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暂时想不起来了~~~~(>_<)~~~~ ，多亏看了你的整理，时间不够秒杀的时候好感激你的 -- by 会员 Dart1122 (2012/11/23 23:23:30) 啊，又是食物链毒素么，我发来看看 17、食物链里的毒素1. 主题思路：水里有种化学物质，通过食物链影响了很多生物，举了algea的例子，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。
2. 段落大意：P1：B是指毒素通过动物组织沿着食物链移动。这种移动在不易通过尿或者粪便排泄出去的脂溶性化学物质中是稳定的。Gobas这个人是研究B的第一人。为了反映化学物质，科学家开始使用KOW这一概念，以便观察含脂肪的化学物质是如何在水中溶解的，并且预测这种化学物质怎么通过鱼的腮，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。 P2：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，因此提出Koa的概念。 P3：最后Gobas也说Low Kow并且highKoa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。 3.题目：*Q1. algae高亮，问作用/高亮algea，问为什么举这个例子。备选答案：海藻处在食物链最低端，毒素最低选了因为algea是wellknown的处于低端食物链的东西。(本月710狗主 Q48，V38) *Q2. 如果在一个Low KOW的区域的北极熊的toxic concerntration is high,infer什么备选答案：极熊是以陆生动物为食 Q3. 哪种case符合文章第二段的情况 *Q4. 关于bear的说法正确的是? 选了其身上的毒素是从algea中积累的。 (本月710狗主 Q48，V38) 4.疑似原文：Biomagnificationmeans that the level of toxin in animals' tissues rises as one moves up thefood chain. For instance, as larvae eat algae, fish eat the larvae, and biggerfish eat smaller fish, the toxin present in the algae becomes increasinglyconcentrated; top predators like swordfish and polar bears end up with thehighest doses in their tissues. This can happen with stable, fat-solublechemicals that aren't easily excreted in urine or feces. Biomagnification wasfirst studied in the late 1960s in aquatic food webs, explains Frank Gobas,professor at Simon Fraser University and leader of the study. To screenchemicals, scientists began using a property known as Kow, which indicates howreadily a chemical dissolves in water compared with fat and thus predicts howeasily it will move from a fish's blood lipids into water through its gills.Low-Kow, or more water soluble, chemicals don't build up in the fish food chainand were assumed to be safe. Environmentalchemists realized, however, that this assumption might not hold in food chainsinvolving mammals and birds because their lungs are in contact with air, notwater. This means that many chemicals that are relatively soluble in water andtherefore don't accumulate in fish might remain in the tissues of land animalsif they aren't volatile enough to easily move from the lungs into the air(predicted by a property called Koa). Supporting this idea, some organicchemicals that don't biomagnify in fish appeared to be doing so in otherwildlife and humans. Toexplore this hypothesis, Gobas and graduate student Barry Kelly and colleaguescollected plant and animal tissue samples— from lichens to beluga whales killedin Inuit hunts—in the Arctic, where, because of weather patterns and coldtemperatures, organic pollutant levels are high. They tested the samples not onlyfor known POPs but also for several chemicals with a low Kow but high Koa,which suggested they might biomagnify in air-breathing animals. The measuredlevels of contaminants for various animals in aquatic and land food webs weresimilar to those predicted from a bioaccumulation model incorporating Koa andKow, suggesting the model was correct. Chemicals with low Kow and high Koastood out as potentially risky. 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1960sSFU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BarryKelly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 andhigh Koa的化学物质有潜在的风险。
5.备注：Kow水分配系数Koa空气分配系数 -- by 会员 zxfjacob (2012/11/23 23:24:44)
就是这篇，我翻译不好，我补充的是你发的Q2那个问题 | 
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发表于 2012-11-23 23:27:37
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