土地利用变化下沿海地区吸附态磷负荷动态变化研究

吸附态磷是主要的面源污染物之一,它会导致水域环境质量恶化,是水体富营养化的重要污染源。科学估算吸附态磷污染负荷能够为治理沿海地区非点源污染,保护海洋生态安全提供理论依据。以遥感影像、降雨监测资料等多源数据为基础,综合考虑土壤侵蚀、泥沙输移率、磷富集系数等影响因子,构建吸附态磷负荷估算模型,估算了江苏沿海地区2000~2010年吸附态磷负荷量,分析了不同土地利用背景下吸附态磷负荷的动态变化特征,结果显示:(1)2000~2010年,江苏沿海地区吸附态磷负荷明显增加,平均吸附态磷负荷模数由105.89 kg/km2·a增长至201.67 kg/km2·a,吸附态磷负荷总量由3 284t增长至6 255t。(2)10 a间,研究区的吸附态磷负荷热点面积减小,呈现出收敛聚集的态势,但热点区的吸附态磷负荷总量却明显增加,说明研究区内吸附态磷负荷的空间极化现象更为显著。(3)10 a间,各土地利用类型的平均吸附态磷负荷模数都显著增长,不同土地利用背景下吸附态磷负荷总量排序为水田旱地林地草地未利用地园地。研究结果表明,不同土地利用背景下吸附态磷负荷存在显著差异,且不同土地利用类型相互转化时,吸附态磷负荷也随之发生变化,可通过调整土地利用结构,优化景观格局,减少和控制磷污染的发生。

RESEARCH ON THE DYNAMIC CHANGE OF ABSORBED PHOSPHORUS LOAD UNDER LAND USE CHANGE BACKGROUND IN THE COASTAL AREA S

The absorbed phosphorus is one of the major surface contaminants, which not only leads to aquatic environment degradation, but also plays a critical role in water eutrophication. In order to provide theoretical information for agricultural non-point source pollution (ANPS) management and marine ecological safety, the major purpose of this research is to assess the absorbed phosphorus loads under ANPS in the coastal areas. An estimation model of adsorbed phosphorus load was constructed by integrated soil erosion factor, sediment delivery factor and phosphorus enrichment factor together. The model was used to assess the load capacity of adsorbed phosphorus from 2000 to 2010 in the coastal areas of Jiangsu Province using GIS. Finally, the dynamic change features of absorbed phosphorus loads under different land uses were analyzed. The results showed:(1) Absorbed phosphorus load in the coastal areas of Jiangsu province increased significantly from 2000 to 2010, the average phosphorus load modulus increased from 105.89 kg/km²·a to 201.67 kg/km²·a, while the total volume of absorbed phosphorus load increased from 3284 t to 6255 t. (2) During the ten years, the hot areas of absorbed phosphorus load in the research region have narrowed, presenting a state of convergence, while the total amount of absorbed phosphorus load in the hot areas increased significantly, which indicated that the spatial polarization of phosphorus load in the research area was more obvious. (3) Within the ten years, there was a significant growth of the average phosphorus load modulus under different land use backgrounds. According to the total volume of phosphorus load in the same year, different land use types in coastal areas of Jiangsu Province ranked in the following order:paddy field > dry land > forest land > grass land > unutilized land > garden plot. The research results indicated that there was significant difference in the phosphorus load among different land use backgrounds. Therefore, the reasonable land use structure adjustment and landscape pattern optimization is beneficial to preventing and controlling phosphorus pollution.