scholarly journals Impact of different fertilizers on carbonate weathering in a typical karst area, Southwest China: a field column experiment

2017 ◽  
Vol 5 (3) ◽  
pp. 605-616 ◽  
Author(s):  
Chao Song ◽  
Changli Liu ◽  
Guilin Han ◽  
Congqiang Liu

Abstract. Carbonate weathering, as a significant vector for the movement of carbon both between and within ecosystems, is strongly influenced by agricultural fertilization, since the addition of fertilizers tends to change the chemical characteristics of soil such as the pH. Different fertilizers may exert a different impact on carbonate weathering, but these discrepancies are as yet not well-known. In this study, a field column experiment was conducted to explore the response of carbonate weathering to the addition of different fertilizers. We compared 11 different treatments, including a control treatment, using three replicates per treatment. Carbonate weathering was assessed by measuring the weight loss of limestone and dolostone tablets buried at the bottom of soil-filled columns. The results show that the addition of urea, NH4NO3, NH4HCO3, NH4Cl and (NH4)2CO3 distinctly increased carbonate weathering, which was attributed to the nitrification of NH4+. The addition of Ca3(PO4)2, Ca–Mg–P and K2CO3 induced carbonate precipitation due to the common ion effect. The addition of (NH4)3PO4 and NaNO3 had a relatively small impact on carbonate weathering in comparison to those five NH4-based fertilizers above. The results of NaNO3 treatment raise a new question: the negligible impact of nitrate on carbonate weathering may result in an overestimation of the impact of N fertilizer on CO2 consumption by carbonate weathering on the regional/global scale if the effects of NO3 and NH4 are not distinguished.

2016 ◽  
Author(s):  
Chao Song ◽  
Changli Liu ◽  
Guilin Han

Abstract. Carbonate weathering, as a significant vector for the movement of carbon both between and within ecosystems, are strongly influenced by anthropogenic perturbations such as agricultural fertilization. Different fertilizer may exert a different impact on carbonate weathering, but their differences are not still well-known so far. In this study, a field column experiment was employed to explore the responses of carbonate weathering to different fertilizer addition. The eleven different treatments with three replicates including control, NH4NO3, NH4HCO3, NaNO3, NH4Cl, (NH4)2CO3, Ca3(PO4)2, (NH4)3PO4, fused calcium-magnesium phosphate fertilizer (Ca-Mg-P), Urea and K2CO3 were established in this column experiment, where limestone and dolostone tablets were buried at the bottom of each to determine the weathering amount and ratio of carbonate in soil. The result showed that the addition of urea, NH4NO3, NH4HCO3, NH4Cl and (NH4)2CO3 distinctly increased carbonate weathering, which was attributed to the nitrification of NH4+, and the addition of Ca3(PO4)2, Ca-Mg-P and K2CO3 induced carbonate precipitation due to common ion effect. Whereas the (NH4)3PO4 and NaNO3 addition did not impact significantly on carbonate weathering. The results of NaNO3 treatment seem to be raising a new question: the little impact of nitrate on carbonate weathering may result in the overestimation of impact of N-fertilizer on CO2 consumption by carbonate weathering at the regional/global scale if the effect of NO3 and NH4 are not distinguished. Moreover, in order to avoid misunderstanding more or less, the statement that nitrogenous fertilizer can aid carbonate weathering should be replaced by ammonium fertilizer.


2021 ◽  
Author(s):  
Lianbin Cai ◽  
Xi Chen ◽  
Zhicai Zhang

<p>In carbonate rock regions, the bedrock compositions strongly influence regolith properties that, in turn, might play the primary role in plant growth and hydrological processes. Since bedrock experiences uneven weathering processes due to different regolith materials in a karst area, how hydrological functions of bedrock layer and overlying vegetation rely on the bedrock weathering degree is seldom investigated. The objectives of this study are to quantify the impacts of climate change and reforestation on runoff in a watershed with two main bedrocks (dissolvable carbonate rock in karst area and detrital rock in non-karst area) in southwest China. The analyses are firstly executed by decomposion of the hydro-meteorological series into two series (T1, 1992-2003 and T2, 2004-2015), which have different hydro-meteorological responses due to reforestation. This study investigates the impacts of climate change and reforestation on runoff using two approaches: the sensitivity-based approach (Budyko hypothesis) is applied to estimate the overall watershed change in runoff attributed to human activities and climate change, and a distributed hydrological model based on simple soil water balance routing is used to estimate change in runoff and hydrographs in the two main bedrock areas. The results show that the hydrological modelling overestimates climate induced decrease of streamflow (88.6%), compared to estimated result by the Budyko formula (76.6%). The decrease of mean precipitation from T1 to T2 in the non-carbonate area is very close to the carbonate area, the proportion of the climate change induced decrease of streamflow in the non-carbonate area (86.3%) is less than the carbonate area (90.5%), indicating that the drier climate tendency takes a greater effect on decrease of streamflow in the carbonate area than the non-carbonate area. By contrast, there is a greater alteration of land cover/use in the non-carbonate area than the carbonate area. These findings will help develop a better understanding of the impact of climate change and reforestation on runoff in southwest China.</p>


2019 ◽  
pp. 33-41
Author(s):  
V. L. Harutyunyan ◽  
S. V. Dokholyan ◽  
A. R. Makaryan

The presented study discusses the issues of applying the Common Customs Tariff (CCT) rates of the Eurasian Economic Union (EAEU) on rough diamonds and the impact thereof on the exports of stones cut and polished inArmeniaand then exported toRussia.Aim. The study aims to identify the possible strategies Armenian diamond cutting and polishing companies could adopt as a response to the application of the CCT rates on rough diamonds and how it would affect exports to various destinations, namely to Russia.Tasks. The authors analyze the current state of the gems and jewelry sector and substantiate the need to either integrate it into the jewelry manufacturing sector or to apply various strategies to facilitate exports to either Russia or other destinations in the medium term in response to the application of the CCT rates.Methods. This study uses general scientific methods of cognition, including analytical and methodological approaches and elements of forecasting. Possible strategies the Armenian diamond cutting and polishing companies could adopt in the medium term in response to the application of the EAEU CCT rates are determined using the analytical research method, forecasts in the context of the developments in the Armenian gem processing and jewelry market and global trends, statistical data on the imports and exports of cut and polished gems and jewelry for 2014–2018 published by the UN Comtrade Statistics.Results. Statistics on the exports of processed diamonds from 2014 to 2018 highlights the issue associated with the loss of competitiveness suffered by Armenian companies (mainly in comparison with Indian diamond cutters). The major global trends in the diamond cutting and polishing business indicate that it could be virtually impossible for Armenian cutters and polishers to compete with Indian companies in the medium term if they do not comes to investing in new technology to achieve operational efficiency. For these companies, it is important not to lose the Russian market due to an increase in the tariff rate and concentrate on the processing of gems that are larger than 1 carat. Another strategy to avoid an increase in the customs tariff rates would depend on the Armenian government’s ability to negotiate with Russia in respect of direct imports of diamond stones from Russian manufactures. Two other options for Armenian cutters involve focusing on cutting and polishing of rubies, sapphires, emeralds, etc. or integrating into the jewelry sector either by being the primary supplier or by considering this business as a channel to sell processed diamond stones by setting up their own jewelry manufacturing companies.Conclusions. With CCT going into effect in January 2021 and India’s dominant role in the diamond cutting and polishing business, Armenia needs to carefully consider all of the strategies the Armenian companies could adopt, as discussed above. As a member state of the EAEU, Armenia freely exports to Russia, however, further exports to Russia would depend on Armenia’s ability to ensure that cost-effective operations are in place, or to concentrate on the processing of precious gems rather than diamonds, or to switch to the manufacturing of jewelry items as a major export item.Practical Implication. The findings of this study could be of interest to the Ministry of Economy of the Republic of Armenia and Business Armenia that could be used in elaborating the strategy for the development of Armenian gems and jewelry sector of the economy.


2020 ◽  
Vol 26 (4) ◽  
pp. 358-365
Author(s):  
V. L. Harutyunyan ◽  
S. V. Dokholyan ◽  
A. R. Makaryan

1985 ◽  
Vol 17 (6-7) ◽  
pp. 1187-1198 ◽  
Author(s):  
G. Mance ◽  
A. R. O'Donnell

This paper discusses the derivation of environmental quality standards for coastal waters and the difficulties of using such standards for controlling industrial discharges. Attention is focused on the common List II substances, copper, chromium, lead, nickel, zinc and arsenic - and their effects on marine life. The adequacy of existing toxicity data is discussed and it is concluded that long exposure tests are required to provide information on sublethal effects. Such data are currently limited. It is also important that consideration be given to the effects that reducing salinities and increasing temperatures have in increasing the toxicity of these substances. The complexity of interpreting the results of laboratory toxicity data to coastal waters is discussed with reference to a study of the impact of an industrial discharge.


2020 ◽  
Vol 12 (17) ◽  
pp. 17374-17379
Author(s):  
W.G.D. Chathuranga ◽  
K. Kariyawasam ◽  
Anslem De Silva ◽  
W.A.Priyanka P. De Silva

We investigated the impact of dipteran predators on eggs in foam nests of the Common Hour-glass Tree Frog Polypedates cruciger Blyth, 1852 (Anura: Rhacophoridae) in central Sri Lanka.  Foam nests (n=24) of P. cruciger were examined at their natural breeding habitats and infected (n=8) and uninfected spawns (n=16) were identified.  Emerging tadpoles were collected in a water container hung under each spawn and the average number of tadpoles (N) hatched from infected spawns (N=0) was compared with that of uninfected spawns (N=354 ± 67).  Three severely infected spawns were brought to the laboratory and the fly larvae were reared until they metamorphosed to adults.  Morphological and molecular identification of the flies confirmed them as belonging to Caiusa testacea Senior-White, 1923 of the family Calliphoridae.  The infected spawns were completely destroyed and an estimated average of 400 P. cruciger eggs per spawn were lost.  The results revealed a high impact of Caiusa testacea on egg and embryo mortality of P. cruciger.


Author(s):  
Thomas A Lewis

Abstract As a discipline, the academic study of religion is strikingly fragmented, with little engagement or shared criteria of excellence across subfields. Although important recent developments have expanded the traditions and peoples studied as well as the methods used, the current extent of fragmentation limits the impact of this diversification and pluralization. At a moment when the global pandemic is catalyzing profound pressures on our universities and disciplines, this fragmentation makes it difficult to articulate to the public, to non-religious studies colleagues, and to students why the study of religion matters. We therefore too often fall back on platitudes. I argue for a revitalized methods and theories conversation that connects us even as it bears our arguments and disagreements about what we do and how. Courses in methods and theories in the study of religion represent the most viable basis we have for bringing the academic study of religion into the common conversation or argument that constitutes a discipline without sacrificing our pluralism.


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