Influence of land use and landscape pattern on legacy nitrogen pollution in a typical watershed in eastern China

IF 5.4 1区农林科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Catena Pub Date : 2025-05-08 DOI:10.1016/j.catena.2025.109129

Yucang Wang , Hao Wu , Zheqi Pan , Longdan Ma , Yu Zhang , Jia Zhou , Minpeng Hu , Zhihan Cheng , Xin Zheng , Dingjiang Chen

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引用次数: 0

Abstract

Legacy effects from nonpoint source nutrient pollution reduce the effectiveness of nitrogen remediation strategies in watersheds, yet spatial landscape variations and their influence on the legacy effects remain unclear. This study addressed spatial differences in legacy nitrogen pollution within the Yongan watershed in eastern China using detrended fluctuation analysis (where H > 0.5 indicates a legacy effect). Results revealed strong legacy effects for total nitrogen (TN) and nitrate nitrogen (NO₃^–-N) at the watershed outlet, with H values of 0.70 and 0.87, respectively, primarily influenced by soil nitrogen contributions (40 ± 8 %), as revealed by isotopic source apportionment. Significant spatial variation in the legacy effect was observed across different catchments, with H-index ranging from 0.42 to 0.85 for TN and from 0.58 to 0.91 for NO₃^–-N. Land use explained 90 % of this variation, predominantly driven by grasslands (48 %), impervious surfaces (16 %), and orchards (14 %). Grasslands were found to reduce legacy effects by reducing nitrogen inputs from soil and groundwater, whereas impervious surfaces reduced the legacy effect by increasing domestic wastewater contributions. Conversely, agricultural lands (orchards, paddy fields and drylands) exacerbated the legacy effect through elevated soil nitrogen contributions. Threshold values for key landscape metrics were identified that effectively mitigated the legacy effect: increasing grassland edge density (ED) to 0.16 km/km², orchard connectivity (CONNECT) to 32 %, and impervious surface aggregation (AI) to 91 %. The integration of stable isotopes and landscape data provides a robust framework for identifying dominant nitrogen sources and uncovering the spatial mechanisms underlying legacy pollution. These findings can guide landscape management strategies and support targeted interventions for nonpoint source nitrogen control at the watershed scale.

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中国东部典型流域土地利用与景观格局对遗留氮污染的影响

非点源营养物污染的遗留效应降低了流域氮素修复策略的有效性，但空间景观变化及其对遗留效应的影响尚不清楚。本研究利用非趋势波动分析分析了中国东部永安流域遗留氮污染的空间差异(其中H >；0.5表示遗留效应)。结果表明，流域出口总氮（TN）和硝态氮（NO3—N）的H值分别为0.70和0.87，主要受土壤氮贡献（40±8%）的影响。不同流域的遗留效应空间差异显著，TN的h指数在0.42 ~ 0.85之间，NO3—N的h指数在0.58 ~ 0.91之间。土地利用解释了90%的变化，主要由草地（48%）、不透水表面（16%）和果园（14%）驱动。研究发现，草地通过减少土壤和地下水的氮输入来减少遗产效应，而不透水地表通过增加生活污水的贡献来减少遗产效应。相反，农业用地（果园、水田和旱地）通过提高土壤氮贡献而加剧了遗产效应。确定了有效缓解遗留效应的关键景观指标阈值：草地边缘密度（ED）增加到0.16 km/km2，果园连通性（CONNECT）增加到32%，不透水面聚集（AI）增加到91%。稳定同位素和景观数据的整合为确定主要氮源和揭示遗留污染的空间机制提供了一个强大的框架。这些发现可以指导景观管理策略，并支持有针对性的流域非点源氮控制干预措施。

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来源期刊

Catena 环境科学-地球科学综合

CiteScore

10.50

自引率

9.70%

发文量

816

审稿时长

54 days

期刊介绍： Catena publishes papers describing original field and laboratory investigations and reviews on geoecology and landscape evolution with emphasis on interdisciplinary aspects of soil science, hydrology and geomorphology. It aims to disseminate new knowledge and foster better understanding of the physical environment, of evolutionary sequences that have resulted in past and current landscapes, and of the natural processes that are likely to determine the fate of our terrestrial environment. Papers within any one of the above topics are welcome provided they are of sufficiently wide interest and relevance.