攒rp系列之三,本月阅读海藻原文(补充了最后一段)

ohohh

花了近一个小时把自然杂志的这篇文章最后一段给挖出来了,可能还缺最后一句话,但我仔细对了机经,这原文应该没有问题的,

希望对大家能有帮助,再次感谢XYXB,我觉得大家考好了都应该请她吃饭的说.

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.

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, 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 bioaccu- mulation model incorporating Koa and Kow, suggesting the model was correct. Chemicals with low Kow and high Koa stood out as potentially risky.

leeyuan1

系统提示：
RP槽已满，楼主请肆意使用～
谢谢分享！！

jiayini85

太牛了 谢谢
我想问一下考过的同学, 这篇文章机器上显示的是几行?
一般考试中,阅读是30-45行的比重多呢?还是45-60行的比重文章多呢?
进入700+以上的同学遇到的阅读有多少篇幅呢?
望考过的同学给点经验之谈 谢谢啦

lcommus

太感谢了

xz328

谢谢！

loveyj613

很好很强大！！！

XYXB

你太强啦

ext3

哥们你这RP 要爆发啦，估计800