The abundance, diversity and composition of bacterial communities in water wells with high nitrate and ammonium concentrations were evaluated. The main purpose of this study was to identify the impact of rural residents’ activities on groundwater microbial communities. A total of 26 wells accessing shallow aquifers in sub-catchments of Linshu Basin, China, were collected for water chemistry and microbial community structure using environmental DNA techniques. The sub-catchment showed evidence of groundwater contamination with nitrates and ammonium concentrations often well above background, with nitrate concentrations up to 3458 mg/L and ammonium concentration up to 7.4 mg/L, the nitrate isotopic (δ15N-NO3− and δ18O-NO3−) fingerprinting suggests manure and sewage were the major sources of nitrate in groundwater. The changes in microbial diversity in response to rural residents’ activities were characterized by comparing the microbial community structures in groundwater from various wells, grouped based on different nitrate and ammonium concentrations. Specifically, comparisons were made between wells with higher nitrate concentrations (above 20 mg/L) and higher ammonium concentrations (above 0.5 mg/L) versus those with lower nitrate concentrations (below 20 mg/L) and lower ammonium concentrations (below 0.5 mg/L) using the high throughput 16 S rDNA gene sequencing. Results show that higher nitrate concentrations (> 20 mg/L) significantly altered the diversity (ACE and Chao-1 indices, p < 0.05) but not the richness of wells’ microbial communities (p > 0.05), the bacterial community structures at the phylum and class level were similar. RDA results showed that the nitrate concentrations exerted no influence on groundwater’s microbial communities(p > 0.05), while the nitrogen concentrations showed obvious influence on groundwater’s microbial communities(p < 0.05). This study elucidates the multifaceted impacts of rural residents’ activities on groundwater quality, demonstrating through comprehensive hydrochemical and isotopic analyses that agricultural practices (including intensive fertilizer application and unlined manure storage), livestock operations (particularly swine and poultry waste lagoons), and inadequate domestic wastewater systems collectively contribute to groundwater contamination, with stable isotopic signatures (δ15N-NO3: +10‰ to + 20‰) providing definitive evidence that manure and sewage constitute the predominant nitrogen source, accounting for 58% of the total contamination load.

The impact of typical rural resident’s activities on groundwater microbial communities in Linshu Basin, Shandong Province, P.R. China

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2026年4月9日

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Zuobing Liang,
Wen Liu,
Zaizhi Yang,
Zuoshun Liang

摘要

The abundance, diversity and composition of bacterial communities in water wells with high nitrate and ammonium concentrations were evaluated. The main purpose of this study was to identify the impact of rural residents’ activities on groundwater microbial communities. A total of 26 wells accessing shallow aquifers in sub-catchments of Linshu Basin, China, were collected for water chemistry and microbial community structure using environmental DNA techniques. The sub-catchment showed evidence of groundwater contamination with nitrates and ammonium concentrations often well above background, with nitrate concentrations up to 3458 mg/L and ammonium concentration up to 7.4 mg/L, the nitrate isotopic (δ¹⁵N-NO₃⁻ and δ¹⁸O-NO₃⁻) fingerprinting suggests manure and sewage were the major sources of nitrate in groundwater. The changes in microbial diversity in response to rural residents’ activities were characterized by comparing the microbial community structures in groundwater from various wells, grouped based on different nitrate and ammonium concentrations. Specifically, comparisons were made between wells with higher nitrate concentrations (above 20 mg/L) and higher ammonium concentrations (above 0.5 mg/L) versus those with lower nitrate concentrations (below 20 mg/L) and lower ammonium concentrations (below 0.5 mg/L) using the high throughput 16 S rDNA gene sequencing. Results show that higher nitrate concentrations (> 20 mg/L) significantly altered the diversity (ACE and Chao-1 indices, p < 0.05) but not the richness of wells’ microbial communities (p > 0.05), the bacterial community structures at the phylum and class level were similar. RDA results showed that the nitrate concentrations exerted no influence on groundwater’s microbial communities(p > 0.05), while the nitrogen concentrations showed obvious influence on groundwater’s microbial communities(p < 0.05). This study elucidates the multifaceted impacts of rural residents’ activities on groundwater quality, demonstrating through comprehensive hydrochemical and isotopic analyses that agricultural practices (including intensive fertilizer application and unlined manure storage), livestock operations (particularly swine and poultry waste lagoons), and inadequate domestic wastewater systems collectively contribute to groundwater contamination, with stable isotopic signatures (δ¹⁵N-NO₃: +10‰ to + 20‰) providing definitive evidence that manure and sewage constitute the predominant nitrogen source, accounting for 58% of the total contamination load.