Societal shifts due to COVID-19 reveal large-scale complexities and feedbacks between atmospheric chemistry and climate change

The COVID-19 global pandemic and associated government lockdowns dramatically altered human activity, providing a window into how changes in individual behavior, enacted en masse, impact atmospheric composition. The resulting reductions in anthropogenic activity represent an unprecedented event that yields a glimpse into a future where emissions to the atmosphere are reduced. Furthermore, the abrupt reduction in emissions during the lockdown periods led to clearly observable changes in atmospheric composition, which provide direct insight into feedbacks between the Earth system and human activity. While air pollutants and greenhouse gases share many common anthropogenic sources, there is a sharp difference in the response of their atmospheric concentrations to COVID-19 emissions changes, due in large part to their different lifetimes. Here, we discuss several key takeaways from modeling and observational studies. First, despite dramatic declines in mobility and associated vehicular emissions, the atmospheric growth rates of greenhouse gases were not slowed, in part due to decreased ocean uptake of CO2 and a likely increase in CH4 lifetime from reduced NO x emissions. Second, the response of O3 to decreased NO x emissions showed significant spatial and temporal variability, due to differing chemical regimes around the world. Finally, the overall response of atmospheric composition to emissions changes is heavily modulated by factors including carbon-cycle feedbacks to CH4 and CO2, background pollutant levels, the timing and location of emissions changes, and climate feedbacks on air quality, such as wildfires and the ozone climate penalty.

The Ocean Carbon Response to COVID-Related Emissions Reductions

The decline in global emissions of carbon dioxide due to the COVID-19 pandemic provides a unique opportunity to investigate the sensitivity of the global carbon cycle and climate system to emissions reductions. Recent efforts to study the response to these emissions declines has not addressed their impact on the ocean, yet ocean carbon absorption is particularly susceptible to changing atmospheric carbon concentrations. Here, we use ensembles of simulations conducted with an Earth system model to explore the potential detection of COVID-related emissions reductions in the partial pressure difference in carbon dioxide between the surface ocean and overlying atmosphere (ΔpCO2), a quantity that is regularly measured. We find a unique fingerprint in global-scale ΔpCO2 that is attributable to COVID, though the fingerprint is difficult to detect in individual model realizations unless we force the model with a scenario that has four times the observed emissions reduction.

Vertical eddy iron fluxes support primary production in the open Southern Ocean

The primary productivity of the Southern Ocean ecosystem is limited by iron availability. Away from benthic and aeolian sources, iron reaches phytoplankton primarily when iron-rich subsurface waters enter the euphotic zone. Here, eddy-resolving physical/biogeochemical simulations of a seasonally-forced, open-Southern-Ocean ecosystem reveal that mesoscale and submesoscale isopycnal stirring effects a cross-mixed-layer-base transport of iron that sustains primary productivity. The eddy-driven iron supply and consequently productivity increase with model resolution. We show the eddy flux can be represented by specific well-tuned eddy parametrizations. Since eddy mixing rates are sensitive to wind forcing and large-scale hydrographic changes, these findings suggest a new mechanism for modulating the Southern Ocean biological pump on climate timescales.

The Southern Ocean is an important sink of carbon via the biological pump. Here authors run high-resolution physical/biogeochemical simulations of an open-Southern Ocean ecosystem forced with a realistic seasonal cycle and confirm that (sub)mesoscale iron transport across the mixing-layer base sustains primary productivity.

Satellite sensor requirements for monitoring essential biodiversity variables of coastal ecosystems

The biodiversity and high productivity of coastal terrestrial and aquatic habitats are the foundation for important benefits to human societies around the world. These globally distributed habitats need frequent and broad systematic assessments, but field surveys only cover a small fraction of these areas. Satellite-based sensors can repeatedly record the visible and near-infrared reflectance spectra that contain the absorption, scattering, and fluorescence signatures of functional phytoplankton groups, colored dissolved matter, and particulate matter near the surface ocean, and of biologically structured habitats (floating and emergent vegetation, benthic habitats like coral, seagrass, and algae). These measures can be incorporated into Essential Biodiversity Variables (EBVs), including the distribution, abundance, and traits of groups of species populations, and used to evaluate habitat fragmentation. However, current and planned satellites are not designed to observe the EBVs that change rapidly with extreme tides, salinity, temperatures, storms, pollution, or physical habitat destruction over scales relevant to human activity. Making these observations requires a new generation of satellite sensors able to sample with these combined characteristics: (1) spatial resolution on the order of 30 to 100-m pixels or smaller; (2) spectral resolution on the order of 5 nm in the visible and 10 nm in the short-wave infrared spectrum (or at least two or more bands at 1,030, 1,240, 1,630, 2,125, and/or 2,260 nm) for atmospheric correction and aquatic and vegetation assessments; (3) radiometric quality with signal to noise ratios (SNR) above 800 (relative to signal levels typical of the open ocean), 14-bit digitization, absolute radiometric calibration <2%, relative calibration of 0.2%, polarization sensitivity <1%, high radiometric stability and linearity, and operations designed to minimize sunglint; and (4) temporal resolution of hours to days. We refer to these combined specifications as H4 imaging. Enabling H4 imaging is vital for the conservation and management of global biodiversity and ecosystem services, including food provisioning and water security. An agile satellite in a 3-d repeat low-Earth orbit could sample 30-km swath images of several hundred coastal habitats daily. Nine H4 satellites would provide weekly coverage of global coastal zones. Such satellite constellations are now feasible and are used in various applications.

Natural Variability and Anthropogenic Trends in the Ocean Carbon Sink

Since preindustrial times, the ocean has removed from the atmosphere 41% of the carbon emitted by human industrial activities. Despite significant uncertainties, the balance of evidence indicates that the globally integrated rate of ocean carbon uptake is increasing in response to increasing atmospheric CO₂ concentrations. The El Niño-Southern Oscillation in the equatorial Pacific dominates interannual variability of the globally integrated sink. Modes of climate variability in high latitudes are correlated with variability in regional carbon sinks, but mechanistic understanding is incomplete. Regional sink variability, combined with sparse sampling, means that the growing oceanic sink cannot yet be directly detected from available surface data. Accurate and precise shipboard observations need to be continued and increasingly complemented with autonomous observations. These data, together with a variety of mechanistic and diagnostic models, are needed for better understanding, long-term monitoring, and future projections of this critical climate regulation service.

Novel application of video image processing to biochemical and antimicrobial susceptibility testing

ALADIN (Analytab Products, Plainview, N.Y.) is an automated instrument that uses video imaging (computer-assisted guided video camera) for the determination of biochemical and antimicrobial susceptibility test reactions. This collaborative investigation compared video-generated results obtained with ALADIN with visually determined findings. Both approaches were used to view identical reactions. Overall agreement for biochemical and antimicrobial susceptibility tests was greater than 95%. This study demonstrates that video imaging is an acceptable approach for determining microbial responses to biochemical and antimicrobial agents and may provide, with appropriate computer modifications, more accurate and reproducible results than are possible by visual scrutiny.

Collaborative clinical laboratory evaluation of an individual MIC strip system

Susceptibility results obtained with individualized MIC strips (MICRO-MIC) agreed with the standard microdilution broth method at a level of 96% or greater for each of the 10 antimicrobial agents tested.

Quantitative antimicrobial susceptibility test for Streptococcus pneumoniae using inoculum supplemented with whole defibrinated sheep blood

The National Committee for Clinical Laboratory Standards recommends the use of lysed horse blood-supplemented Mueller-Hinton broth for determining the quantitative antimicrobial susceptibility of Streptococcus pneumoniae. This procedure may be difficult for laboratories using previously prepared or commercial MIC systems. Therefore, a study was undertaken to determine whether previously prepared microdilution trays containing Mueller-Hinton broth without blood could be used for determining the antimicrobial susceptibility of S. pneumoniae by adding whole defibrinated sheep blood to the bacterial suspension used to inoculate the trays. The presence of alpha-hemolysis was used as an indicator of bacterial growth. One hundred isolates of S. pneumoniae selected to represent a distribution of susceptibility patterns were tested by the National Committee for Clinical Laboratory Standards method and the sheep blood-supplemented-inoculum method. Greater than 94% agreement between the two methods was achieved. The sheep-blood-supplemented-inoculum procedure was highly reproducible and easy to perform and provides an acceptable alternative for determining the MICs for S. pneumoniae for laboratories using previously prepared or commercial microdilution systems.

API ZYM and API An-Ident reactions of fastidious oral gram-negative species

API ZYM and API An-Ident enzymatic substrate tests were done on six oral species which are difficult to characterize with conventional biochemical tests. "Bacteroides forsythus, the "fusiform" Bacteroides species (A. C. R. Tanner, M. A. Listgarten, M. N. Strzempko, and J. L. Ebersole, manuscript in preparation), is difficult to cultivate in broth media, yet it gave 15 positive tests in these series. The tests were able to separate this new species from species of Capnocytophaga and Fusobacterium. "B. forsythus" reactions were similar but not identical to those of reference Bacteroides species. Positive reactions for alpha-glucosidase, beta-glucosidase, alpha-fucosidase, and alpha-glucuronidase suggest that "B. forsythus" may be saccharolytic. It was the only species tested which was trypsin positive. Wolinella species, Campylobacter concisus, B. gracilis, and Eikenella corrodens are asaccharolytic, and characterization relies heavily on sensitivities to inhibitory agents. These species reacted weakly in the API ZYM and API An-Ident enzymatic substrate tests, and the reactions were not useful for separating these species. The enzyme reactions differentiated Wolinella recta and C. concisus from Selenomonas sputigena, another oral motile but saccharolytic organism.

Collaborative evaluation of the UniScept qualitative antimicrobial susceptibility test

The UniScept system (Analytab Products, Plainview, N.Y.) is a commercially prepared microdilution antimicrobial susceptibility test for the determination of qualitative susceptibility results for gram-negative and gram-positive bacteria. The system showed excellent correlation with the reference agar diffusion approach for organisms from clinical specimens and with stock and reference cultures. Intra- and interlaboratory reproducibility was high.

Collaborative evaluation of the UniScept quantitative antimicrobial susceptibility test

UniScept (Analytab Products, Plainview, N.Y.) is a commercially prepared microdilution antimicrobial susceptibility system for the determination, in a single tray, of antimicrobial MICs for gram-negative and gram-positive bacteria and those isolated from urinary tract infections. The system showed excellent correlation with the reference microdilution approach for organisms from clinical specimens and with stock and reference cultures. Intra- and interlaboratory reproducibility was high.

Effect of bambermycins on quantity, prevalence, duration, and antimicrobial resistance of Salmonella typhimurium in experimentally infected broiler chickens

Twenty broiler chickens were fed bambermycins (Flavomycin; an antibiotic produced by Streptomyces) at the rate of 3 g/ton (US) for 63 days, and 20 control birds were fed nonmedicated feed. The birds were inoculated (dosed) on the 10th and 11th feeding day with Salmonella typhimurium. The study evaluated the effects of bambermycins on Salmonella incidence, shedding, and antimicrobial resistance. Bambermycins had no effect on body weights, duration of shedding of salmonellae, number of salmonellae shed on postdosing day 3, tissue recoverability of salmonellae, and total number of resistance patterns. Bambermycins resulted in the decrease of salmonellae to be more gradual; however, both treatments were comparable at the end of the study. The majority of S typhimurium from bambermycins-treated birds maintained the original antibiogram of streptomycin, sulfadiazine, and nalidixic acid. The salmonellae isolated from the control birds were more resistant to 2 drugs (varying antibiograms). Bambermycins as a feed additive in broiler diets given at the dose level of 3 g/ton had no detrimental effects based on salmonellae shedding and antimicrobial resistance.

Laboratory evaluation of the Anderson Technical semiautomated susceptibility testing system

Anderson Technical, Inc. has developed rapid, semiautomated equipment for antimicrobial susceptibility testing. A total of 310 fresh clinical bacterial isolates (226 gram-negative and 75 gram-positive) were tested with the Anderson Technical system and compared with those of Micro-Media Systems, Inc. For the gram-positive organisms, 74.3% of the test pairs had identical minimum inhibitory concentration values, whereas 99.1 and 0.9% of the test pairs had minimal inhibitory concentration values differing by less than or equal to 1 and greater than 1 dilution level, respectively. Identical minimum inhibitory concentration values were obtained for 67.2% of the gram-negative test pairs, whereas 97.6 and 2.4% differed by less than or equal to 1 and greater than 1 dilution level, respectively. For all organisms tested, 98.0% differed by less than or equal to 1 dilution level. The Anderson Technical equipment proved to be a rapid and flexible system for microdilution testing.

Influence of salinomycin on incidence, shedding, and antimicrobial resistance of Salmonella typhimurium in experimentally infected broiler chicks

Twenty broiler chickens were fed 80 g/T salinomycin, an antibiotic produced by Streptomyces albus, and 20 birds were fed a control, unmedicated feed. The birds were experimentally infected with Salmonella typhimurium. The study evaluated the effects of salinomycin on Salmonella incidence, shedding, and antimicrobial resistance. Salinomycin had no effect on body weights, length of time salmonellae were shed, number of salmonellae shed on postdosing day 3, salmonellae tissue recoverability, or on the total number of resistance patterns. Salinomycin caused the decline of salmonellae to be more gradual; however, both treatments were comparable at the end of the study. The majority of isolated from birds receiving salinomycin maintained the original S. typhimurium antibiogram of streptomycin, sulfadiazine, and nalidixic acid. The salinomycin salmonellae were more susceptible to tetracycline, amikacin, carbenicillin, gentamicin, and cephalothin. The multiple resistance patterns of eight and nine drugs tended to be more prevalent among salmonellae from control birds than salinomycin treated birds. The antibiotic salinomycin appears to be an acceptable feed additive in broilers at the level of 80 g/T based on these results of its effects on salmonellae shedding and antimicrobial resistance.

Microbial Quality of Ground and Comminuted, Raw and Cooked Turkey Meat 1

The microbial quality of ground and comminuted turkey meat was examined using raw meat and meat after two cooking times. Eight triplicate samples were obtained from a commercial processing plant over an 8-month period and analyzed for aerobic plate count (APC), coliforms, Escherichia coli , Staphylococcus aureus , Clostridium perfringens and Salmonella . The APC for 29%of the raw ground and 0% of the raw comminuted turkey meat samples was greater than 5.0 × 10⁶/g. Raw ground and comminuted meat yielded a mean coliform most probable number (MPN) of 2.2 × 10² and 6.2 × 10²/g respectively. Mean E. coli MPNs per gram were 12 for raw ground and 49 for raw comminuted meat. Twenty-five percent of the 24 raw ground samples, and 46% of the comminuted samples exceeded 50 E. coli MPN/g. S aureus was isolated from 25% of the raw ground and 54% of raw comminuted samples. Salmonellae were isolated from 8% of the raw ground samples and 12% of raw comminuted samples. C. perfringens was isolated from 50 and 55% of 40 ground and 40 comminuted meat samples, respectively. Cooking reduced the microbial numbers and isolation frequency from all samples.

Incidence of salmonellae in fecal samples of production swine and swine at slaughter plants in the United States in 1978

Nine swine slaughter plants and 19 swine production units were randomly selected for sampling from the six highest swine-producing states representing a total of 64% of the United States swine production. Three composites of 10 fresh swine fecal samples were obtained from each slaughter plant, representing three different farm sources of swine. Two composite fecal samples were collected from two different production pens from each production unit. Samples were analyzed for salmonellae. Isolated salmonellae were biochemically and serologically identified and tested for antibiotic susceptibility and resistance transfer ability. Salmonellae were recovered from swine at seven of the nine slaughter plants and 16 of the 27 composites of slaughter swine. Of the 19 production units, 3 had swine shedding salmonellae. Resistances found included streptomycin, tetracycline, and sulfadiazine. Of the 52 total isolates tested, 71% had some level of antibiotic resistance. Only 3 of 37 resistant isolated could transfer resistance under the conditions used.