A laboratory simulation test with natural water and sediments to study biod
egradability of low concentrated chemicals in surface waters was evaluated
by measuring the mineralisation and fate of 0.37 mu g kg(-1) [C-14]-4-nitro
phenol. 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 radioact
ivity between the different compartments and the physicochemical and biolog
ical state of the sediment-water systems were studied. During 35 days of in
cubation, non-reducing conditions prevailed in the test reactors and the ov
erall microbial activity did not vary substantially. The aeration method, t
he sediment and water origin and temperature significantly influenced miner
alisation, whereas illumination only slightly affected mineralisation and t
he 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. (C) 1999 Elsevier Scien
ce Ltd. All rights reserved.