Even when human effluent covers the surface of the water in a suffocating manner, water plants rely on their vascular tissues to bring oxygen from the surface down to the roots, allowing microbes to break down pollutants and turn them into nutrients. Without consuming energy or employing chemical treatments, they return clean water to rivers and the earth.
即使人類排出的污水「窒息」了整個水面，水生植物靠著疏導組織「維管束」，還能把水域上方的氧氣帶到水下的根盤區，讓菌類藉此消化、分解污染物，變成植物生長的養分，不費絲毫能源和消毒藥劑，就把乾淨的水和空氣重新還給河川和大地。