advice alert appropriate behavior appropriate behaviour avoid black care concern danger dangerous denied directions not allowed not permitted permission denied polluted pollution prohibited prohibition protect protection red rules safety sign signs toxic toxicity warning warning sign water pollution water toxicity weathered white worn announcement appropriate-behavior appropriate-behaviour be-careful beware caution communicating communication deep health information informing not-allowed not-permitted permission-denied risk risks risky unhealthy warning-sign water water-pollution water-toxicity contaminated contamination abstract agitated agitation bubbles bubbling edge edges edging flow flowing foam foaming froth frothing frothy inlet light mixed mixing pattern patterning patterns soft stirred stirring stream surface surfaced surfaces swirling swirls texture textured textures variation varieties variety