Помогите составить 7 предложений на тему "состояние рек и озер".

Recently be a strong anthropogenic impact on surface water bodies. This and various discharges of industrial and domestic water, and noise pollution, and disturbance of the ponds by mechanical mixing of layers of water, as well as a violation of the thermal regime. All these factors lead to various changes in aquatic ecosystems, which affects the General state of nature and on human society.
There are many chemical and physical methods for the determination of water quality, using special devices. The method of determining the purity of water by dwelling therein in the aquatic fairly affordable.