Centennial-scale analysis of the creation and fate of reactive nitrogen in China (1910–2010)

Abstract

Human mobilization and use of reactive nitrogen (Nr) has been one of the major aspects of global change over the past century. Nowhere has that change been more dramatic than in China, where annual net Nr creation increased from 9.2 to 56 Tg from 1910 to 2010. Since 1956, anthropogenic Nr creation exceeded natural Nr creation, contributing over 80% of total Nr until 2010. There is great interest and uncertainty in the fate and effects of this Nr in China. Here, a comprehensive inventory of Nr in China shows that Nr (including recycled Nr) has continuously and increasingly accumulated on land (from 17 to 45 Tg), accompanied by increasing transfers to the atmosphere (before deposition; from 7.6 to 20 Tg), inland waters (from 2.7 to 9.6 Tg), and coastal waters (from 4.5 to 7.7 Tg) over the past 30 y. If current trends continue, Nr creation from human activities will increase to 63 Tg by 2050, raising concerns about deleterious environmental consequences for land, air, and water at regional and global scales. Tremendous amounts of Nr have accumulated in plants, soils, and waters in China over the past 30 y, but the retention capacity of the terrestrial landscape seems to be declining. There is a possibility that the negative environmental effects of excessive Nr may accelerate in coming decades, increasing the urgency to alter the trajectory of increasing Nr imbalance. Here, a conceptual framework of the relationships between human drivers and Nr cycling in China is oriented and well-targeted to Chinese abatement strategies for Nr environmental impact.

Nitrogen Loss through Anaerobic Ammonium Oxidation Coupled to Iron Reduction from Paddy Soils in a Chronosequence

“…Figure 1a and Table 2). All soil slurries were preincubated anoxically to remove indigenous O 2 and NO x − . The residual NO x − concentrations in all soil slurries after the preincubation were 0.72−1.6 mg N kg −1 .…”

An overlooked nitrogen loss linked to anaerobic ammonium oxidation in estuarine sediments in China

“…It was estimated that nearly 20% of the total nitrogen loss, mostly in the form of nitrate, was transported into estuarine and coastal ecosystems in the past three decades through riverine discharge and atmospheric deposition (Cui et al 2013), resulting in water pollution (e.g., coastal eutrophication, hypoxia, harmful algae blooms) (Deegan et al 2012). Thus, estuaries are thought to be a potential sink of nitrogen, especially nitrate, which is the substrate for many nitrogen cycling processes (e.g., denitrification and anammox).…”

Species identity of biocrust-forming lichens drives the response of soil nitrogen cycle to altered precipitation frequency and nitrogen amendment

“…Climate change models predict major changes in rainfall amounts and patterns in drylands worldwide during the second half of this century (Solomon, 2007). In parallel to climate change, environmental nitrogen (N) inputs resulting from anthropogenic activities is changing the N cycle in terrestrial ecosystems (Vitousek et al, 1997;Cui et al, 2013), affecting ecosystem processes (Phoenix et al, 2012;. Despite global change drivers are known to interact in their impacts on ecosystem services, we have limited knowledge on how the interaction between important factors such as decreasing rainfall frequency and increasing N inputs will affect ecosystem functioning in drylands (e. g. N cycle) and influence microbial communities; which carry out vital ecosystem functions (Fay et al, 2008;Delgado-Baquerizo et al, 2014).…”