The Study On The Effect Of Reclaimed Water Irrigation On Urban Greenland In Tianjin

Reclaimed water includes secondary effluent and more advanced treated wastewater. The research on reclaimed water irrigation of urban greenland in Tianjin includes a series of studies.Firstly comparisons was made on reclaimed water irrigating turfgrass and tap water irrigating turfgrass. Five species including Kentucky bluegrass (Poa pratensis) ,creeping bentgrass(Agrostis stolonifera), Tall rescue (Festuca arundinacea) ,Buifalograss (Buchloe dactyloides) and Zoysia grass (Zoysia japonica) were selected for the experiment. The physiology and apparent indices were studied under different growth times. In conclusion, there is no significant differences between water resource. The water can be used on turfgrass irrigation.Secondly we analyse the guide lines of the reclaimed water and the soil where the plant growth in by experiments in Tianjin Ecomomy Development Area. The mode, degree and mechanism of the influence of the plants with the reclaimed water are being discussed. The main results is shown as follows:1 The salinity in the secondary treated wastewater supply of Tianjin Ecomomy Development Area, especially the natrium and chloride level, is exceeding high. This, in the long term, will give rise to some bad effects on the soil and plants.2 EC, SAR, Na⁺,Cl^-, SO₄^2- in soil elevated significantly with, the depth increased .That will give rise to some bad effects on the plants.3 Comparing with Tap Water irrigation, long-termed common tertiary water and secondary effluent irrigation can increase effective P, effective K and OM of soil.4 Comparing with Tap Water irrigation, plant leaf Cd, Pb, Cr content are apparently higher after 1 secondary effluent irrigation, but there is no bad effect on plant growth.5 The secondary effluent irrigation has no significant effect on plant cell cytoplasm membrane permeation , photosynthesis rate and transpiration rate.6 Due to the improver irrigation and the accumulated poisonous elements, juniper (Sabina chinensis) have shown clear signs of poison.7 As to plants, there is greater endurance in the hardwood than in the evergreen.8 The turfgrass is one of those plants suitable to reclaimed water in irrigation.