Với mong muốn giúp các bạn đạt kết quả cao trong kì thi, đã sưu tầm và chọn lọc gửi đến các bạn IELTS Academic Reading Sample 172. Mời các bạn cùng tham khảo! | You should spend about 20 minutes on Questions 15 27 which are based on Reading Passage 172 on the following pages. Contaminating the Arctic Our perception of the Arctic region is that its distance from industrial centers keeps it pristine and clear from the impact of pollution. However through a process known as transboundary pollution the Arctic is the recipient of contaminants whose sources are thousands of miles away. Large quantities of pollutants pour into our atmosphere as well as our lakes rivers and oceans on a daily basis. In the last 20 years scientists have detected an increasing variety of toxic contaminants in the North including pesticides from agriculture chemicals and heavy metals from industry and even radioactive fall-out from Chernobyl. These are substances that have invaded ecosystems virtually worldwide but they are especially worrisome in the Arctic. Originally Arctic contamination was largely blamed on chemical leaks and these leaks were thought to be small and localized. The consensus now is that pollutants from around the world are being carried north by rivers ocean currents and atmospheric circulation. Due to extreme conditions in the Arctic including reduced sunlight extensive ice cover and cold temperatures contaminants break down much more slowly than in warmer climates. Contaminants can also become highly concentrated due to their significantly lengthened life span in the Arctic. Problems of spring run-off into coastal waters during the growth period of marine life are of critical concern. Spring algae blooms easily absorbing the concentrated contaminants released by spring melting. These algae are in turn eaten by zooplankton and a wide variety of marine life. The accumulation of these contaminants increases with each step of the food chain or web and can potentially affect northerners who eat marine mammals near the top of the food chain. Pollutants respect no borders transboundary pollution is the movement of contaminants across
