Spatiotemporal variation of nitrate concentrations in soil and groundwater of an intensely polluted agricultural area

Abstract

Nitrate pollution in groundwater is a serious problem in many parts of the world. However, due to the diffuse and common spatially over-lapping character of potential several non-point pollution sources, it is often difficult to distinguish main nitrate sources responsible for the pollution. For this purpose, we present a novel methodology applied to groundwater for an intensely polluted area. Groundwater samples were collected monthly from April 2017 to March 2018 in Shimabara City, Nagasaki, Japan. Soil samples were collected seasonally at soil surface and 50 cm depth at 10 locations during the same period. Sequential extraction by water and extract agents was performed using calcium phosphate for anions and strontium chloride for cations. Mean nitrate concentration in groundwater close to a livestock waste disposal site (hereinafter called “LWDS”) was 14.2 mg L−1, which is exceeding Japanese drinking water standards (10 mg L−1). We used coprostanol concentration, which is a fecal pollution indicator, to identify pollution sources related to livestock waste. For this purpose, we measured coprostanol (5β) and cholestanol (5α) and then calculated the sterol ratio (5β/(5β + 5α)). The ratios for three groundwater sampling sites were 0.28, 0.26, and 0.10, respectively. The sterol ratios indicated no pollution (< 0.3). However, the detection of coprostanol originating from animal and human waste showed that groundwater was clearly affected by this pollution source. Nitrate levels in the soil were relatively high in samples collected close to the LWDS and coprostanol contents were affected by livestock waste. Soil and groundwater nitrate concentrations displayed a complex but strong relationship. Nitrate contents were shown to be transported downstream from source areas in both soil and groundwater.

The Influence of Anthropogenic Activities on the Concentration of Pesticides, Physicochemical and Microbiological Properties in the Chumbao River, Andahuaylas, Perú

“…The points sampled comply with the Peruvian standard, which establishes a maximum value of 1000 µS / cm for conductivity [11], higher in the dry season and lower in the rainy season. This is due to the discharge of wastewater into the riverbed and the dragging of particulate material; similar temporal variations were reported by other authors [5], [15].…”

“…They cause pollution through runoff, as they flow over the surface of the ground dragging and dissolving substances that have been deposited in the soil. Thus, the main runoff pollutants are fertilizers, phytosanitary products, organic matter, and other toxic substances produced by livestock and certain other industrial activities [5].…”

Contradictory Impacts of Nitrate on the Dissimilatory Arsenate-Respiring Prokaryotes-Induced Reductive Mobilization of Arsenic from Contaminated Sediments: Mechanism Insight from Metagenomic and Functional Analyses

“…Recent investigations suggest that environmental factors, such as sulfate, manganese chloride, humic acid, and phosphate, significantly affect the DARPs-mediated reductive mobilization of As in contaminated soils and sediments through interfering the bacterial activities or growth. – Additionally, nitrate stands as another commonly seen environmental contaminant. Most nitrate contaminants are derived from agricultural fertilizers, microbial degradation of plant residues and animal manure, industrial wastewater, as well as weathering and transformation of N-bearing ore minerals. , In uncultivated soils, nitrate contents vary between 5 and 10 mg/kg. In cultivated soils, elevated nitrate contents are commonly detected, ranging from 30 to more than 200 mg/kg .…”

“…Most nitrate contaminants are derived from agricultural fertilizers, microbial degradation of plant residues and animal manure, industrial wastewater, as well as weathering and transformation of N-bearing ore minerals. 34,35 In uncultivated soils, nitrate contents vary between 5 and 10 mg/kg. In cultivated soils, elevated nitrate contents are commonly detected, ranging from 30 to more than 200 mg/kg.…”

Synthesis of nitrate selective anion exchange resin and denitrification of nitrate adsorbed on the resin

“…The sources of NO 3 -N and NO 2 -N contamination in groundwater include overfertilization, animal production, domestic wastewater, etc. (Pastén-Zapata et al, 2005;Wakida and Lerner, 2005;Tomiie et al, 2009;Obeidat et al, 2013;Wijayanti et al, 2013;Bourke et al, 2019;Nakagawa et al, 2021). NO 3 -N groundwater contamination is present in the southern part of Fukuoka prefecture in Japan.…”