tailieunhanh - Coastal Pollution: Effects on Living Resources and Humans - Chapter 5

Tảo nở hoa của tảo độc tính và là hiện tượng tự nhiên. Tại sao, sau đó, CHÚNG nên có một vị trí chi phối trong một cuốn sách liên quan với ô nhiễm bờ biển? Hai lý do tốt là: (1) tăng độ lân của nitơ và trong vùng nước ven biển / cửa sông - Cơ sở dân số bùng nổ cho sự phát triển của tảo phù du - đã-được thể hiện trong trường hợp nhiều nguồn gốc của con người để trở thành, và giao thông vận tải (2) của con người loài tảo độc hại. | 5 Harmful Algal Blooms in Coastal Waters INTRODUCTION ALGAL BLOOMS AND ALGAL TOXICITY Algal blooms and algal toxicity are natural phenomena. Why then should they have a dominant position in a book concerned with coastal pollution Two good reasons are 1 augmentation of levels of nitrogen and phosphorous in coastal estuarine waters the basis for explosive population growth of planktonic algae has been shown in many instances to be of human origin and 2 human transport of toxic algal species to new habitats with ships ballast water and by other commercial practices has been demonstrated and is undoubtedly of common occurrence. The frequency of occurrence areal extent and intensity of algal blooms seems to be increasing on a global scale a trend that would be expected as a consequence of human contributions of nutrient chemicals to coastal estuarine waters and of human participation in disseminating alien species. Additionally the list of types of algal toxins is gradually expanding as is the geographic extent of reported toxic events and knowledge about the nature of the toxins produced. Population explosions of planktonic unicellular algae so-called algal blooms or red tides even though many of them are not red have been observed for centuries and have in some instances caused shellfish in areas such as Puget Sound and northern New England to become temporarily toxic to humans. Paralytic shellfish poisoning PSP is the best-known consequence of eating toxic bivalve molluscs although several other types of poisoning have been described and new ones are being identified. Not all blooms are toxic but many that are not may still be harmful in a variety of ways for example by reducing light penetration by reducing dissolved oxygen levels by forming mucilaginous aggregates or by interfering with respiration of fish. The overall perception is that many if not most algal blooms can be harmful but not all harmful blooms are toxic. To make some sense of this we can create some