Biodegradation of [14C]-4-nitrophenol in a sediment–water simulation test

A laboratory simulation test with natural water and sediments to study biodegradability of low concentrated chemicals in surface waters was evaluated by measuring the mineralisation and fate of 0.37 μg kg−1 [14C]-4-nitrophenol. The effects of the sediment type, the time of sediment collection, temperature, illumination and the method of aeration on the feasibility of the test, the mineralisation of 4-nitrophenol, the distribution of radioactivity between the different compartments and the physicochemical and biological state of the sediment–water systems were studied. During 35 days of incubation, non-reducing conditions prevailed in the test reactors and the overall microbial activity did not vary substantially. The aeration method, the sediment and water origin and temperature significantly influenced mineralisation, whereas illumination only slightly affected mineralisation and the addition of organic nutrients had almost no effect on the test systems. These results, together with those of experiments with lindane were used to propose a test guideline for standardised testing.