Spatiotemporal Variations of Radon Concentration in the Atmosphere of Zhijindong Cave (China)

Ensuring high air quality in the atmosphere of Zhijindong Cave is essential, for it is one of the most scenic in Asia and has received millions of tourists each year. Radon, as the most important radioactive carcinogen, is a priority and has been measured since just after its opening. However, an artificial exit was opened in 2002, and it is still unclear what the influence of that has been on the radon concentration in the cave atmosphere. In this study, we use RAD7 to monitor the spatiotemporal variations of radon concentration in the atmosphere of Zhijindong Cave for a whole year. The results show that radon concentration is generally higher in the hot season and lower in the cold season, and both with a distinct spatial differences. The highest measured radon concentration is 1691 Bq/m3, which is lower compared with the previous study. The reduced radon concentration could be caused by the strengthened cave ventilation due to the artificial exit. The temporal variation of radon concentration is related to the outside temperature change, while the spatial variation is mostly related to the different cave layers. The effective dose is negligible for tourists, but can be as high as 9.7 mSv for tour guides and 22.6 mSv for photographers.

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Application of a Fusion Method for Gas and Particle Air Pollutants between Observational Data and Chemical Transport Model Simulations Over the Contiguous United States for 2005–2014

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16183314 ◽

2019 ◽

Vol 16 (18) ◽

pp. 3314

Author(s):

Niru Senthilkumar ◽

Mark Gilfether ◽

Francesca Metcalf ◽

Armistead G. Russell ◽

James A. Mulholland ◽

...

Keyword(s):

United States ◽

Air Quality ◽

Spatial Variation ◽

Temporal Variation ◽

Observational Data ◽

Transport Model ◽

Chemical Transport ◽

Daily Basis ◽

Quality Data ◽

Chemical Transport Model

Accurate spatiotemporal air quality data are critical for use in assessment of regulatory effectiveness and for exposure assessment in health studies. A number of data fusion methods have been developed to combine observational data and chemical transport model (CTM) results. Our approach focuses on preserving the temporal variation provided by observational data while deriving the spatial variation from the community multiscale air quality (CMAQ) simulations, a type of CTM. Here we show the results of fusing regulatory monitoring observational data with 12 km resolution CTM simulation results for 12 pollutants (CO, NOx, NO2, SO2, O3, PM2.5, PM10, NO3−, NH4+, EC, OC, SO42−) over the contiguous United States on a daily basis for a period of ten years (2005–2014). An annual mean regression between the CTM simulations and observational data is used to estimate the average spatial fields, and spatial interpolation of observations normalized by predicted annual average is used to provide the daily variation. Results match the temporal variation well (R2 values ranging from 0.84–0.98 across pollutants) and the spatial variation less well (R2 values 0.42–0.94). Ten-fold cross validation shows normalized root mean square error values of 60% or less and spatiotemporal R2 values of 0.4 or more for all pollutants except SO2.

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Spatial and temporal variation of 13C-signature of methane emitted by a temperate mire ecosystem

10.5194/egusphere-egu21-12559 ◽

2021 ◽

Author(s):

Janne Rinne ◽

Patryk Łakomiec ◽

Patrik Vestin ◽

Per Weslien ◽

Julia Kelly ◽

...

Keyword(s):

Spatial Variation ◽

Temporal Variation ◽

Methane Emission ◽

Trophic Status ◽

Emission Rate ◽

Temporal Behavior ◽

Emission Rates ◽

Spatial Differences ◽

Mire Ecosystem ◽

Methane Emission Rate

The net methane emission of any mire ecosystem results from a combination of biological and physical processes, including methane production by archaea, methane consumption by bacteria, and transport of methane from peat to the atmosphere. The complexity of spatial and temporal behavior of methane emission is connected to these.13C-signature of emitted methane offers us a further constraint to evaluate our hypothesis on the processes leading to the variation of methane emission rates. For example, assuming the spatial variation in methane emission rate at microtopographic scale is due to variation in trophic status or variation in methane consumption, will lead to differences in the relation of methane emission rate and its&#160;13C-signature, expressed as &#948;13C.We have measured the methane emission rates and &#948;13C of emitted methane by six automated chambers at a poor fen ecosystem over two growing seasons. The measurements were conducted at Mycklemossen mire (58&#176;21'N 12&#176;10'E, 80m a.s.l.), Sweden, during 2019-2020. In addition, we measured atmospheric surface layer methane mixing ratios and &#948;13C to obtain larger scale 13C-signatures by the nocturnal boundary-layer accumulation (NBL) approach. All &#948;13C-signatures were derived using the Keeling-plot approach.The collected data shows spatial differences of up to 10-15 &#8240; in 10-day averages of &#948;13C-signatures between different chamber locations. Temporal variations of 10-day average &#948;13C-signatures from most chamber locations reached over 5 &#8240;, while the temporal variation of NBL derived &#948;13C-signature was slightly lower.The observed spatial variation in the &#948;13C-signature was somewhat systematic, indicating, especially in the middle of the summers, the main control of spatial variation of methane emission to be the trophic status. The temporal changes, measured at different locations, indicate spatial differences in the temporal dynamics at the microtopographic scale. The temporal behavior of larger scale NBL &#948;13C-signature does not fully correspond to the behavior of the chamber derived average &#948;13C-signature.

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The Measurements of Natural Radioactivity, (Radon and Gamma concentrations), around the old fertilizer factory in Basrah/Iraq

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v7i1.6955 ◽

2015 ◽

Vol 7 (1) ◽

pp. 1324-1335

Author(s):

Jabbar H. Jebur

Keyword(s):

Effective Dose ◽

Radon Concentration ◽

Gamma Ray ◽

Annual Effective Dose ◽

Track Detector ◽

Exhalation Rate ◽

Hazard Indices ◽

Radium Equivalent ◽

Passive Technique ◽

Radium Activity

Radon concentration, exhalation rate, annual effective dose, radium activity, thorium, uranium potassium and radium equivalent have been measured in the present investigation for soil in the area around the old fertilizer factory in southern of Basrah Governorate. The measurements based on CR39 track detector for passive method, RAD7 for active method and NaI(Tl) for gamma concentration measurements. Average values for radon concentration in soil were 112.04Â±10.76 Bq/m3 using passive technique and 104.56Â±6.05 Bq/m3 using RAD7. From the result of the passive technique, area and mass exhalation rates and the annual effective dose were calculated. Gamma ray spectroscopy for the soil samples were performed and found that the average concentrations of 226Ra, 232Th and 40K were 50.89 Bq/kg, 21.74 Bq/kg and 640.4 Bq/kg respectively. Gamma ray hazard indices were calculated and found they are within the world average.

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Spatial and Temporal Variation in Microbial Diversity and Community Structure in a Contaminated Mangrove Wetland

Applied Sciences ◽

10.3390/app10175850 ◽

2020 ◽

Vol 10 (17) ◽

pp. 5850

Author(s):

Jiaojiao Ma ◽

Ting Zhou ◽

Chunyu Xu ◽

Dawen Shen ◽

Songjun Xu ◽

...

Keyword(s):

Community Structure ◽

Spatial Variation ◽

Temporal Variation ◽

Bacterial Diversity ◽

Diversity Index ◽

Total Carbon ◽

Spatial And Temporal Variation ◽

Rrna Gene ◽

Mangrove Wetland ◽

Mangrove Soils

Field and laboratory investigations were conducted to characterize bacterial diversity and community structure in a badly contaminated mangrove wetland adjacent to the metropolitan area of a megacity in subtropical China. Next-generation sequencing technique was used for sequencing the V4–V5 region of the 16s rRNA gene on the Illumina system. Collectively, Proteobacteria, Chloroflexi, Planctomycetes, Actinobacteria and Bacteroidetes were the predominant phyla identified in the investigated soils. A significant spatial variation in bacterial diversity and community structure was observed for the investigated mangrove soils. Heavy metal pollution played a key role in reducing the bacterial diversity. The spatial variation in soil-borne heavy metals shaped the spatial variation in bacterial diversity and community structure in the study area. Other environmental factors such as total carbon and total nitrogen in the soils that are affected by seasonal change in temperature could also influence the bacterial abundance, diversity and community structure though the temporal variation was relatively weaker, as compared to spatial variation. The bacterial diversity index was lower in the investigated site than in the comparable reference site with less contaminated status. The community structure in mangrove soils at the current study site was, to a remarkable extent, different from those in the tropical mangrove wetlands around the world.

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Spatial distribution and temporal variation of microcrustaceans assembly (Cladocera and Copepoda) in different compartments of a reservoir in the brazilian semiarid region

Acta Limnologica Brasiliensia ◽

10.1590/s2179-975x9616 ◽

2018 ◽

Vol 30 (0) ◽

Cited By ~ 1

Author(s):

Josiane Souza Santos ◽

Nadson Ressyé Simões ◽

Sérgio Luiz Sonoda

Keyword(s):

Spatial Distribution ◽

Spatial Variation ◽

Temporal Variation ◽

Aquatic Macrophytes ◽

Temporal Dynamics ◽

Lateral Compartment ◽

Spatial And Temporal Variation ◽

Semiarid Region ◽

Brazilian Semiarid ◽

Significant Spatial Variation

Abstract Aim: The objective of this study was to investigate the spatial and temporal variation of microcrustacean assemblages of a reservoir in the Brazilian semiarid region. Methods Physical and chemical water variables and samples of microcrustaceans were collected at eight sites of the reservoir between July 2013 and November 2014, in a total of seven campaigns. For this study, the reservoir was categorized in two compartments: lateral and central. Results Limnological variables showed significant temporal variation (PERMANOVA, Pseudo-F = 19.51, p = 0.001). Higher turbidity values and suspended solids were observed in the rainiest months, while during the dry months, we measured higher values of transparency, dissolved oxygen, and chlorophyll-a. It was not found significant spatial variation of limnological variables (PERMANOVA, Pseudo-F = 0.96; p = 0.394). During the study period, ten species were recorded: four Cladocera (Ceriodaphnia cornuta, Daphnia gessneri, Diaphanosoma birgei and Diaphanosoma spinulosum ) three Copepoda Calanoida (Argyrodiaptomus azevedoi, Notodiaptomus cearensis and Notodiaptomus iheringi) and three Copepoda Cyclopoida (Macrocyclops albidus, Thermocyclops minutus and Thermocyclops decipiens). The microcrustacean assemblages showed significant temporal variation (PERMANOVA, Pseudo-F = 4.34; p = 0.001) as well as significant spatial variation (PERMANOVA, Pseudo-F = 9.46; p = 0.001). The highest values of abundance and richness were observed in the lateral compartment, this result is mainly related to the presence of aquatic macrophytes in this region, because the analysis of partial RDA indicated that limnological variables explained only 11% of this variation (Pseudo-F = 2.08, p = 0.001). Conclusions The results suggest that the seasonality of the semiarid is an important factor in the temporal dynamics of the limnological variables, while the aquatic macrophytes play an important role in the spatial distribution of the microcrustacean assembly.

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Spatial and temporal variation in littoral-zone benthic invertebrates from three south-central Ontario lakes

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f95-136 ◽

1995 ◽

Vol 52 (7) ◽

pp. 1406-1420 ◽

Cited By ~ 15

Author(s):

R. A. Reid ◽

K. M. Somers ◽

S. M. David

Keyword(s):

Temporal Variation ◽

Benthic Invertebrates ◽

Seasonal Changes ◽

Littoral Zone ◽

Spatial And Temporal Variation ◽

South Central ◽

Temporal Factors ◽

Follow Up Studies ◽

Spatial Differences

Surveys of benthic invertebrates have revealed patterns attributed to the impacts of acid deposition. Unfortunately, these patterns may be confounded by temporal variation that will affect follow-up studies of the recovery of these communities. Here, we assess spatial and temporal variation in time-limited, kick-and-sweep collections of littoral-zone benthos. Spatial variation comprised five sites representing the predominant nearshore substrates in each of three lakes. Temporal variation spanned a different scale in each lake with five sites sampled: (i) twice on the same day, (ii) once a week for 3 weeks, and (iii) four times through the ice-free season. Variation was quantified using a model II analysis of variance. Spatial differences predominated in same-day samples (60.4% of the variation on average) and those collected over a 3-week period (46.1%). In contrast, samples collected over the ice-free season revealed that spatial and temporal factors accounted for 9.4 and 25.6% of the variation. We conclude that our collections of littoral macrobenthos are highly repeatable if sampling is restricted to short periods (e.g., 3 weeks). Surveys spanning longer periods may incorporate considerable temporal variation from seasonal changes in abundance.

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Estimation of mean annual effective dose through radon concentration in the water and indoor air of Islamabad and Murree

Radiation Protection Dosimetry ◽

10.1093/rpd/ncq160 ◽

2010 ◽

Vol 141 (2) ◽

pp. 183-191 ◽

Cited By ~ 48

Author(s):

N. Ali ◽

E. U. Khan ◽

P. Akhter ◽

F. Khan ◽

A. Waheed

Keyword(s):

Effective Dose ◽

Indoor Air ◽

Radon Concentration ◽

Annual Effective Dose

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Radon concentration in drinking water in villages nearby Rafsanjan fault and evaluation the annual effective dose

Journal of Radioanalytical and Nuclear Chemistry ◽

10.1007/s10967-014-3345-1 ◽

2014 ◽

Vol 302 (3) ◽

pp. 1167-1176 ◽

Cited By ~ 8

Author(s):

Mohammad Malakootian ◽

Zahra Khashi ◽

Farnaz Iranmanesh ◽

Mojtaba Rahimi

Keyword(s):

Drinking Water ◽

Effective Dose ◽

Radon Concentration ◽

Annual Effective Dose

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Spatial variation in CO2 efflux from the soil in a mature beech forest ecosystem.

10.5194/egusphere-egu21-789 ◽

2021 ◽

Author(s):

Yihan Cai ◽

Takahiro Nishimura ◽

Hideyuki Ida ◽

Mitsuru Hirota

Keyword(s):

Spatial Variation ◽

Temporal Variation ◽

Forest Ecosystem ◽

Linear Regression Analysis ◽

Basal Area ◽

Beech Forest ◽

Controlling Factors ◽

Spatial And Temporal Variation ◽

Canopy Openness ◽

Co2 Efflux

&#160;Soil respiration (Rs) is the second largest carbon flux between the atmosphere and terrestrial ecosystem. Because of the large proportion, even small change in Rs would considerably impact the global carbon cycle. Therefore, it is important to accurately estimate Rs by taking its spatial and temporal variation into consideration. While the temporal variation of Rs and its controlling factors have been well-described, large unexplainable part still has been remained in the spatial variation of Rs especially in the forest ecosystems with complex structures. The objective of this study is to fill the knowledge gap about spatial variation of Rs and its controlling factors in a typical mature beech forest in Japan. Hypotheses of this study were, 1) Rs would show large spatial variation in the mature beech forest, 2) the spatial variation of Rs was mainly influenced by soil water content (SWC) and soil temperature (ST), 3) the two key factors were determined by the forest structures. This study was conducted in a 1- ha permanent study plot in the mature beech forest with significant gap-mosaic structures. To examine these hypotheses, Rs, SWC, ST and parameters related to forest structure, i.e. sum of basal area, diameter at breast height, number of trees, number of species within a radius of 5 m from the Rs measurement points, and canopy openness were measured at 121 points in different season between 2012 to 2013. In this study, all the measurements of Rs were conducted by using alkali-absorption technique.&#160;Coefficient of variation of Rs was between 25 - 28 % which was similar to that of SWC in all the measurements. The spatial variation of Rs was relatively higher in July, August and September than that in June and October. There was no significant relationship in the spatial variation between Rs and ST in all the measurements, meanwhile, Rs was well explained by SWC in measurements conducted in August, September and October. Multiple linear regression analysis indicated that canopy openness and sum of basal area showed significant positive and negative correlation with SWC, respectively. And canopy openness explained SWC much more than sum of basal area did. This result suggested that SWC, the key factor determined the spatial variation of Rs, cannot be only explained by stems distribution and their characteristics, but also canopy architecture in the forest ecosystem.

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