Fig. 3. Cumulative yields of ¹⁴CO₂ from the two-dimensional microcosms after spiking with ¹⁴C-pyrene as described in Table 1. Open circles denote microcosms with Scots pine and Paxillus involutus and an implant of humus plus waste oil soil (PO/0.95); solid circles denote microcosms containing an implant of humus plus waste oil soil (O/0.95); open squares denote microcosms with Scots pine and P. involutus and an implant of humus with pyrene (PH/91.2); solid squares denote microcosms with an implant of humus with pyrene (H/91.2); open triangles denote microcosms with Scots pine and P. involutus and an implant of humus with pyrene (PH/0.07); and solid triangles denote microcosms containing an implant of humus with pyrene (H/0.07). Each line gives the ¹⁴CO₂ emitted by three parallel microcosms. The bars indicate the standard deviation.