[Ecological suitability assessment and optimization of urban land expansion space in Guiyang City].

Based on the case study of Guiyang City, the minimum cumulative resistance model integrating construction land source, ecological rigid constraints and ecological function type resistance factor, was built by use of cost-distance analysis of urban spatial expansion resistance value through ArcGIS 9.3 software in this paper. Then, the ecological resistance of city spatial expansion of Guiyang from 2010 was simulated dynamically and the ecological suitability classification of city spatial expansion was assessed. According to the conflict between the newly increased city construction land in 2014 and its ecological suitability, the unreasonable city land spatial allocation was discussed also. The results showed that the ecological suitability zonation and the city expansion in the study area were basically consistent during 2010-2014, but the conflict between the new city construction and its land ecological suitability was more serious. The ecological conflict area accounted for 58.2% of the new city construction sites, 35.4% of which happened in the ecological control area, 13.9% in the limited development area and 8.9% in the prohibition development area. The intensification of ecological land use conflict would impair the ecological service function and ecological safety, so this paper put forward the city spatial expansion optimal path to preserve the ecological land and improve the construction land space pattern of Guiyang City so as to ensure its ecological safety.

[Temporal and spatial characteristic of nitrogen and phosphorus output in the suburb watershed around the Baihua Lake].

Identification of the main pollutants and sources has important practical significance for the control and management of water quality in Guiyang's surrounding river areas. Based on the continuous field observation of the experiment from July, 2010 to April, 2011, this paper studies the concentration of nitrogen and phosphorus loss characteristics of Maixi river watershed, which is near to Guiyang's important water source-Baihua Lake reservoir, so as to provide a reference for Guiyang suburban small watershed source pollution control. The existence of various sources and sinks in this river basin makes great changes of nitrogen output in each sample point at different times, from upstream to downstream. Although different forms of nitrogen content and phosphorus content in water at each sampling point changes with time, it still presents a certain regularity on the whole. The total nitrogen and nitrate nitrogen in July 2010 are above normal level, and the ammonia nitrogen, nitrate nitrogen and total phosphorus are at high levels in October 2010 and December. The differences of various forms of nitrogen and phosphorus content in water at each sampling point decrease from upstream to downstream. The content of TN decreases from 3.297 mg x L(-1) to 2.793 mg x L(-1), and the content of TP decreases from 0.136 mg x L(-1) to 0.098 mg x L(-1). Contrast to the upstream, the nitrogen and phosphorus content in the downstream estuary decreases significantly. But the change is not obvious and the content of ammonia nitrogen rises slightly compared with the middle reaches. From the perspective temporal and spatial variation characteristics of nitrogen and phosphorus output in the basin, the nitrogen, especially ammonia nitrogen and nitrate, has a higher risk of getting into the Baihua Lake by river runoff. The results of the study can provide a reference for the governance of nitrogen and phosphorus loss in the watershed around the Baihua Lake.