Nocturnal Atmospheric Oxidative Processes in the Indo-Gangetic Plain and Their Variation During the COVID-19 Lockdowns

This study investigates selected secondary atmospheric responses to the widely reported emission change attributed to COVID-19 lockdowns in the highly polluted Indo-Gangetic Plain (IGP) using ground-based measurements of trace gases and particulate matter. We used a chemical box-model to show that production of nighttime oxidant, NO₃, was affected mainly by emission decrease (average nighttime production rates 1.2, 0.8 and 1.5 ppbv hr^-1 before, during and relaxation of lockdown restrictions, respectively), while NO₃ sinks were sensitive to both emission reduction and seasonal variations. We have also shown that the maximum potential mixing ratio of nitryl chloride, a photolytic chlorine radical source which has not been previously considered in the IGP, is as high as 5.5 ppbv at this inland site, resulting from strong nitrate radical production and a potentially large particulate chloride mass. This analysis suggests that air quality measurement campaigns and modeling explicitly consider heterogeneous nitrogen oxide and halogen chemistry.

Nitrogen Source Matters: High NH4/NO3 Ratio Reduces Cannabinoids, Terpenoids, and Yield in Medical Cannabis

The N form supplied to the plant, ammonium (NH₄ ⁺) or nitrate (NO₃ ^-), is a major factor determining the impact of N nutrition on plant function and metabolic responses. We have hypothesized that the ratio of NH₄/NO₃ supplied to cannabis plants affects the physiological function and the biosynthesis of cannabinoids and terpenoids, which are major factors in the cannabis industry. To evaluate the hypothesis we examined the impact of five supply ratios of NH₄/NO₃ (0, 10, 30, 50, and 100% N-NH₄ ⁺, under a uniform level of 200 mg L^-1 N) on plant response. The plants were grown in pots, under controlled environment conditions. The results revealed high sensitivity of cannabinoid and terpenoid concentrations and plant function to NH₄/NO₃ ratio, thus supporting the hypothesis. The increase in NH₄ supply generally caused an adverse response: Secondary metabolite production, inflorescence yield, plant height, inflorescence length, transpiration and photosynthesis rates, stomatal conductance, and chlorophyll content, were highest under NO₃ nutrition when no NH₄ was supplied. Ratios of 10-30% NH₄ did not substantially impair secondary metabolism and plant function, but produced smaller inflorescences and lower inflorescence yield compared with only NO₃ nutrition. Under a level of 50% NH₄, the plants demonstrated toxicity symptoms, which appeared only at late stages of plant maturation, and 100% NH₄ induced substantial plant damage, resulting in plant death. This study demonstrates a dramatic impact of N form on cannabis plant function and production, with a 46% decrease in inflorescence yield with the increase in NH₄ supply from 0 to 50%. Yet, moderate levels of 10-30% NH₄ are suitable for medical cannabis cultivation, as they do not damage plant function and show only little adverse influence on yield and cannabinoid production. Higher NH₄/NO₃ ratios, containing above 30% NH₄, are not recommended since they increase the potential for a severe and fatal NH₄ toxicity damage.

A case of pseudohyperchloraemia caused by sodium nitrate ingestion

Emergency department presentations of sodium nitrate poisoning are increasing in frequency. Point-of-care blood gas analysis is useful for identifying methaemoglobinaemia and other abnormalities in such patients. Topically applied nitrate is known to positively interfere with chloride measurement in both point-of-care instruments and automated analysers of the clinical chemistry laboratory. In this article, the authors describe a case of pseudohyperchloraemia caused by sodium nitrate, which was consumed orally for the purpose of suicide. Consistent with the established pattern of interference, the ABL800 (Radiometer Medical, Brønshøj Copenhagen) blood gas analyser produced spuriously high chloride results, whilst the Alinity (Abbott Diagnostics, Abbot Park, Illinois) automated analyser resulted in chloride measurements comparable to those of inductively coupled mass spectrometry (ICP-MS). Both instruments, measure chloride with ion-selective electrodes (ISEs). The ABL800 (Radiometer) uses a membrane electrode, which is vulnerable to permeation by lipophilic nitrate ions, whereas the Alinity (Abbott) employs a silver chloride redox electrode system that is resistant to precipitation of silver nitrate due to its relatively high solubility. These mechanistic differences likely explain why nitrate interferes with some point-of-care devices but does not appear to affect the results of automated analysers.

Exploring atmospheric free-radical chemistry in China: the self-cleansing capacity and the formation of secondary air pollution

Since 1971, it has been known that the atmospheric free radicals play a pivotal role in maintaining the oxidizing power of the troposphere. The existence of the oxidizing power is an important feature of the troposphere to remove primary air pollutants emitted from human beings as well as those from the biosphere. Nevertheless, serious secondary air-pollution incidents can take place due to fast oxidation of the primary pollutants. Elucidating the atmospheric free-radical chemistry is a demanding task in the field of atmospheric chemistry worldwide, which includes two kinds of work: first, the setup of reliable radical detection systems; second, integrated field studies that enable closure studies on the sources and sinks of targeted radicals such as OH and NO3. In this review, we try to review the Chinese efforts to explore the atmospheric free-radical chemistry in such chemical complex environments and the possible link of this fast gas-phase oxidation with the fast formation of secondary air pollution in the city-cluster areas in China.

Biodiesel Co-Product (BCP) Decreases Soil Nitrogen (N) Losses to Groundwater

This study compares a traditional agricultural approach to minimise N pollution of groundwater (incorporation of crop residues) with applications of small amounts of biodiesel co-product (BCP) to arable soils. Loss of N from soil to the aqueous phase was shown to be greatly reduced in the laboratory, mainly by decreasing concentrations of dissolved nitrate-N. Increases in soil microbial biomass occurred within 4 days of BCP application-indicating rapid adaptation of the soil microbial community. Increases in biomass-N suggest that microbes were partly mechanistic in the immobilisation of N in soil. Straw, meadow-grass and BCP were subsequently incorporated into experimental soil mesocosms of depth equal to plough layer (23 cm), and placed in an exposed netted tunnel to simulate field conditions. Leachate was collected after rainfall between the autumn of 2009 and spring of 2010. Treatment with BCP resulted in less total-N transferred from soil to water over the entire period, with 32.1, 18.9, 13.2 and 4.2 mg N kg^-1 soil leached cumulatively from the control, grass, straw and BCP treatments, respectively. More than 99 % of nitrate leaching was prevented using BCP. Accordingly, soils provided with crop residues or BCP showed statistically significant increases in soil N and C compared to the control (no incorporation). Microbial biomass, indicated by soil ATP concentration, was also highest for soils given BCP (p < 0.05). These results indicate that field-scale incorporation of BCP may be an effective method to reduce nitrogen loss from agricultural soils, prevent nitrate pollution of groundwater and augment the soil microbial biomass.

Hil

The effects of NO₃ ^- and BAP on organogenesis in shoot primordia of Utricularia praelonga subcultured in B5 liquid medium were studied. In B5 liquid basal medium supplemented with 24.73 mM KNO₃ and 2.0 mg/l BAP the subcultured shoot primordia continuously multiplied into numerous small, globular masses, while with dilution of the KNO₃ to 3 mM organogenesis was promoted. Pulse treatment of the shoot primordia with 3 mM KNO₃ in B5 liquid medium for 72 h and then transplantation to the B5 basal liquid-medium induced meristemoids in this tissue. When the shoot primordia regenerated meristemoids, they never reverted back into the proliferation cycle. The addition of BAP in the B5 liquid medium with 3 mM KNO₃ regulated the differentiation rate of the stems and leaves in the meristemoids induced in the masses of shoot primordia. The control produced 3 parts stems to 1 part leaves; medium with 0.02 mg/l BAP regenerated approximately 2 parts stems and 1 part leaves; that of 0.20 mg/l BAP 1 part stems and 2 parts leaves; and medium with 2.00 mg/l BAP regenerated leaves only.