Aim

Potassium (K) is the second most abundant nutrient in plant photosynthetic tissues after nitrogen (N). Thousands of physiological and metabolic studies in recent decades have established the fundamental role of K in plant function, especially in water-use efficiency and economy, and yet macroecological studies have mostly overlooked this nutrient.



Methods

We have reviewed available studies on the content, stoichiometry and roles of K in the soil–plant system and in terrestrial ecosystems. We have also reviewed the impacts of global change drivers on K content, stoichiometry and roles.



Conclusions

The current literature indicates that K, at a global level, is as limiting as N and phosphorus (P) for plant productivity in terrestrial ecosystems. Some degree of K limitation has been seen in up to 70% of all studied terrestrial ecosystems. However, in some areas atmospheric K deposition from human activities is greater than that from natural sources. We are far from understanding the K fluxes between the atmosphere and land, and the role of anthropogenic activities in these fluxes. The increasing aridity expected in wide areas of the world makes K more critical through its role in water-use efficiency. N deposition exerts a strong impact on the ecosystem K cycle, decreasing K availability and increasing K limitation. Plant invasive success is enhanced by higher soil K availability, especially in environments without strong abiotic stresses. The impacts of other drivers of global change, such as increasing atmospheric CO2 or changes in land use, remain to be elucidated. Current models of the responses of ecosystems and carbon storage to projected global climatic and atmospheric changes are now starting to consider N and P, but they should also consider K, mostly in arid and semi-arid ecosystems.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/geb.12259

Potassium: a neglected nutrient in global change.

PM 2.5 in the Yangtze River Delta, China: Chemical compositions, seasonal variations, and regional pollution events

Levoglucosan as a tracer of biomass burning: Recent progress and perspectives

Based on a network of field stations belonging to the Chinese Academy of Sciences (CAS), the Campaign on Atmospheric Aerosol Research network of China (CARE-China) was recently established as the country’s first monitoring network for the study of the spatiotemporal distribution of aerosol physical characteristics, chemical components, and optical properties, as well as aerosol gaseous precursors. The network comprises 36 stations in total and adopts a unified approach in terms of the instrumentation, experimental standards, and data specifications. This ongoing project is intended to provide an integrated research platform to monitor online PM2.5 concentrations, nine-size aerosol concentrations and chemical component distributions, nine-size secondary organic aerosol (SOA) component distributions, gaseous precursor concentrations (including SO2, NOx, CO, O3, and VOCs), and aerosol optical properties. The data will be used to identify the sources of regional aerosols, the relative contributions fr...

The Campaign on Atmospheric Aerosol Research Network of China: CARE-China

. Biomass burning (BB) largely modifies the chemical composition of atmospheric aerosols on the globe. We collected aerosol samples (TSP) at Cape Hedo, on subtropical Okinawa Island, from October 2009 to February 2012 to study anhydrosugars as BB tracers. Levoglucosan was detected as the dominant anhydrosugar followed by its isomers, mannosan and galactosan. We found a clear seasonal trend of levoglucosan and mannosan with winter maxima and summer minima. Positive correlation was found between levoglucosan and nss-K+ (r = 0.38, p

/pdf/effect-of-biomass-burning-over-the-western-north-pacific-rim-2t7o0y8nw1.pdf

Effect of biomass burning over the western North Pacific Rim: wintertime maxima of anhydrosugars in ambient aerosols from Okinawa

Use of levoglucosan, potassium, and water-soluble organic carbon to characterize the origins of biomass-burning aerosols

Total sugars in atmospheric aerosols: An alternative tracer for biomass burning

[1] Strong diurnal cycles in ambient aerosol mass were observed in a rural region of Southeast Brazil where the trace composition of the lower troposphere is governed mainly by emissions from agro-industry. An optical particle counter was used to record size-segregated aerosol number concentrations between 13 May 2010 and 15 March 2011. The data were collected every 10 min and used to calculate aerosol mass concentrations. Aerosol samples were also collected onto filters during daytime (10:00–16:00 local time) and nighttime (20:00–06:00) periods, for subsequent analysis of soluble ions and water-soluble organic carbon. Biomass burning aerosols predominated during the dry winter, while secondary aerosols were most important in the summer rainy season. In both seasons, diurnal cycles in calculated aerosol mass concentrations were due to the uptake of water by the aerosols and, to a lesser extent, to emissions and secondary aerosol formation. In neither season could the observed mass changes be explained by changes in the depth of the boundary layer. In the summer, nighttime increases in aerosol mass ranged from 2.7-fold to 81-fold, depending on particle size, while in the winter, the range was narrower, from 2.2-fold to 9.5-fold, supporting the possibility that the presence of particles derived from biomass burning reduced the overall ability of the aerosols to absorb water.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/jgrd.50630

An analysis of diurnal cycles in the mass of ambient aerosols derived from biomass burning and agro‐industry

Using biomass (e.g. sugarcane bagasse) as biofuel in industries and distilleries is already well known and has recently been increasingly more utilized to produce heat and energy, thus emissions from burning this fuel have reached local and global populations. Biomass burning in general is the major anthropogenic source of many air pollutants. Environmental assessments must be carried out frequently and should consider not only burning fields, which are still recurrent, but also the use of bagasse as fuel, its emissions and the control in industry, taking into account air quality and harmful effects on health. In order to evaluate the atmospheric changes and the effect of the compounds emitted during biomass combustion on human health, particulate matter (PM) emission control and characterization must be carried out. Particles emitted by biomass burning have varied compositions, including organic, inorganic as well as elemental carbon. These analyses can identify different emission sources, such as fixed sources, air mass trajectories and quantification of open burning. However, ambient air quality standards should be reassessed, including the effects of ultrafine particulate matter (nanoparticles) and solutions should be sought to reduce the concentration of these materials in the atmosphere and hence improve public health.

Michele Lima-Souza

Papers

Use of levoglucosan, potassium, and water-soluble organic carbon to characterize the origins of biomass-burning aerosols

Total sugars in atmospheric aerosols: An alternative tracer for biomass burning

An analysis of diurnal cycles in the mass of ambient aerosols derived from biomass burning and agro‐industry

Nanoparticles Emitted by Biomass Burning: Characterization and Monitoring of Risks