# Risk assessment and spatial-temporal distribution characteristics of nitrogen and phosphorus emissions from agricultural sources in the Yangtze River Economic Belt

## TL;DR

This study examines the decline in nitrogen and phosphorus pollution from agriculture in the Yangtze River Economic Belt from 2005 to 2020 and suggests ways to further reduce it.

## Contribution

An improved output coefficient model was used to analyze spatiotemporal trends in agricultural pollution in the Yangtze River Economic Belt.

## Key findings

- Total nitrogen and phosphorus pollution loads from agriculture decreased significantly from 2005 to 2020.
- Spatial analysis confirmed a widespread reduction in pollution across the Yangtze River Economic Belt.
- The average TN-to-TP pollution load ratio remained around 19.40 during the study period.

## Abstract

Rapid socioeconomic development has intensified nitrogen and phosphorus pollution in the Yangtze River Economic Belt (YREB), posing severe threats to the water environment. Notably, agricultural sources have surpassed industrial sources to become the primary contributor to this pollution. To explore the spatiotemporal characteristics and impacts of agricultural nitrogen and phosphorus pollution in this region, this study constructed an improved output coefficient model. Using panel data from 11 provinces and municipalities in the YREB spanning 2005–2020, combined with Geographic Information System (GIS) spatial analysis tools, we calculated the pollution loads of agricultural nitrogen and phosphorus from three key sources: land use, rural domestic activities, and livestock and poultry breeding (LPB). The results show a consistent downward trend in total nitrogen (TN) and total phosphorus (TP) pollution loads from the three sources. Specifically, TN load decreased from 2,686.68 × 103 tons/yr in 2005 to 2,035.67 × 103 tons/yr in 2020, while TP load declined from 139.42 × 103 tons/yr to 102.52 × 103 tons/yr, with an average TN-to-TP pollution load ratio of approximately 19.40. GIS-generated spatial distribution maps confirm a widespread reduction in agricultural TN and TP pollution across the region. To effectively mitigate agricultural nitrogen and phosphorus pollution risks, we recommend strengthening research on fertilization techniques for major crops and exploring the establishment of centralized treatment stations for agricultural solid waste in regions within the YREB.