scholarly journals Investigating the effect of lab bias on long-term stream chemistry data

2021 ◽  
Author(s):  
Cindi L. Brown ◽  
Chelcy F. MiEniat ◽  
Jennifer D. Knoepp
Keyword(s):  
Inorganic Nitrogen ◽  
Flow Analysis ◽  
Stream Chemistry ◽  
Concentration Data ◽  
Clear Cut ◽  
Chemistry Data ◽  
Data User ◽  
Data Points ◽  
Corrected Data

Abstract Long-term (LT) stream chemistry studies are used to examine changes in and responses to the environment. Much of the data collected over long periods of time goes through changes in instrumentation, methods, and personnel potentially resulting in changing values. A data user must understand these measures of data quality through quality control (QC) results to know with certainty if trends are real or attributable to other factors. We used the Web of Science database search engine to search for LT stream chemistry studies. For each study, we then determined: record or study length; if QC was reported; and if QC was used. We found that 33% of papers reported QC in the method, and 12% presented the QC in the results. Next, we conducted a case study on 46 years of stream chemistry data to evaluate the data with and without the application of QC protocols from two watersheds (WS) at Coweeta Hydrologic Laboratory; WS 7; clear-cut in 1967–77 and adjacent WS 2 which serves as a reference. We focused on nitrogen and sulfur due to their importance in understanding the forest ecosystem response to disturbance (NO3) and acid deposition (SO4). We determined average annual dissolved inorganic nitrogen (DIN) export (NH4 + NO3 = DIN) using three methods for censoring values below the method detection limit (mdl): (1) the found value, (2) the value of zero, and (3) one-half the mdl value. We found that DIN export for WS 2/WS 7 was (1) 66.9/831.4 (g ha−1 yr−1), (2) 45.4/808.0 (g ha−1 yr−1), and (3) 72.1/823.2 (g ha−1 yr−1) using the three censoring methods, and that the export estimate was significantly different for WS 2 but not for WS 7 (P = 0.001). We found that on average stream NH4 concentrations were below the mdl 58% of the time until an instrument change in 1994 resulted in improved mdls resulting in fewer data points below detection. We found increased bias for stream SO4 concentration following an instrumentation change from segmented flow analysis to ion chromatography. As a result, stream SO4 concentration data that were bias-corrected declined more rapidly in WS 2 compared with non-bias-corrected data, but not in WS 7. We conclude that including QC results with LT data is essential to verify data validity and give the data user a full understanding of the results.

scholarly journals Nutrient retention behind a tropical mega-dam: a case study of the Sardar Sarovar Dam, India

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Harish Gupta ◽  
S. Kiran Kumar Reddy ◽  
Mounika Chiluka ◽  
Vamshikrishna Gandla
Keyword(s):  
Arabian Sea ◽  
Inorganic Nitrogen ◽  
Nutrient Retention ◽  
Significant Loss ◽  
N Removal ◽  
Narmada River ◽  
Sardar Sarovar ◽  
The Impact

AbstractIn this study, we demonstrate the impact of the construction of a mega-dam on the nutrient export regime of a large tropical river into the Arabian Sea. Long-term (11 years) fortnight nutrient parameters, upstream and downstream to Sardar Sarovar (SS) Dam, were examined to determine the periodical change in nutrient fluxes from the Narmada River, India. During this 11-year period, the average discharge of the Narmada River upstream to Rajghat (35.3 km3 year−1) was higher than that of downstream at Garudeshwar (33.9 km3 year−1). However, during the same period, the suspended sediment load was reduced by 21 million tons (MT) from 37.9 MT at Rajghat to 16.7 MT at Garudeshwar. Similarly, mean concentrations of dissolved silica (DSi) reduced from 470 (upstream) to 214 µM (downstream), dissolved inorganic phosphate (DIP) from 0.84 to 0.38 µM, and dissolved inorganic nitrogen (DIN) from 43 to 1.5 µM. It means that about 54%, 55%, and 96% flux of DSi, DIP, and DIN retained behind the dam, respectively. The estimated denitrification rate (80,000 kg N km−2 year−1) for the reservoir is significantly higher than N removal by lentic systems, globally. We hypothesize that processes such as biological uptake and denitrification under anoxic conditions could be a key reason for the significant loss of nutrients, particularly of DIN. Finally, we anticipated that a decline in DIN fluxes (by 1.13 × 109 mol year−1) from the Narmada River to the Arabian Sea might reduce the atmospheric CO2 fixation by 7.46 × 109 mol year−1.

scholarly journals A Mixed-Methods Investigation into Barriers for Sharing Geospatial and Resilience Flood Data in the UK

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1235
Author(s):  
Luke Waterman ◽  
Mónica Rivas Casado ◽  
Emma Bergin ◽  
Gary McInally
Keyword(s):  
Data Sharing ◽  
Local Politics ◽  
Critical Role ◽  
Third Sector ◽  
Structured Interviews ◽  
Average Temperature ◽  
Third Sector Organisations ◽  
Data Points ◽  
The Uk

With increases in average temperature and rainfall predicted, more households are expected to be at risk of flooding in the UK by 2050. Data and technologies are increasingly playing a critical role across public-, private- and third-sector organisations. However, barriers and constraints exist across organisations and industries that limit the sharing of data. We examine the international context for data sharing and variations between data-rich and data-sparse countries. We find that local politics and organisational structures influence data sharing. We focus on the case study of the UK, and on geospatial and flood resilience data in particular. We use a series of semi-structured interviews to evaluate data sharing limitations, with particular reference to geospatial and flood resilience data. We identify barriers and constraints when sharing data between organisations. We find technological, security, privacy, cultural and commercial barriers across different use cases and data points. Finally, we provide three long-term recommendations to improve the overall accessibility to flood data and enhance outcomes for organisations and communities.

scholarly journals Integrating current and historical water chemistry data with long-term piezometric records to develop a regional-scale conceptual flow model: Las Salinas spring, Medina del Campo, Spain

2021 ◽  
Vol 34 ◽  
pp. 100781
Author(s):  
A. De la Hera-Portillo ◽  
J. López-Gutiérrez ◽  
C. Marín-Lechado ◽  
P. Martínez-Santos ◽  
A. Ruíz-Constán ◽  
...  
Keyword(s):  
Water Chemistry ◽  
Flow Model ◽  
Regional Scale ◽  
Chemistry Data

Third Revision of the Bottom-up Global Surface Seawater Dimethyl Sulphide Climatology (DMS-Rev3) 

2021 ◽  
Author(s):  
Shrivardhan Hulswar ◽  
George Manville ◽  
Rafel Simo ◽  
Marti Gali ◽  
Thomas G. Bell ◽  
...  
Keyword(s):  
Dimethyl Sulphide ◽  
Surface Seawater ◽  
High Concentration ◽  
Concentration Data ◽  
Bottom Up ◽  
High Productivity ◽  
Geographic Boundaries ◽  
Data Points ◽  
Biogeochemical Provinces ◽  
Global Surface

<p>An updated estimation of the bottom-up global surface seawater dimethyl sulphide (DMS) climatology, DMS-Rev3, is the third of its kind and includes five significant changes from the last climatology, ‘L11’ (Lana et al., 2011) that was released about a decade ago. The first change is the inclusion of new observations that have become available over the last decade, i.e., the total number of observations included in DMS- Rev3 are 865,109 as compared to 47,313 data points used in the last estimation (~1728% increase in raw data). The second was significant improvements in data handling, processing, filtering, to avoid bias due to different observation frequencies. Thirdly, we incorporated the dynamic seasonal changes observed in the ocean biogeochemical provinces and their variable geographic boundaries. Fourth change was refinements in the interpolation algorithm used to fill up the missing data. And finally, an upgraded smoothing algorithm based on observed DMS variability length scales (VLS) which helped reproduce a more realistic distribution of the DMS concentration data. The results show that DMS-Rev3 estimates the global annual mean DMS concentration at 2.34 nM, 4% lower than the current bottom-up ‘L11’ climatology. However, significant regional differences of more than 100% are observed. The largest changes are observed in high concentration regions such as the polar oceans, although oceanic regions which were under-sampled in the past also show large differences. DMS-Rev3 reduces the previously observed patchiness in high productivity regions.</p>

A Postassessment Test of 100,000 h Creep Rupture Strength of Grade 91 Steel at 600 °C

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
K. Maruyama ◽  
N. Sekido ◽  
K. Yoshimi
Keyword(s):  
Rupture Strength ◽  
Creep Rupture ◽  
Creep Rupture Strength ◽  
Data Points ◽  
Predicted Values ◽  
Grade 91 ◽  
Term Creep ◽  
Term Data ◽  
Grade 91 Steel

Predictions as to 105 h creep rupture strength of grade 91 steel have been made recently. The predicted values are examined with long-term creep rupture data of the steel. Three creep rupture databases were used in the predictions: data of tube products of grade 91 steel reported in National Institute for Materials Science (NIMS) Creep Data Sheet (NIMS T91 database), data of T91 steel collected in Japan, and data of grade 91 steel collected by an American Society of Mechanical Engineers (ASME) code committee. Short-term creep rupture data points were discarded by the following criteria for minimizing overestimation of the strength: selecting long-term data points with low activation energy (multiregion analysis), selecting data points crept at stresses lower than a half of proof stress (σ0.2/2 criterion), and selecting data points longer than 1000 h (cutoff time of 1000 h). In the case of NIMS T91 database, a time–temperature parameter (TTP) analysis of a dataset selected by multiregion analysis can properly describe the long-term data points and gives the creep rupture strength of 68 MPa at 600 °C. However, TTP analyses of datasets selected by σ0.2/2 criterion and cutoff time of 1000 h from the same database overestimate the data points and predict the strength over 80 MPa. Datasets selected by the same criterion from the three databases provide similar values of the strength. The different criteria for data selection have more substantial effects on predicted values of the strength of the steel than difference of the databases.

scholarly journals TO THE QUESTION OF COMPREHENSIVE ASSESSMENT OF SURFACE WATER IN THE CENTRAL CAUCASUS DURING WINTER BETWEEN AND SUMMER FLOOD

2021 ◽  
Vol 6 (5(55)) ◽  
pp. 22-27
Author(s):  
Liliya Zuberovna Zhinzhakova ◽  
Elena Alexandrovna Cherednik
Keyword(s):  
Water Quality ◽  
Surface Waters ◽  
Inorganic Nitrogen ◽  
High Water ◽  
Polluted Water ◽  
Trace Impurities ◽  
Central Caucasus ◽  
Summer Flood

Based on long-term observations, the assessment of the pollution of the rivers of the Central Caucasus was carried out by comparing the calculated coefficients of the complexity of pollution and the specific combinatorial index of pollution of surface waters, and the quality classes were determined. The results of chemical analysis of the concentration levels of trace impurities (Mo, Pb, Zn, V, Ni, Cr, Mn, Ag) and inorganic nitrogen compounds (NO2 -, NO3 — and NH4 +) in the waters of 13 rivers in two permanent sections of each watercourse were used. The results of calculating the indicators of pollution in the waters of rivers of winter low water and summer high water are presented. The most polluted watercourses and the frequency of pollution in each river are identified, estimated by the values of the specific combinatorial index of water pollution, the coefficient of complexity of pollution, and the class of water quality is presented. The assessment of the most polluted water bodies during the winter low-water period and summer flood is given according to the classification of water quality. According to long-term observations, the features of watercourses and their differences in terms of pollution are presented.

scholarly journals Annual nitrate load patterns in an agricultural watershed in consecutive dry years

2021 ◽  
Author(s):  
Shuai Chen ◽  
Xiaohong Ruan
Keyword(s):  
Nitrogen Loss ◽  
Agricultural Watershed ◽  
Agricultural Watersheds ◽  
Concentration Data ◽  
Data Set ◽  
Total Load ◽  
Huai River ◽  
Separate Point ◽  
Load Characteristics

Abstract Nitrate (NO3-N) load characteristics in consecutive dry years in the Huai River Basin (HRB), China, were examined using streamflow and NO3-N concentration data. The data set spanned 12 years including three consecutive dry years. Baseflow separation, load estimation, and nonparametric linear regression were applied to separate point source (PS), baseflow, and surface runoff NO3-N loads from the total load. The mean annual nonpoint source (NPS) load was 2.84 kg·ha−1·yr−1, accounting for 90.8% of the total load. Baseflow contributed approximately one-fourth of the natural runoff and half of the NPS load. The baseflow nitrate index (i.e., the ratio of baseflow NO3-N load to total NPS NO3-N load) was 25.4% higher in consecutive dry years than in individual dry years. This study demonstrated that baseflow is the preferential hydrological pathway for NO3-N transport in the HRB and that baseflow delivers a higher NO3-N percentage to streams under long-term drought than under short-term drought. This study highlights the alarming evidence that continuous drought caused by climate change may lead to a higher rate of nitrogen loss in agricultural watersheds.

scholarly journals Monitoring long-term changes of glacial seismic activity with continuous seismological observations: a case study from Spitsbergen

2016 ◽  
Author(s):  
W. Gajek ◽  
J. Trojanowski ◽  
M. Malinowski
Keyword(s):  
Seismic Activity ◽  
Seismic Station ◽  
Flow Analysis ◽  
Seismic Signal ◽  
Signal Frequency ◽  
Steady Increase ◽  
Fuzzy Logic Algorithm ◽  
Temperature And Precipitation ◽  
Seismological Data

Abstract. Changes in the global temperature balance have proved to have a major impact on the cryosphere and therefore retreating glaciers are the symbol of the warming climate. Long-term measurements of geophysical parameters provide the insight into the dynamics of those processes over many years. Here we explore the possibility of using data recorded by permanent seismological stations to monitor glacial seismic activity. Our study focuses on year-to-year changes in seismicity of the Hansbreen glacier (southern Spitsbergen). We have processed 7-year-long continuous seismological data recorded by a broadband station located in the fjord of Hornsund, obtaining seismicity distribution between 2008 and 2014. To distinguish between glacier- and non-glacier-origin events with the data from only one seismic station in the area, we developed a new fuzzy logic algorithm based on the seismic signal frequency and the energy flow analysis. Our research has revealed that the number of detected glacier-origin events over the last two years has doubled. We also observed that the annual events distribution correlates well with the temperature and precipitation data. In order to further support our observations, we have analysed 5-year-long seismological data recorded by a broadband station located in Ny-Ålesund (western Spitsbergen). Distribution of glacier-origin tremors detected in the vicinity of the Kronebreen glacier shows a steady increase from year to year, however not as significant as for the Hornsund dataset.

scholarly journals Thunderstorms and thunderstorm precipitations in southern Poland

2014 ◽  
Vol 2 (3) ◽  
pp. 33-46
Author(s):  
Zuzanna Bielec-Bąkowska
Keyword(s):  
Temporal Variability ◽  
Daily Precipitation ◽  
Overwhelming Majority ◽  
Spatial And Temporal Variability ◽  
Southern Poland ◽  
Clear Cut ◽  
Term Change ◽  
Atmospheric Fronts ◽  
Precipitation Events

AbstractThis paper addresses spatial and temporal variability in the occurrence of thunderstorms and related precipitation in southern Poland between 1951 and 2010. The analysis was based on thunderstorm observations and daily precipitation totals (broken down into the few ranges) from 15 meteorological stations. It was found that precipitation accompanied an overwhelming majority of thunderstorms. The most frequent range of thunderstorm precipitation totals was 0.1–10.0 mm which accounted for 60% of all values while precipitation higher than 20.0 mm accounted only for ca. 8%. During the study period, long-term change in the number of days with thunderstorm precipitation within a certain range displayed no clear-cut trends. Exceptions included: 1) an increase in the number of days with thunderstorm precipitation in the lowest range of totals (0.1–10.0 mm) at Katowice, Tarnów, Rzeszów and Lesko and decrease at Mt. Kasprowy Wierch, 2) an increase in the range 10.1–20.0 mm at Zakopane and 20.1–30.0 mm at Opole, 3) a decrease of the top range (more than 30.0 mm) at Mt. Śnieżka. It was found that the heaviest thunderstorm precipitation events, i.e. totalling more than 30 mm, and those events that covered all or most of the study area, occurred at the time of air advection from the southern or eastern sectors and a passage of atmospheric fronts.

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