Apparent Seasonal Variation Research Articles

Spatio‐Temporal Characteristics and Variability of GNSS‐Derived Atmospheric Precipitable Water Vapor From 2010 to 2023 in Fujian Province, China

AbstractAtmospheric precipitable water vapor (PWV) is a crucial factor affecting precipitation and the atmospheric environment. To quantitatively investigate the spatio‐temporal distribution and characteristics of the PWV in Fujian, China, its diurnal and seasonal variations are analyzed based on the global navigation satellite system (GNSS) data from 2010 to 2023, ground meteorological observations, meteorological sounding data and ERA5 data. Moreover, the spatio‐temporal characteristics of the monthly PWV are assessed by using the empirical orthogonal function (EOF), the Mann‐Kendall test and the sliding t‐test. The results indicate that the ground‐based GNSS PWV data is able to reveal the distribution and variation of PWV over Fujian. Specifically, the diurnal distribution of the PWV varies remarkably with time, and the PWV in the eastern coastal areas is generally higher than in the western mountainous areas. The seasonal variation characteristics of the PWV are consistent with the atmospheric circulation variations, with the largest amount of PWV in summer, followed by spring, autumn and winter. Moreover, the EOF spatial modes show that the PWV distributions are different in the eastern coastal areas and inland mountainous areas. The oscillation intensity of the PWV strengthens from the northwest to the southeast, and the corresponding time series of the PWV displays apparent seasonal variations. The observed precipitation is inconsistent with the PWV and is more affected by local terrain and thermodynamic conditions. The Mann‐Kendall test and the sliding t‐test indicate that the PWV over Fujian has not undergone abrupt changes during the past 13 years, but there is a possibility of sudden changes in the future.

Machine Learning Driven Sensitivity Analysis of E3SM Land Model Parameters for Wetland Methane Emissions

AbstractMethane (CH4) is globally the second most critical greenhouse gas after carbon dioxide, contributing to 16%–25% of the observed atmospheric warming. Wetlands are the primary natural source of methane emissions globally. However, wetland methane emission estimates from biogeochemistry models contain considerable uncertainty. One of the main sources of this uncertainty arises from the numerous uncertain model parameters within various physical, biological, and chemical processes that influence methane production, oxidation, and transport. Sensitivity Analysis (SA) can help identify critical parameters for methane emission and achieve reduced biases and uncertainties in future projections. This study performs SA for 19 selected parameters responsible for critical biogeochemical processes in the methane module of the Energy Exascale Earth System Model (E3SM) land model (ELM). The impact of these parameters on various CH4 fluxes is examined at 14 FLUXNET‐ CH4 sites with diverse vegetation types. Given the extensive number of model simulations needed for global variance‐based SA, we employ a machine learning (ML) algorithm to emulate the complex behavior of ELM methane biogeochemistry. We found that parameters linked to CH4 production and diffusion generally present the highest sensitivities despite apparent seasonal variation. Comparing simulated emissions from perturbed parameter sets against FLUXNET‐CH4 observations revealed that better performances can be achieved at each site compared to the default parameter values. This presents a scope for further improving simulated emissions using parameter calibration with advanced optimization techniques.

Seasonal Variation in Detection of Haemosporidia in a Bird Community: A Comparison of Nested PCR and Microscopy.

In a 2-yr study on prevalence of Haemosporidia in an avian community in Ithaca, New York, USA, we tested the hypothesis that apparent seasonal variation in prevalence is influenced by the detection protocol. We confirmed a higher detection of Haemosporidia using a molecular diagnosis technique (PCR) than by microscopy; this further increased when the PCR test was triplicated. Microscopic examination and PCR techniques have different specificity and sensitivity and therefore different probabilities of detecting hemoparasites. Birds with chronic infections or sampled during winter often have very low parasitemia, and such infections may be missed by microscopy but detected by PCR. Haemosporidian prevalence was higher during the breeding season than during the nonbreeding season regardless of the method used. Detection of Leucocytozoon spp. infection from blood smears using microscopy was challenging.

Characteristics and sources of atmospheric ammonia at the SORPES station in the western Yangtze river delta of China

Ammonia (NH3) is an important air pollutant with crucial impacts on air quality, ecosystems and climate change. However, NH3 is not included in routine air quality monitoring and the availability of long-term NH3 measurements is still limited, resulting in large uncertainties in our knowledge of the spatial distribution and sources of NH3. Here we performed 1 year (March 2021–February 2022) of atmospheric NH3 measurements at a regional background station, the Station for Observing Regional Processes of the Earth System (SORPES) in the western Yangtze River Delta of China. We found that the annual mean NH3 concentration was 12.2 ± 4.6 ppb and exhibited apparent seasonal variations, with a maximum in June and a minimum in February, influenced by agricultural activities, air temperature, gas-particle partitioning and precipitation. Moreover, air temperature and absolute humidity correlated well with NH3, indicating that they are important factors in influencing NH3 levels. The diurnal variation of NH3 showed a single peak in the morning and higher concentrations during the day. In spring and autumn, the NH3 morning peak can be attributed to dew evaporation. The air mass backward trajectory, local wind direction and velocity analysis suggested that NH3 was influenced by both local emissions and regional transport from nearby cities. During the COVID-19 lockdown, a strong reduction of NOx (−77%) and a weak reduction of NH3 (−14%) were observed compared to the pre-lockdown, highlighting that traffic emissions have a minor impact on NH3 at the SORPES station. Our results provide more insights into the characteristics and sources of atmospheric NH3 in background regions influenced by mixed air pollution plumes.

Observations and Modeling of Gaseous Nitrated Phenols in Urban Beijing: Insights From Seasonal Comparison and Budget Analysis

AbstractNitrated phenols (NPs) are critical components of brown carbon with climate effects and threaten human health and ecosystems. Early studies mainly focus on particulate NPs, while the sources and impacts of gas‐phase NPs remain less known. This study observed 17 kinds of gaseous NPs in urban Beijing during winter and summer by nitrate‐based long‐time‐of‐flight chemical ionization mass spectrometer (NO3−‐LToF‐CIMS). NPs have an apparent seasonal variation and various diurnal patterns among different species. Source apportionment indicates that secondary productions are the major sources of NPs, besides minor contributions from coal burning and regional industrial emissions. As shown by the observation and box modeling, NO3‐initiated nocturnal oxidation and OH‐driven photochemistry are the secondary sources of NPs. In both seasons, photolysis constitutes the dominating removal pathway of NPs. We determined the observation‐constrained photolysis frequency of typical NPs (i.e., C6H5NO3, C7H7NO3, C6H4N2O5, and C7H6N2O5), ranging from 1.75% to 7.5% of jNO2. Budget analysis reveals that benzaldehyde produced by styrene oxidation is a critical but overlooked precursor of C6H5NO3, and xylene is an essential precursor for C7H7NO3. Modeling results further show that the photolysis of total NPs produces significant amounts of HONO in summer, making noticeable contributions to atmospheric oxidation capacity. This study contributes to a better understanding of the budget of gaseous NPs in the urban atmosphere and provides insights into mitigating NPs‐induced secondary pollution.

Analytical Study of a Case Series Of Vancomycin Associated Adverse Drug Reactions In Paediatric Population at a Tertiary Care Hospital: A Brief Report

Background: Red man syndrome (RMS) is frequently reported from pediatric ward in patients receiving vancomycin, at the medical store of SGH, Pune. Though common in pediatric patients, not all patients receiving vancomycin developed Red man syndrome. Hence, this study was done to analyse the demographic, pathophysiological, and pharmacological aspects of the subject who experience adverse drug reactions with vancomycin and to determine if this predisposition is associated with any of these factors.
 Methods: All adverse drug reactions (ADR) to injection vancomycin in the pediatric ward that were reported from April 2018 - January 2022 were included. Controls were a similar number of randomly selected pediatric cases from the same ward who had received Intravenous vancomycin during the same period but did not experience the adverse drug reactions
 Results: The mean age was 29.91 ± 34.87 months in subjects who experienced ADR and 57.37 ± 41.58 months, in non-ADR group (p=0.0286). 37.4% were infants, 29.69% toddlers in ADR Group. Seventy four percent of patients who manifested with ADR were below age of 3 compared to barely 38% in controls (p=0.03). 66.6% were malnourished in the ADR group compared to 27.6% in controls (p=0.007). There was no association between the ADR and ethnicity, religion, gender, diagnosis, co-morbidities, co-administered drugs, or administered dose of vancomycin among the children. There was no apparent seasonal variation in occurrence of the ADR.
 Conclusion: RMS is more common in paediatric population than adults and is usually uneventful. Around 75% of the reactions occur within first 4 days of start of Vancomycin and usually occurs within 30 min of the preceding dose. Younger age groups (infants) and malnourishment were the two factors significantly associated with occurrence of RMS. We may also consider using lower than conventional doses and much slower infusions in such at-risk population.

Foodborne protozoan parasites in fresh mussels and oysters purchased at retail in Canada

Studies worldwide have reported the presence of protozoan parasites in a variety of commercial bivalve shellfish. The uptake of these parasites by shellfish occurs during filter feeding in faecally-contaminated waters. The objective of the present study was to determine the prevalence of Giardia, Cryptosporidium and Toxoplasma in fresh, live shellfish purchased in three Canadian provinces as part of the retail surveillance activities led by FoodNet Canada (Public Health Agency of Canada). Packages containing mussels (n = 253) or oysters (n = 130) were purchased at grocery stores in FoodNet Canada sentinel sites on a biweekly basis throughout 2018 and 2019, and shipped in coolers to Health Canada for testing. A small number of packages were not tested due to insufficient quantity or poor quality. Following DNA extraction from homogenized, pooled tissues, nested PCR and DNA sequencing were used to detect parasite-specific sequences. Epifluorescence microscopy was used to confirm the presence of intact cysts and oocysts in sequence-confirmed PCR-positive samples. Giardia duodenalis DNA was present in 2.4 % of 247 packages of mussels and 4.0 % of 125 packages of oysters, while Cryptosporidium parvum DNA was present in 5.3 % of 247 packages of mussels and 7.2 % of 125 packages of oysters. Toxoplasma gondii DNA was only found in mussels in 2018 (1.6 % of 249 packages). Parasite DNA was detected in shellfish purchased in all three Canadian provinces sampled, and there was no apparent seasonal variation in prevalence. While the present study did not test for viability, parasites are known to survive for long periods in the marine environment, and these findings suggest that there is a risk of infection, especially when shellfish are consumed raw.

Isotope provenance of AMD and treatment options for large, abandoned mines: A case study of the abandoned Dashu pyrite mine, Southwest China

Discharge of acid mine drainage (AMD) along with heavy metals mobilization is a critical environmental concern. An urgent need is to manage or treat AMD in the minefield effectively. To this end, based on a hydrogeological investigation, the d-T (deuterium excess parameter-Tritium content) technique was adopted to trace the recharge, runoff, and discharge of AMD in the abandoned Dashu pyrite mine in China. The results reveal that AMD in the minefield originates from local precipitation and shallow groundwater and exhibits apparent seasonal runoff variations. The AMD is associated with shallow groundwater from the top of the Quaternary platform on the axis of the Dashu anticline, and protons could originate from the pyrite oxidation. Therefore, an engineering practice to purify the AMD is combined with (1) water diversion to stop AMD formation and blockage of the AMD outlets. (2) Acceleration of Fe(II) oxidation through aeration promotes the precipitation of Fe-oxide and hydroxide. (3) Neutralization of AMD using Karst water from the Maokou Formation (P2m). This study provides a new research idea and tracing method for improving hydrogeological surveys and effectively handling environmental problems related to AMD of abandoned mines.

Comparative analysis of four types of mesoscale eddies in the North Pacific Subtropical Countercurrent region - part II seasonal variation

The North Pacific Subtropical Countercurrent area (STCC) is high in mesoscale eddy activities. According to the rotation direction of the eddy flow field and the sign of temperature anomaly within the eddy, they can be divided into four categories: cyclonic cold-core eddy (CCE), anticyclonic warm-core eddy (AWE), cyclonic warm-core eddy (CWE) and anticyclonic cold-core eddy (ACE). CCE and AWE are called normal eddies, and CWE and ACE are named abnormal eddies. Based on the OFES data and vector geometry automatic detection method, we find that at the sea surface, the maximum monthly number of the CCE, AWE, CWE, and ACE occurs in December (765.70 ± 52.05), January (688.20 ± 82.53), August (373.40 ± 43.09) and August (533.00 ± 56.92), respectively. The number of normal eddies is more in winter and spring, and less in summer and autumn, while abnormal eddies have the opposite distribution. The maximum rotation velocity of the four types of eddies appears in June (11.71 ± 0.75 cm/s), June (12.24 ± 0.86 cm/s), May (10.63 ± 0.99 cm/s) and June (9.97 ± 0.91 cm/s), which is fast in winter and spring. The moving speed of the four types of eddies is almost similar (about 10 ~ 11 cm/s). The amplitude of normal and abnormal eddies is both high in summer and autumn, and low in winter and spring, with larger amplitudes in normal than abnormal eddies. The eccentricity (defined as the eccentricity of the ellipse obtained by fitting the eddy boundary) of the four types of eddies is also close to each other, and their variation ranges from 0.7 to 0.8, with no apparent seasonal variation. The vertical penetration depth, which has no significant seasonal difference, is 675.13 ± 67.50 m in cyclonic eddies (CCE and CWE), which is deeper than that 622.32 ± 81.85 m in anticyclonic eddies (ACE and AWE). In addition, increasing the defined temperature threshold for abnormal eddies can significantly reduce their numbers but does not change their seasonal variation trend.

Observation of Near-Inertial Internal Gravity Waves in the Southern South China Sea

Two sets of more than 850 days of mooring records and satellite altimeter data are used to explore the features and spatiotemporal evolution of near-inertial waves (NIWs) near Nansha Island in the southern South China Sea (SCS). The observed NIWs are dominated by clockwise (downward energy propagation) motions and show a clear blue shift with a distinct peak frequency of 1.09 f during two large NIW events. The near-inertial kinetic energy (NIKE) is primarily concentrated in the upper layer and radiated downward. The largest value of depth-integrated NIKE reaches 3.5 KJ/m2. Besides, the NIWs are dominated by the first three modes, which account for 80% of the total NIKE. Moreover, the depth-integrated NIKE exhibits an apparent seasonal variation, with the largest NIKE in winter, which is almost three times larger than that in other seasons. Every large NIKE event is attributed to the passage of storms and is dominated by mode-2 NIWs. The dominance of the mode-2 NIWs is likely caused by the interaction between NIWs and mesoscale eddies.

Seasonal Variation in Gravity Wave Momentum and Heat Fluxes in the Mesopause Region Observed by Sodium Lidar

AbstractThe seasonal variations in gravity wave (GW) vertical fluxes of zonal momentum and heat in the mesopause region are calculated using nearly 10 years (from 2012 to 2021) of temperature and wind observations by a narrowband sodium lidar located in Hefei, China (32°N, 117°E). Except in summer, the GW zonal momentum fluxes are mostly westward, with ∼80% contributed by the short‐period (10 min–1 hr) GWs, and anticorrelate with the eastward zonal wind. The mean westward zonal momentum fluxes in spring and winter are −2.55 and −1.78 m2/s2, respectively, which are much stronger than −0.98 m2/s2 in fall. The momentum flux in summer is primarily eastward, dominated by long‐period (1–16 hr) GWs. These seasonal variations in zonal momentum fluxes are mainly due to the filtering of GWs by the mean background wind at lower altitudes. The annual mean zonal momentum flux is westward with a value of −1.08 m2/s2. The calculated acceleration from flux divergence is westward below 93 km, opposite to the eastward mean zonal wind. The heat flux below 94 km is downward throughout the year, with no apparent seasonal variation. The annual mean heat flux is primarily downward, with a cooling rate of ∼−35 K/day between 87 and 95 km.

Spatiotemporal Heterogeneity in Precipitation over China and Its Connections with Large-Scale Climate Oscillations—A Moisture Budget Perspective

Abstract Climate change can lead to variations in the probability distribution of precipitation. In this study, quantile regression (QR) is undertaken to identify the quantile trends in precipitation over China and to examine the quantile effects of various climate oscillations on precipitation. The results show that the quantile trends show apparent seasonal variations, with a greater number of stations showing trends in winter (especially at quantile levels ≥ 0.5), and larger average magnitudes of trends at nearly all quantile levels in summer. The effects of El Niño–Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Pacific decadal oscillation (PDO) exhibit evident variations with respect to the quantile level. Spatial clusters are subsequently identified based on the quantile trends, and the individual and combined effects from the teleconnection patterns are further investigated from the perspective of moisture budget. Seven spatial clusters with distinct seasonal quantile trends can be identified; three of them are located in southeastern China and are characterized by increasing trends in summer and winter precipitation. Summer precipitation over this region is positively influenced by ENSO and negatively influenced by NAO, with the former affecting both the dynamic and thermodynamic components of vertically integrated moisture divergence and the latter affecting only the dynamic component. The interaction effect of ENSO and NAO on summer precipitation anomalies in months that are extremely wetter than normal is statistically significant. In comparison, winter precipitation in this region is under the positive influence of ENSO and NAO and the negative influence of PDO; the effect of ENSO on moisture convergence can be mainly attributed to its dynamic component.

Nutrient levels and prokaryotes affect viral communities in plateau lakes

Viruses are the most abundant organisms in aquatic environments. Recent advances of viral metagenomic have greatly expanded our understanding of aquatic viral communities. However, little is known about the difference of viral communities and driving factors in freshwater lake. This study seeks to understand the spatio-temporal variation, differences, and driving factors of viral communities in two plateau lakes (Dianchi and Fuxian Lakes) with significant nutritional differences. The viral communities exhibited apparent seasonal variation in Dianchi Lake, while seasonal influences on the viral communities were greater than location-based influences. Two-thirds of all detected viral taxa were shared in two lakes, but there was variation in the composition of viral communities. Correlations between prokaryotic communities, environmental factors and viral communities were analyzed. The nutrients, chlorophyll a were primarily environmental parameters affecting viral communities, and the prokaryotic community was significantly correlated with the viral community. In addition, several viruses infecting humans were identified in two lakes, with the most abundant being Herpesviridae and Poxviridae. Overall, these findings provide information on the dynamics, composition, and differences of viral and prokaryotic communities in plateau lakes with different nutrient levels. These results suggest that nutritional levels and prokaryotic communities could play an important role in shaping viral communities in freshwater lakes.

Seasonal variations and the influence of COVID-19 pandemic on hemoglobin A1c, glycoalbumin, and low-density lipoprotein cholesterol.

AimThe purpose of the study was to investigate seasonal variations in HbA1c, GA and LDL-C and to examine the effects of the COVID-19 pandemic on these variations and on glycemic and lipid control themselves in patients with type 2 diabetes.Patients and methodsThe subjects were outpatients with type 2 diabetes who had received standard treatment for glycemic control for more than 3 years. Data for patients who visited our hospital from January 2021 to March 2021 were retrospectively investigated based on electronic medical records.ResultsHbA1c showed seasonal variation (high in winter–spring and low in summer–autumn), and this was similar during the COVID-19 pandemic. However, the mean HbA1c over 1 year was significantly elevated during the COVID-19 pandemic (7.53 ± 1.02% in 2020) compared with the previous 2 years: (7.34 ± 0.91 in 2018, 7.39 ± 0.93 in 2019; 2020 vs. 2018; 0.19%, P < 0.001; 2020 vs. 2019; 0.14%, P = 0.0013) and the difference was larger in winter. GA showed no apparent seasonal variation, but mean GA during the COVID-19 pandemic was elevated compared with earlier years (2020 vs. 2018, P < 0.001; 2020 vs. 2019, P < 0.001). LDL-C did not show apparent seasonal variation and was unaffected by COVID-19 pandemic.ConclusionThe COVID-19 pandemic influenced mean HbA1c and GA levels over 1 year, but did not affect seasonal variations, while LDL-C was not affected by COVID-19. Observation of these levels over a longer period is warranted to determine the longer-term influence of the COVID-19 pandemic.

Shifting of dissolved organic matter components and sources in precipitation into an intensified anthropogenic influenced embayment: Interpretation from spectral characteristics and dual stable isotopes

Dissolved organic matter (DOM) is a ubiquitous group of organic compounds in rainwater that contributes to DOM pools and plays a vital role in the marine biogeochemical cycle. Here, we presented the rainwater DOM components and sources attribution (in δ13C-DOMSPE and δ15N-DOMSPE perspective) to an intensified anthropogenic influenced embayment, and discussed the biogeological effects of atmospheric DOM deposition. The results showed an apparent seasonal variation in the DOM concentration dominated by precipitation. Moreover, the excitation-emission matrix spectroscopy coupled a parallel factor analysis (PARAFAC) results revealed that five fluorescent components (C1-C5) of the rainwater DOM. C1 and C5 are protein-like DOM components and derived from biogenic emissions. The fluorescence intensity of C1 and C5 were significantly higher in the wet season, whereas C2 and C3, which are humic-like substances with higher molecular weights and aromatization, were mainly derived from fossil fuel combustion. The δ13C-DOMSPE and δ15N-DOMSPE results indicated that fossil fuel contributed approximately 80% of the DOM in the precipitation in the dry seasons, whereas the marine emission contribution of DOM was higher in the wet seasons due to the influence of air masses originating from the South China Sea. However, the maritime emissions only contributed 4% to the rainwater DOM. The deposition fluxes of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) were 799 mmol·C·m˗2·yr˗1 and 46 mmol·N·m˗2·yr˗1, respectively, and they played a substantial role for the DOM input flux of Daya Bay (28% of DOC and 12% of DON, respectively). Overall, our results suggest that atmospheric wet deposition represents a potentially critical source of organic carbon and nitrogen for coastal waters, particularly in intensified anthropogenically influenced embayments characterized by substantial monsoon shifts between seasons.

Hospital-acquired pneumonia - no apparent seasonal variation: a single institution study

Unlike the clear seasonal differences that have been recorded for certain respiratory infectious illnesses, variation in hospital-acquired pneumonia (HAP) rates by time of year has not been thoroughly investigated. The primary aim of this study was to determine whether HAP rates fluctuate during the year at the University Medical Center (UMC) in Lubbock, Texas. An internal data source maintained by UMC’s Infection Prevention &amp; Control Office called MedMined that builds an algorithm using nosocomial infection markers (NIMs) was used to track HAP rates. The NIMs are microbiology results from various sample sources, including urine, stool, wound, respiratory secretions, and other, that provide a better understanding of a patient’s infection risk and status. MedMined respiratory NIMs data on quarterly scorecards from January 2015 to March 2020 were evaluated using one-way analysis of variance (ANOVA) and subsequently stratified to the departmental level (e.g., MICU, SICU, etc.) followed by a repeat one-way ANOVA for each of the selected departments. Analysis of hospital-wide and selected UMC hospital department respiratory NIMs data revealed no statistically significant difference in respiratory NIM rate by time of year (P = 0.25). Therefore, there is no apparent variation in HAP rates at UMC with respect to time of year either on a hospital-wide or a selected departmental level. Analysis of a national dataset might help determine whether this finding occurs at other institutions.&#x0D; &#x0D; Key words: hospital-acquired pneumonia, intensive care units, seasons

Unravelling the spatiotemporal variation of pCO2 in low order streams: Linkages to land use and stream order

Headwater streams make the majority of cumulative stream length in a river basin, carbon dioxide (CO2) emission from headwater (low order) streams is thus an essential component. Anthropogenic activities in headwater areas such as land use change and land use practices can strongly modify terrestrial carbon and nutrient input, which could affect the level of partial pressure of dissolved carbon dioxide (pCO2) and CO2 degassing from streams. However, there are large uncertainties in estimates due to the lack of data in subtropical rivers of rapidly developing rural regions. The spatiotemporal variation and driving factors of the pCO2 and CO2 degassing from low-order streams remain to be explored. In this study, we assess multi-spatial scale effects of land use on pCO2 dynamics in seven headwater tributary rivers in Central China during 2016, 2017 and 2018 in rainy and dry seasons. Our results reveal that the stream pCO2 level consistently increases as the stream order increases from 1 to 3 under apparent seasonal variations. Riverine pCO2 is positively related to the percentage of urban land and cropland surrounding the river segments, but is negatively related to the percentage of forest land. The stream pCO2 is more closely correlated with the 1000 and 2000 m diameters of circular buffers at upstream sampling sites than the circular buffers with 100 and 500 m diameters. There exist significant relationships of pCO2 with the concentrations of TN, TP, DO, and DOC in the low-order streams. The partial redundancy analysis quantifies the relative importance of anthropogenic land uses, natural factors and water chemical variables in mediating stream pCO2, showing that influences of anthropogenic land uses (urban and cropland) on pCO2 decrease, with a percentage role of 34%, 14%, and 4% in the 1st-, 2nd- and 3rd-order streams, respectively. The impact of nutrients on pCO2, however, increases as the stream order increases. Urban influence on stream pCO2 also decreases as stream order increases. Our study highlights the effect of land use/land cover types and stream order on riverine pCO2 and provides new insight into estimating CO2 emission in headwater streams. Future studies are needed on the linkage between riverine CO2 degassing and stream orders under changing land use conditions.

Interferometric coherence and seasonal deformation characteristics analysis of saline soil based on Sentinel-1A time series imagery

Affected by the natural environmental and human activity factors, significant seasonal differences appear on the regional scattering characteristic and ground deformation of saline soil. Interferometric decorrelation due to season replacement limits the conventional multi-temporal interferometric synthetic aperture radar (MT-InSAR) technique and its application in such areas. To extend the monitoring capability in the salt desert area, we select a vast basin of saline soil around Howz-e-Soltan Salt Lake of Iran as the study area and present an improved MT-InSAR for experimental research. Based on 131 C-band Sentinel-1A images collected between October 2014 to July 2020,1896 refined interferograms in total are selected from all interfero-gram candidates. Interferometric coherence analysis shows that the coherence in the saline soil area has an apparent seasonal variation, and the soil moisture affected by the precipitation may be the main factor that leads to the seasonal variation. Subsequently, the deformation characteristics of saline soil under different environmental conditions and human activity factors are compared and analyzed in detail. Related deformation mechanisms of different saline soil types are initially revealed by combining interferometric coherence, meteorological data, and engineering geological characteristics of saline soil. Related results would provide reference for the large-scale infrastructure construction engineering in similar saline soil areas.

First evaluation of iron and manganese concentrations in coastal aquaculture water in Giao Thuy district, Nam Dinh province

Aquaculture in the coastal zone has contributed significantly to economic development in Giao Thuy district, Nam Dinh province. Therefore, water quality for aquaculture plays a vital role in sustainable aquaculture production. In this paper, iron (Fe) and manganese (Mn) concentrations in aquaculture coastal water of Giao Thuy district were analyzed during the rainy season (September 2017, August 2018) and dry season at low tide. The results showed that Fe concentration varied from 0.09 mg/L (at VT5) to 2.42 mg/L (at VT4), averaging 1.12 ± 0.71 mg/L, which exceeded the critical value of the national technical regulation on marine water quality in Vietnam for coastal aquaculture water (QCVN 10:2015/BTNMT) from 1.5 times (at VT4) to 3.0 times (at VT1). Mn concentrations ranged from 0.02 mg/L (at VT9) to 0.10 mg/L (at VT1), averaging 0.05 ± 0.02 mg/L, which was lower than the critical value in the QCVN 10:2015/BTNMT. The results showed that no apparent seasonal variation was observed for both Fe and Mn concentrations. In the dry season, the Fe and Mn concentrations averaged 1.10 mg/L and 0.05 mg/L respectively, whereas they were 1.15 mg/L and 0.05 mg/L in the rainy season. The monitoring results showed that Fe was polluted in the study area and may affect aquaculture productivity. Therefore, helpful measures should be taken to minimize Fe pollution to protect water quality and develop sustainable aquaculture in Giao Thuy district, Nam Dinh province.

Epidemic situation and diagnosis of imported malaria before and after malaria elimination in Nanjing City, Jiangsu Province

To analyze the epidemiological characteristics and diagnosis of imported malaria before and after malaria elimination in Nanjing City of Jiangsu Province, so as to provide the scientific evidence for formulating the malaria control strategy after malaria elimination. Data pertaining to the epidemic situation and individual investigation of malaria in Nanjing City before (from 2012 to 2016) and after malaria elimination (from 2017 to 2020) were captured from the National Notifiable Communicable Disease Reporting System and the Information System for Parasitic Diseases Control and Prevention and were analyzed statistically. A total of 178 malaria cases were reported in Nanjing City from 2012 to 2020, and all were imported cases. There were 99 malaria cases reported before malaria elimination in Nanjing City, including 78 cases with Plasmodium falciparum malaria (78.79%), 5 cases with P. vivax malaria (5.05%), 10 cases with P. ovale malaria (10.10%), 3 cases with P. malariae malaria (3.03%) and 3 cases with mixed infections (3.03%), and 79 malaria cases reported after elimination, including 63 cases with P. falciparum malaria (79.75%), 5 cases with P. vivax malaria (6.33%), 9 cases with P. ovale malaria (11.39%), 2 cases with P. malariae malaria (2.53%). There was no significant difference in the proportion of each type of malaria cases in Nanjing City before and after malaria elimination (χ2 =2.400, P > 0.05). Malaria cases mainly acquired Plasmodium infections in African regions, and no significant difference was seen in the proportion of malaria cases returning to Nanjing City from African countries before and after malaria elimination (χ2 = 0.093, P > 0.05). The number of malaria cases peaked in Nanjing City in January and during the period from May to July before elimination, and there was no apparent seasonal variation in the distribution of malaria cases after elimination. The proportion of malaria cases living in Nanjing City was significantly greater after malaria elimination than before elimination (72.15% vs. 55.56%; χ2 = 5.187, P = 0.023). The proportions of businessmen and international students were both 5.05% before malaria elimination, and increased to 15.19% and 13.92% after elimination, respectively (χ2 = 5.229 and 4.229, both P values < 0.05). The percentage of definitive diagnosis of malaria at initial diagnosis was 18.75% in county-level hospitals before malaria elimination and increased to 61.11% after elimination (χ2 = 6.275, P = 0.012), while the proportion of malaria cases with definitive diagnoses in county-level hospitals was 4.04% before malaria elimination and increased to 13.92% after elimination (χ2 = 5.562, P = 0.018). During the period from 2012 to 2020, the proportion of malaria cases with definitive diagnoses within 1 to 3 days post-admission increased from 27.27% in Nanjing City before malaria elimination to 45.57% after elimination (χ2 = 6.433, P = 0.011). The epidemic situation of imported malaria remains serious in Nanjing City during the post-elimination stage, and malaria parasite infections predominantly occur in African regions. In addition, there are changes in regional and occupational distributions of malaria cases and the diagnostic capability of malaria increases in county-level hospitals in Nanjing City after malaria elimination. Further improvements in the malaria surveillance system and the diagnostic and treatment capability of malaria in medical institutions at each level are required to consolidate malaria elimination achievements in Nanjing City.