城市化对甘肃省牛谷河沉积物氮磷分布的影响

Effect of Urbanization Level on the Distribution of Nitrogen and Phosphorus in Niugu River of Gansu Province

人类活动往往伴随着不同程度的水体污染物排放,对当地河流存在较大影响。为探究城市化发展差异对流经河流沉积物营养盐的分布影响,文章沿甘肃省牛谷河布设了42个断面,根据城市化程度差异划分了村落、乡镇和县城3种不同的区域,并分析了河流沉积物中营养盐含量特征及牛谷河营养盐与城市化之间的关系,结果表明:(1)牛谷河总氮总磷含量(ρTN、ρTP)在不同城市化水平区段存在显著差异,p<0.05差异系数为0.673,ρTN和ρTP皆呈村落段<县城段<乡镇段态势;(2)从离岸关系看,牛谷河沉积物中ρTN和ρTP分布呈明显的两岸低于河心的特征;(3)垂直分布角度分析发现,牛谷河沿岸城市化起步时间上表现为县城段早于村落段早于乡镇段,还表现出了城市化程度越高垂直分布离散性越大的特征;(4)Spearman相关性检验表明,在0.01水平上牛谷河沉积物ρTN和ρTP在全空间分布上呈显著相关,二者具有高度的同源性;(5)表层沉积物中ρTN和ρTP的蓄积与城市化水平相关,且同特征指标满足y(TP)=9.146×10-7x2+0.012x+722.578、y(TN)=2.434×10-9x2+4.135×10-6+0.425的关系,R2(TP)=0.787、R2(TN)=0.954。综合来看,不同城市化水平决定了河流ρTN、ρTP的分布差异,且沉积物中ρTN和ρTP的蓄积与城市化人口参数存在高度的关联性,在营养盐输入以外源为主的流域这种类似的规律可能普遍存在。

Human activities are often accompanied by different degrees of water pollutant emissions,which have a greater impact on local rivers.In order to explore the influence of urbanization development on the distribution of nutrients flowing through river sediments,42 sections were set up along Niugu River in Gansu Province.Three different areas of villages,towns and counties were divided according to the degree of urbanization,the characteristics of nutrients content in sediments and the relationship between nutrients and urbanization in Niugu River were analyzed.The results showed that there were significant differences in content of total nitrogen and total phosphorus(ρTNandρTP)in different urbanization levels of Niugu River.The difference coefficient was 0.673(p<0.05),with the trend as villages part<counties part<towns part.From the perspective of offshore relations,ρTNandρTPof river sediments in both sides was significantly lower than the river core.The analysis of vertical distribution showed that the starting time of urbanization along the River was that the country part was earlier than the village,which was also earlier than the towns part.And it also showed that the higher the degree of urbanization,the greater the dispersion of vertical distribution.Spearman correlation result showed that there was significantly correlation betweenρTNandρTPat 0.01 level in the overall spatial distribution,indicating the two had a high degree of homology.The accumulation ofρTNandρTPin surface sediments was related to the level of urbanization,and the relationship between the content ofρTNandρTPand the urbanization index were expressed as y(TP)=9.146×10-7 x2+0.012 x+722.578 and y(TN)=2.434×10-9 x2+4.135×10-6+0.425.Among them,R2(TP)=0.787,R2(TN)=0.954.On the whole,the different urbanization levels determine the distribution difference ofρTNandρTPin river,and the accumulation ofρTNandρTPwere highly correlated with urban population parameters in sediments.A similar rule may exist in the basins where the nutrient input is exogenous.