1)pollution,n.污染2)NO-3-N contamination,NO3-N污染3)nitrogen pollution load,N污染负荷4)contamination,n.污染，沾染物5)N and P pollution loading,N、P污染负荷6)stain,n.污点,瑕疵 v.沾污;染色
用法和例句
Based on the livestock statistical data of 31 provinces of 1997～2004,this paper analyzed the structure of livestock and the variation of fecal nitrogen pollution load in China.