Ключевые слова: abstract, background, backgrounds, brown, bubble, bubbles, canal, color, concepts, damage, danger, dirt, dirty, ecology, effluent, environment, environmental, floating, flowing, foam, froth, green, industrial, lake, liquid, messy, natural, nature, pattern, polluted, pollution, pond, problems, river, scum, sewage, stagnant, standing, stream, substance, surface, swamp, texture, toxic, treatment, unhygienic, waste, water, wet,