Abstract:

Based on the results of the first and second pollution survey and 78 monitoring data,using methods of questionnaire and field survey,the present situation of mulching plastic film pollution were investigated and the countermeasures were analyzed. The results indicate that the total quantity of mulching film used wes about 152 025 t and the amount of mulching film residues was about 44 574 t in 2013,and the pollution distribution had obviously regional differences( i. e.the serious pollution area lied in the central Loess Plateau,and then the eastern Loess Plateau,the Hexi Corridor,the Longnan Mountains area,the Tianshui area and the Gannan Pasturing area,respectively). The results also prove the pollution of mulching plastic film varied with crops,and the level of mulching residues in corn field was obviously higher than other crops. In addition,the results reveal that the amount of mulching residues are mainly affected by the size of residual film fragments,the mulching film thickness,the cultivated land utilization way,the distance of farmland to the village,the length of using mulch film time( e. g. the mulching fragment residues of 0- 30 cm in size are respectively 27. 62,30. 78 and 42. 26 kg·hm^-2 within 1- < 10,10- < 20 and 20- 30 years),the crops variety and the mulching film techniques.By 2013,Gansu Province has established a complete system of waste mulching film recycling,sets up 231 recycling companies and 2 130 outlets,the mulching residues recovery rate was 70. 7%. Meanwhile,some effective measures have been carried out such as increasing mulching film thickness,adjusting the planting patterns,increasing organic fertilizer application,reducing mulch film repeated use,using manual and mechanical collecting and so on,and the mulching residues and pollution have decreased greatly in recent years.

Key words: mulching plastic film, residual pollution, countermeasures, Gansu Province