Can We Detect Urban‐Scale CO2 Emission Changes Within Medium‐Sized Cities?

The COVID‐19 pandemic resulted in a widespread lockdown during the spring of 2020. Measurements collected on a light rail system in the Salt Lake Valley (SLV), combined with observations from the Utah Urban Carbon Dioxide Network observed a notable decrease in urban CO2 concentrations during the spring of 2020 relative to previous years. These decreases coincided with a ∼30% reduction in average traffic volume. CO2 measurements across the SLV were used within a Bayesian inverse model to spatially allocate anthropogenic emission reductions for the first COVID‐19 lockdown. The inverse model was first used to constrain anthropogenic emissions for the previous year (2019) to provide the best possible estimate of emissions for 2020, before accounting for emission reductions observed during the COVID‐19 lockdown. The posterior emissions for 2019 were then used as the prior emission estimate for the 2020 COVID‐19 lockdown analysis. Results from the inverse analysis suggest that the SLV observed a 20% decrease in afternoon CO2 emissions from March to April 2020 (−90.5 tC hr−1). The largest reductions in CO2 emissions were centered over the northern part of the valley (downtown Salt Lake City), near major roadways, and potentially at industrial point sources. These results demonstrate that CO2 monitoring networks can track reductions in CO2 emissions even in medium‐sized cities like Salt Lake City.Alternate :Plain Language SummaryHigh‐density measurements of CO2 were combined with a statistical model to estimate emission reductions across Salt Lake City during the COVID‐19 lockdown. Reduced traffic throughout the COVID‐19 lockdown was likely the primary driver behind lower CO2 emissions in Salt Lake City. There was also evidence that industrial‐based emission sources may of had an observable decrease in CO2 emissions during the lockdown. Finally, this analysis suggests that high‐density CO2 monitoring networks could be used to track progress toward decarbonization in the future.

Trophic state assessment of optically diverse lakes using Sentinel-3-derived trophic level index

An accurate estimation of trophic state of lakes with satellite remote sensing is a challenge due to the optical complexity and variability associated with inland waters. Match-up data from 393 sampling stations that has concurrent Sentinel-3 OLCI images were acquired across Wuhan lakes. Trophic Level Index (TLI) algorithms were developed within a global Optical Water Type (OWT) classification system. The performance of algorithms with limited training data gathered by using spectral similarity of highest Sowt was not improved compared with that on basis of no classification. In contrast, using spectral similarity of Sowt > 0.9 rather than the highest Sowt to group more training data with similar traits for each OWT can help build more robust algorithms, which performance is better than that on basis of no classification. Algorithm performance statistics of the test dataset for the stepwise multiple linear regression (SMLR) method were the following: Mean Absolute Error (MAE) = 5.56;Mean Absolute Percentage Error (MAPE) = 11.02 %;Root Mean Square Error (RMSE) = 7.24 and for the back propagation neural network on the basis of the Levenberg-Marquardt-Bayesian regularization algorithm (LMBR-BPNN) method MAE = 4.56;MAPE = 8.33 %;RMSE = 5.98. We detected 8 different OWTs (2,3,4,5,9,10,11,12) in Wuhan lakes and clear spatio-temporal patterns of the trophic state between 2018 and 2020.Our results revealed that the trophic state of Wuhan lakes did not decrease as expected during the COVID-19 lockdown period.

Evaluating NOx emissions and their effect on O3 production in Texas using TROPOMI NO2 and HCHO

The Tropospheric Monitoring Instrument (TROPOMI) on the Sentinel-5 Precursor (S5P) satellite is a valuable source of information to monitor the NOx emissions that adversely affect air quality. We conduct a series of experiments using a 4×4 km2 Comprehensive Air Quality Model with Extensions (CAMx) simulation during April–September 2019 in eastern Texas to evaluate the multiple challenges that arise from reconciling the NOx emissions in model simulations with TROPOMI. We find an increase in NO2 (+17 % in urban areas) when transitioning from the TROPOMI NO2 version 1.3 algorithm to the version 2.3.1 algorithm in eastern Texas, with the greatest difference (+25 %) in the city centers and smaller differences (+5 %) in less polluted areas. We find that lightningNOx emissions in the model simulation contribute up to 24 % of the column NO2 in the areas over the Gulf of Mexico and 8% in Texas urban areas. NOx emissions inventories, when using locally resolved inputs, agree with NOx emissions derived from TROPOMI NO2 version 2.3.1 to within 20 % in most circumstances, with a small NOx underestimate in Dallas–Fort Worth (-13 %) and Houston (-20 %). In the vicinity of large power plant plumes (e.g., Martin Lake and Limestone) we find larger disagreements, i.e., the satellite NO2 is consistently smaller by 40 %–60 % than the modeled NO2, which incorporates measured stack emissions. We find that TROPOMI is having difficulty distinguishingNO2 attributed to power plants from the background NO2 concentrations in Texas – an area with atmospheric conditions that cause short NO2 lifetimes. Second, the NOx/NO2 ratio in the model may be underestimated due to the 4 km grid cell size. To understand ozone formation regimes in the area, we combine NO2 column information with formaldehyde (HCHO) column information. We find modest low biases in the model relative to TROPOMI HCHO, with -9 % underestimate in eastern Texas and -21 % in areas of central Texas with lower biogenic volatile organic compound (VOC) emissions. Ozone formation regimes at the time of the early afternoon overpass are NOx limited almost everywhere in the domain, except along the Houston Ship Channel, near the Dallas/Fort Worth International airport, and in the presence of undiluted power plant plumes. There are likely NOx-saturated ozone formation conditions in the early morning hours that TROPOMI cannot observe and would be well-suited for analysis with NO2 and HCHO from the upcoming TEMPO (Tropospheric Emissions: Monitoring Pollution) mission. This study highlights that TROPOMI measurements offer a valuable means to validate emissions inventories and ozone formation regimes, with important limitations.

Study of the Water Environment Risk Assessment of the Upper Reaches of the Baiyangdian Lake, China

The risk assessment of water environments provides important references for water environment risk management. In this paper, the water environment risk of the upper rivers of the Baiyangdian Lake is assessed, considering both cumulative and sudden environmental risk. For the cumulative environmental risk assessment of the rivers, the characteristics of pollution transmissibility and accumulation in rivers was considered firstly. Furthermore, suggestions for the control of water environment pollution in the Baiyangdian Basin are given. The results indicate that the cumulative water environment risks of the Xiaoyi River—Dingzhou County, Xiaoyi River—Anguo County, Xiaoyi River—Boye County, and Xiaoyi River—Li County are high. The amount of fertilizer applied per unit of cultivated area, water quality, rate of water quality above the standard in water function zoning, and the ratio of environmental investment to gross domestic product (GDP) are important factors influencing the cumulative water environment risk. For sudden water environment assessments, the Xiaoyi River—Boye County is high. In the future, reducing the intensity of fertilizer application, strengthening the water quality control of the rivers, as well as upgrading the industry, should be carried out to protect the water environment in the Baiyangdian Basin.

The 5th Indonesian Society of Limnology (MLI) Congress and International Conference 2021

The 5th Indonesian Society of Limnology (MLI) Congress and International Conference 2021 is a biannual conference organized by the Indonesian Society of Limnology, with the theme is “Building synergies towards sustainable use of inland waters.” This year due to the COVID-19 pandemic, we hold the event virtually from 2nd to 3rd December. The objectives of this event are to (1) Connect, discuss, share and create a mutual network among communities from different backgrounds who are interested in inland waters ecosystem;(2) Disseminate science & technology and lessen the gap between scientific and common communities through fruitful discussion settings;(3) Underpin sustainable use and management of inland aquatic ecosystems.There were four keynotes speakers, four invited speakers, and 66 general presenters in the conference sessions. In total, 116 participants were registered and joined the conference. The first keynote speaker was Prof. Dr. Gadis Sri Haryani from the Research Center for Limnology and Water Resources, National Research and Innovation Agency of the Republic of Indonesia (BRIN), Indonesia, who presented research about Migratory freshwater fish in Indonesia: Threats and conservation efforts. The second presenter was Dr. Robert Walsh from the Australian Water Life, Australia, who presented research about Discover the world of Micro-invertebrates. The third keynote speaker was Dr. Khamla Inkhavilay from the National University of Laos, Lao PDR, who presented Persistent Organic Pollutants in Wetland of Mekong Basin. The fourth speaker was Dr. Kwanraree Joy Sirikanchana from the Chulabhorn Research Institute, Thailand, who presented Microbial Source Tracking and Quantitative Microbial Risk Assessment for Sustainable Water Pollution Management.In addition, the four invited speakers and 66 general presenters split into four rooms for parallel discussions which covered the latest research on inland water ecosystems, including;(1) Biotic resources, biodiversity, and conservation;(2) System Dynamic of inland waters;(3) Applied technology for the management and pollution control;(4) Modelling, system information, decision support tool, disaster risk reduction;(5) Management, policies, regulation, education, social, economy, and culture.We highly appreciate the generous support from Research Centre for Limnology-BRIN (Indonesia), Australian Water Life (Australia), Chulabhorn Research Institute (Thailand), National University of Laos (Lao PDR), Southeast Asian Limnological Network (SEALnet), Advisory Board, Steering and Organizing committee and all presenters and participants.List of Committees, Advisory Board, Steering Committee, Scientific Committee, Organizing Committee, Documentation, all photos are available in this pdf.

Six months in the Lhù'ààn Mân' (Kluane Lake) watershed: Autobiographical reflection on the benefits of an extended data collection campaign

Lhù'ààn Mân' is located in the southwest corner of Yukon Territory, tucked into the foot of Kluane Ranges of the St. Elias Mountains. The lake is situated on the traditional territory of the Kluane First Nation, Champagne and Aishihik First Nations, and the White River First Nation. The lake and its watershed are culturally significant and provide sources of fresh water, fish, land animals for hunting and trapping, berries, and lumber. Miller is a a PhD candidate in the Department of Geography at the University of Calgary working on an exploratory hydrology research project in the Lhù'ààn Mân' watershed. In May of 2016, Kaskawulsh Glacier retreat redirected the meltwater away from it. The event caused the volume of water to decrease significantly, leaving the areas of the river valley that were previously under water dry. Kaskawulsh Glacier runoff was the largest source of glacial water to the lake until then. By August, its level dropped nearly 2 m and has not refilled. This drastic change over a short time period drew a lot of attention and has raised questions in the academic and local communities about glacially-connected water resources in a changing climate.

Kluane Lake Research Station: Summer Field Season 2021

The 2021 summer field season at the Kluane Lake Research Station (KLRS) was 28 weeks long, from Mar 25 to Oct 6. During this time, KLRS supported almost 2,000 user days, of which 75% were represented by researchers. In total, KLRS welcomed researchers from 13 universities from Canada and the US, and 35 junior researchers (mostly graduate students). From Yukon, the station hosted two high school groups, the Yukon Conservation Corp and the Yukon Boys and Girls Club. Half of our users at the station this summer were visiting for the first time.