环境因子对香溪河库湾淹没土壤磷释放的影响

Environmental Factors on Release of Phosphorus from Submerged Soils in Xiangxi Bay

三峡工程建成后大量的耕地良田被淹没,淹没土壤对水体环境的影响问题受到各方关注,该研究针对不同利用类型的土壤进行磷释放研究,评价淹没土壤的营养释放对三峡支流水体富营养化进程的影响。采集香溪河库湾的3种不同利用类型的土壤,通过静态淹水模拟实验,研究3种土壤的磷释放特点,结果表明:施肥次数多且土质松软的菜地土对上覆水TP含量影响最大,柑橘园土其次。菜地土的磷释放量为柑橘园土的1.7倍。林地土其自身磷含量较小,上覆水无明显影响。TP累积释放量为:不同pH下,TP累积释放量之间的大致关系为:pH=11.02时,TP累积释放量最大,为4.710 mg/kg;pH=3.98时次之,为3.645 mg/kg;pH=7.01时最小,为2.235 mg/kg。水温的升高能够有效加速受淹土壤内源磷的释放,在30℃条件下,土壤的TP最大释放量分别约为10℃,20℃时的1.7倍、4.2倍。因此冬季淹没土壤的释放对水体TP的影响较小;而夏季库区水温升高,引起淹没土壤磷的释放。

Effects of submerged soils on water environment arouse great attentions due to the impoundment of the Three Gorges, so it is important to study the rules of nutrients release such as phosphorus of submerged soils in Three Gorges Reservoir. Three types of soils were collected from Xiangxi Bay in the Reservoir area and phosphorus releasing experiments were conducted. Results showed that high fertilized vegetable soils once submerged, the phosphorus from vegetable soils is relatively at high level. Phosphorus released from woodland soils is comparatively little for low content of itself. There is definite rule for how pH and temperature works for phosphorus release. Under different pH, TP release is up to the highest as 4.710 mg/kg at pH 11.02, TP up to 3.645 mg/kg at pH 3.98 and up to the minimum 2.235 mg/kg at pH 7.01. In winter, the influence set on water by release of phosphorus is relatively little, while in summer the ascending temperatures cause TP concentration accretion.