生物链与毒素积累【考古待确认】

　　【原始】

　　一些毒物会随着生物链累积。越高端的检测到越多。生活在水里的动物lung可以帮忙分散一些。但当陆地动物等也参与到食物链就不一样了…考古吧…

　　【考古】

　　V1. P1先介绍了toxin可以通过食物链不断往食物链顶端累计，然后好像说了一个实验，特出一个什么结论，但是这个实验只是针对水里的动物的。P2就开始说however上面的实验没有包含陆生动物，然后分析了一通关于化学物质污染物啥的跟水生陆生动物的关系。

　　V2. 【疑似原文，待确认】

　　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。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。