化学物质不能够在鱼的体内积累，却能够在陆地动物的体内积累，如果他们不容易挥发的话（可以用Koa来预测）。所以，一些不在鱼中进行B的化学物质却可以在其他野生动物和人类中进行B。（就是可以在mammal和bird的食物链中转移毒素）

为了探索这个假设，Gobas和他的学生Barry Kelly还有同事们收集了植物和动物的组织样本——从青苔lichens到白鲸beluga whales——在北极，由于其气候和低温，器官内的污染物质（毒素）会积累很多。他们测试这些样本不仅仅是为了知道POPs，还为了找到一些low Kow但是high Koa的化学物质，这些化学物质意味着在air-breathing animals中有B。不同动物，水或者陆地，的食物网中污染物质含量和合并Koa and Kow预测的结果相似，说明这个模型是正确的。low Kow and high Koa的化学物质有潜在的风险。

zkybq · 发表于 2012-11-8 19:24:46

这个我考过了~

wangpengowen · 发表于 2012-11-8 19:25:38

求今天参加考试的同学来确认

ClaudiaJL · 发表于 2012-11-8 19:25:52

小J你等我Chrome安装好就可以考古啦~（○゜?゜）ノ

木寻云 · 发表于 2012-11-8 19:26:06

食物链顶层毒素
2008年4月
【1】这个食物链的最高层上容易积累某种毒素,比如POLAR BEAR, 用某种方法可以测一种叫KOW的玩意,它越高还是低忘了,毒素就越容易扩散到水里去,所以就无害了.然后说但是这方法在陆地上没用,因为鸟和捕乳动物都用肺呼吸,就算KOW低,也排不出去.最后说科学家研究了一种新的模型能测KOW和KO***玩意的混合体,成功了。
http://forum.chasedream.com/dispbbs.asp?boardID=22&ID=319210&page=1
【2】第一篇：讲一个food chain ,
第一段这个食物链的最高层上容易积累某种毒素,比如POLAR BEAR, 用某种方法可以测一种叫KOW的玩意,它越高还是低忘了,毒素就越容易扩散到水里去,所以就无害了.
第二段然后说但是这方法在陆地上没用,因为鸟和捕乳动物都用肺呼吸,就算KOW低,也排不出去. （这里有道细节题！）
http://forum.chasedream.com/dispbbs.asp?boardID=22&ID=320732&page=1
据laipiyu说是原文，大家一定重视：
Biomagnification means that the level of a toxin in animals' tissues rises as one moves up the food chain. For instance, as larvae eat algae, fish eat the larvae, and bigger fish eat smaller fish, the toxin present in the algae becomes increasingly concentrated; top predators like swordfish and polar bears end up with the highest doses in their tissues. This can happen with stable, fatsoluble chemicals that aren't easily excreted in urine or feces. Biomagnification was first studied in the late 1960s in aquatic food webs, explains Frank Gobas, professor at Simon Fraser University and leader of the study. To screen chemicals, scientists began using a property known as Kow, which indicates how readily a chemical dissolves in water compared with fat and thus predicts how easily it will move from a fish's blood lipids into water through its gills. Low-Kow, or more watersoluble, chemicals don't build up in the fish food chain and were assumed to be safe.
Environmental chemists realized, however, that this assumption might not hold in food chains involving mammals and birds because their lungs are in contact with air, not water. This means that many chemicals that are relatively soluble in water and therefore don't accumulate in fish might remain in the tissues of land animals if they aren't volatile enough to easily move from the lungs into the air (predicted by a property called Koa). Supporting this idea, some organic chemicals that don't biomagnify in fish appeared to be doing so in other wildlife and humans.

木寻云 · 发表于 2012-11-8 19:26:41

小J你等我Chrome安装好就可以考古啦~（○゜?゜）ノ

-- by 会员 ClaudiaJL (2012/11/8 19:25:52)

软软你的表情好丰富！！！

zxfjacob · 发表于 2012-11-8 19:27:31

木木，你们太速度了...我看都看不过来了...

[考古] 再来一篇悦读食物链毒素，求确认~~

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