Stoichiometric determination of nitrate fate in agricultural ecosystems during rainfall events.

Zuxin Xu,Yiyao Wang,Huaizheng Li,Yiguo Hong

doi:10.1371/journal.pone.0122484

Zuxin Xu, Yiyao Wang + Show 2 more

Open Access

https://doi.org/10.1371/journal.pone.0122484

Copy DOI

Journal: PloS one	Publication Date: Apr 7, 2015
Citations: 7	License type: CC BY 4.0

Affiliation: Tongji University

Abstract

Ecologists have found a close relationship between the concentrations of nitrate (NO3 -) and dissolved organic carbon (DOC) in ecosystems. However, it is difficult to determine the NO3 - fate exactly because of the low coefficient in the constructed relationship. In the present paper, a negative power-function equation (r 2 = 0.87) was developed by using 411 NO3 - data points and DOC:NO3 - ratios from several agricultural ecosystems during different rainfall events. Our analysis of the stoichiometric method reveals several observations. First, the NO3 - concentration demonstrated the largest changes when the DOC:NO3 - ratio increased from 1 to 10. Second, the biodegradability of DOC was an important factor in controlling the NO3 - concentration of agricultural ecosystems. Third, sediment was important not only as a denitrification site, but also as a major source of DOC for the overlying water. Fourth, a high DOC concentration was able to maintain a low NO3 - concentration in the groundwater. In conclusion, this new stoichiometric method can be used for the accurate estimation and analysis of NO3 - concentrations in ecosystems.

Highlights

Since the Industrial Revolution, the amount of reactive nitrogen (N) species in the natural environment has increased by an order of magnitude, owing to the use of artificial fertilizers and fossil fuels [1]
80% of the applied N in fertilizers may be transported by precipitation to the groundwater and surface water, with most N being in the form of nitrate (NO3-) [3,4]. These conditions increase the risk of ingesting drinking water that has been contaminated with nitrates, which can lead to methemoglobinemia (“blue baby syndrome”) [5] or stomach cancer in humans [6], NO3- poisoning in animals [7], and eutrophication of aquatic ecosystems [8]
There are many rivers that are located near farmland, and the groundwater depth is below 1 m in most areas

Summary

Introduction

Since the Industrial Revolution, the amount of reactive nitrogen (N) species in the natural environment has increased by an order of magnitude, owing to the use of artificial fertilizers and fossil fuels [1]. This environment has led to an increase in food production [2]; up to. The fate of NO3- has been a popular focus of examinations of the N cycle in the global biosphere [11,12].

Objectives

Methods

Results