明天考试了……有个阅读寂静里面的问题，大谢啊！

hdyxxnn

就是第五篇这个食物链的这个，看底下那个英文原文，我觉得第一段意思是人以为鱼类是通过食物链传到毒素的，但实际不是，因为毒素可以被水溶解，所以毒素通过鱼鳃就溶解了，第一段最后一句提出来，那是不是陆地动物也是这样呢？他们可不是在水里呼吸
结果第二段就来说陆地动物的实验，他们有koa什么的，我理解就是陆地动物和鱼不一样，陆地动物没有水的稀释，所以毒素会传到，对不对？特别是我用颜色标出来的那个画怎么感觉和我理解的不一样呢？

拜托牛牛们解答一下吧~

5食物链

V1by lorein

说一些动物体内有toxin 所以这些动物所处的食物链上的动物体内也因此有toxin~然后举了个例子~举了一条食物链（此处有题问aglea的作用，我选的是处在食物链最低端~~不知对否~）再后来反驳了这个理论~貌似说处在食物链底层的那些鱼呀虾呀啥啥的和处在上层的熊呀啥啥的不一样~~就是toxin不能整个传导~好像是底层的毒传不到上层去~~x熊啥的中毒不是因为底层食物链~~只和上层吃得食物有关~~

V2by clergy1989

阅读有篇食物链的，后面一段貌似是有区分了land动物和bird这些事不一样的，因为考得都是细节题，连文章都没怎么看。。。那个algea（不知道怎么拼，大概就长成这个样子），考了两道的说，一道和之前的狗狗是一样的。。。


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 predatorslike 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 bloodlipids into water through its gills. Low-Kow, or more watersoluble, chemicalsdon't build up in the fish food chain and were assumed to be safe.
Environmental chemists realized, however, that this assumption might not holdin food chains involving mammals and birds because their lungs are in contact with air, not water. This means that many chemicals that are relatively solublein 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.
To explore this hypothesis, Gobas and graduate student Barry Kelly and colleagues collected plant and animal tissue samples— from lichens to beluga whales killed in Inuit hunts—in the Arctic,where,
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 bioaccu- mulation model incorporating Koa and Kow, suggesting the model was correct.Chemicals with low Kow and high Koa stood out as potentially risky.

chihhsin7337

我考到這篇  是最後一篇  所以沒甚細看
印象中你有疑問這個點 沒考到

文章一模一樣 看熟了!

但有一是主旨題

hdyxxnn

啊？原文啊……那主旨是研究这个毒素放大理论在鱼类和陆地类动物中？还是提出一个旧理论然后反驳它？

kathy1989717

顶上去！