scholarly journals Tracing the Origin of Groundwater Nitrate in an Area Affected by Acid Rain Using Dual Isotopic Composition of Nitrate

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Tianming Huang ◽  
Zhenbin Li ◽  
Baoqiang Ma ◽  
Yin Long
Keyword(s):  
Isotopic Composition ◽  
Acid Rain ◽  
Nitrogen Cycle ◽  
Soil Nitrogen ◽  
Average Concentration ◽  
Mountainous Area ◽  
Rock Weathering ◽  
High Concentration ◽  
Groundwater System ◽  
Denitrification Process

Acid rain with a relatively high concentration of ammonium and nitrate can accelerate rock weathering. However, its impact on groundwater nitrate is uncertain. This study evaluated the dual isotopic composition of nitrate (δ15N-NO3- and δ18O-NO3-) from precipitation to groundwater in a rural mountainous area affected by acid rain. The average concentration for NH4+ is 1.25 mg/L and NO3- is 2.59 mg/L of acid rain. Groundwater NO3- concentrations ranged from <0.05 to 11.8 mg/L (baseline), and NH4+ concentrations ranged from 0.06 to 0.28 mg/L. The results show that groundwater δ18O-NO3- values (-4.7‰ to +4.2‰) were lower than the values of rainfall δ18O-NO3- (+24.9‰ to +67.3‰), suggesting that rainfall NO3- contributes little to groundwater NO3-. Groundwater δ15N-NO3- values (+0.1‰ to +7.5‰) were higher than the values of δ15N-NO3- derived from the nitrification of rainfall NH4+ (less than -4.7‰ in the study area), suggesting that nitrification of rainfall NH4+ also contributes little to groundwater NO3-. This implies that rainfall NO3- and NH4+ have been utilized. The dual isotopic composition of nitrate shows that baseline groundwater NO3- is derived mainly from nitrification of soil nitrogen. The denitrification process is limited in the groundwater system. This study shows that the rainfall NO3- and NH4+ contribute little to groundwater NO3-, improving the understanding of the nitrogen cycle in areas with a high concentration of NH4+ and NO3- in rainfall.

scholarly journals GLOBAL PRODUCTION CONCENTRATION OF MEDIUM DENSITY FIBERBOARD (MDF) (1995 - 2016)

2018 ◽  
Vol 42 (5) ◽  
Author(s):  
Thaisa de Sousa Selvatti ◽  
Luis Antônio Coimbra Borges ◽  
Helena Cristina Carvalho Soares ◽  
Álvaro Nogueira de Souza ◽  
Luiz Moreira Coelho Junior
Keyword(s):  
Gini Index ◽  
Concentration Ratio ◽  
Concentration Index ◽  
Medium Density Fiberboard ◽  
Average Concentration ◽  
Medium Density ◽  
High Concentration ◽  
The World ◽  
Concentration Degree ◽  
Production Concentration

ABSTRACT This papaer analyzed the global MDF production and its concentration degree between 1995 and 2016. In order to measure and analyze this concentration, we used the Concentration Ratio [CR(k)], the Herfindahl-Hirschman Index (HHI), Theil Entropy Index (E), Hall and Tideman Index (HTI), the Comprehensive Concentration Index (CCI), and the Gini Index (G). Global MDF production grew 12.81% p.a. from 1995 to 2016, reaching 99 million m3 at the end of the time series. China took over the hegemony in 2001 and arrived in 2016 with about 60% of the world’s MDF supply. The CR(k) of the global MDF production inferred a high concentration, mainly in the CR(4) from 2009. The CR(8) remained with a moderately high average concentration. During this period more than 90% of the offer was retained in the CR(20). The HHI, E and HTI indices corroborate that there is high concentration in global MDF production, as well as the CCI in the studied period. The inequality indicated by G also presented increasing behavior and was classified as strong and very strong. The concentration indicators were efficient in evaluating the concentration degree of the world MDF supply.

Groundwater and soil CO2 efflux weekly monitoring network for the surveillance of Cumbre Vieja volcano, Canary Islands

2020 ◽  
Author(s):  
Cecilia Amonte ◽  
Alana Mulliss ◽  
Elizabeth Sampson ◽  
Alba Martín-Lorenzo ◽  
Claudia Rodríguez-Pérez ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Monitoring Program ◽  
Monitoring Network ◽  
Volcano Monitoring ◽  
Co2 Efflux ◽  
Chemical Parameters ◽  
High Concentration ◽  
Average Value ◽  
Physical Chemical ◽  
Cumbre Vieja

&lt;p&gt;La Palma Island (708.32 km&lt;sup&gt;2&lt;/sup&gt;) is located at the north-western end of the Canary Archipelago and is one of the youngest of the archipelago. In the last 123 ka, volcanic activity has taken place exclusively at Cumbre Vieja, the most active basaltic volcano in the Canaries, which is located at the southern part of the island. Since no visible geothermal manifestations occur at the surface environment of this volcano, during the last 20 years there has been considerable interest in the study of diffuse degassing as a powerful tool in the volcano monitoring program. In this study we have used two different geochemical approaches for volcano monitoring from October 2017 to November 2019. First, we have developed a network of 21 closed static chambers to determine soil CO&lt;sub&gt;2&lt;/sub&gt; effluxes. Additionally, we have monitored physical-chemical parameters (temperature, pH, electrical conductivity -EC-) and chemical/isotopic composition and dissolved gases in the water of two galleries (Pe&amp;#241;a Horeb and Trasvase Oeste) and one water well (Las Salinas). Soil CO&lt;sub&gt;2&lt;/sub&gt; effluxes for the alkaline traps showed an average value of 7.4 g&amp;#183;m&lt;sup&gt;-2&lt;/sup&gt;&amp;#183;d&lt;sup&gt;-1&lt;/sup&gt; for the entire Cumbre Vieja volcano. The gas sampled on the head space of the traps can be considered as CO&lt;sub&gt;2&lt;/sub&gt;-enriched air, showing an average value of 1,942 ppmV of CO&lt;sub&gt;2&lt;/sub&gt;. Regarding the CO&lt;sub&gt;2&lt;/sub&gt; isotopic composition (&amp;#948;&lt;sup&gt;13&lt;/sup&gt;C-CO&lt;sub&gt;2&lt;/sub&gt;), most of the stations exhibited CO&lt;sub&gt;2&lt;/sub&gt; composed by different mixing degrees between atmospheric and biogenic CO&lt;sub&gt;2&lt;/sub&gt; with slight contributions of deep-seated CO&lt;sub&gt;2&lt;/sub&gt;, with an average value of -19.3&amp;#8240;. The results of the physical-chemical parameters measured in waters showed mean temperature values of 23.7&amp;#186;C, 19.6&amp;#186;C and 22.1&amp;#186;C, 7.40, 6.27 and 6.60 for the pH and 1,710 &amp;#181;S&amp;#183;cm&lt;sup&gt;-1&lt;/sup&gt;, 411 &amp;#181;S&amp;#183;cm&lt;sup&gt;-1&lt;/sup&gt; and 41,100 &amp;#181;S&amp;#183;cm&lt;sup&gt;-1&lt;/sup&gt; for the EC, for Pe&amp;#241;a Horeb, Trasvase Oeste and Las Salinas, respectively. The &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C-CO&lt;sub&gt;2&lt;/sub&gt; composition of the dissolved gas has a mean value of -7.8&amp;#8240;, -10.2&amp;#8240; and -3.8&amp;#8240; vs. VPDB for Pe&amp;#241;a Horeb, Trasvase Oeste and Salinas, respectively. The highest values of CO&lt;sub&gt;2&lt;/sub&gt; efflux coincided with the stations showing highest CO&lt;sub&gt;2&lt;/sub&gt; concentration values located at the southern end of Cumbre Vieja, where the most recent volcanic eruption took place, and also on the northwest flank. This is in accordance with the results obtained for Las Salinas well, located in the south of the island, which show a high concentration of dissolved CO&lt;sub&gt;2&lt;/sub&gt; and &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C-CO&lt;sub&gt;2&lt;/sub&gt; values with a strong deep-seated CO&lt;sub&gt;2&lt;/sub&gt; contribution. This study represents an interesting contribution to detect early warning signals of future unrest episodes at Cumbre Vieja.&lt;/p&gt;

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