Transport dynamics of nitrogen and phosphorus along the gradient in an integrated agri-aquaculture watershed of shallow hilly water network region

doi:10.14088/j.cnki.issn0439-8114.2025.09.012

Abstract

Abstract: Luhu Lake watershed, a representative integrated agri-aquaculture watershed within shallow hilly water network region, was selected as the research area. The concentration changes of total nitrogen (TN) and total phosphorus (TP) in the migration process of the watershed were monitored along the way through the “source-process-end” method, and the changes of pollutant transport along the way under different land use types and landscape patterns were studied. The results demonstrated significant variations in soil TN and TP contents across land use types influenced by human activities. The soil TN content ranked as livestock farms > drylands > nurseries > paddy fields > villages and towns > forests, while the soil TP content was in the order of villages > drylands > livestock farms > paddy fields > forests = nurseries. Under a single rainfall event,the concentrations of runoff pollutants in different land use types also showed differences. The average concentration of TN was in the order of farms > paddy fields > villages and towns > drylands > aquaculture ponds > nursery > forests, and the average concentration of TP was in the order of farms > villages and towns > drylands > nursery > aquaculture ponds > paddy fields > forests. The transport process of pollutants in the watershed was affected by the differences in pollutant sources, paths and occurrence forms. TN and TP showed different attenuation laws along the river. The average concentration of TN was expressed as river > lake > ditch, and the average concentration of TP was expressed as ditch > river > lake. The concentrations of TN and TP in the “end” buffer zone were significantly positively correlated with the proportion of aquaculture ponds in the buffer zone（P<0.01）, and the aquaculture ponds had a higher risk of nitrogen and phosphorus pollution to the receiving water body.

Key words: agricultural non-point source pollution, nitrogen and phosphorus loss, “source-process-end” continuum, integrated agri-aquaculture, shallow hilly water network region

CLC Number:

ZHANG Qin-jing, JIANG Tian-yu, ZHUANG Yan-hua. Transport dynamics of nitrogen and phosphorus along the gradient in an integrated agri-aquaculture watershed of shallow hilly water network region[J]. HUBEI AGRICULTURAL SCIENCES, 2025, 64(9): 73-79.

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