The document discusses indicators used to measure water pollution in the Mekong Delta and Ho Chi Minh City areas. It outlines two types of indicators: biological indicators like benthic macroinvertebrates, and chemical indicators such as dissolved oxygen, nitrates, hardness, phosphates, carbon dioxide, and acidity. The presence of different classes of macroinvertebrates and levels of chemicals can provide information about the health of water bodies and potential effects on local ecosystems and human health. The document also examines common causes of water pollution like agricultural and industrial runoff and their environmental impacts.

1. Water Pollution Indicators of the Mekong Delta Grade 7 Science Saigon South International School Week Without Walls 2010

8. Class 1 Organisms are pollution sensitive. They are associated with good water quality. They do not tolerate pollution well, and large numbers are observed only when good water quality is present.

9. Class 2 Organisms somewhat pollution tolerant. They tolerate water pollution better than Class 1 organisms. We can expect to see significant numbers of these animals when the water quality ranges from good to moderate.

10. Class 3 Organisms are pollution tolerant. They are tolerant to even higher levels of pollution than are Class 2. When these animals dominate, poor water quality is generally the reason.

16. U.S. Fertilizer Loss Nitrogen runoff