Prof. Chhatra Sharma, PhD - Central Department of Environmental Science, Tribhuvan University - Professor

Prof. Chhatra Sharma

PhD

Central Department of Environmental Science, Tribhuvan University

Professor

Kathmandu, Bagmati | Nepal

Main Specialties: Other

Additional Specialties: Environmental Science

ORCID logohttps://orcid.org/0000-0003-0714-7411


Top Author

Prof. Chhatra Sharma, PhD - Central Department of Environmental Science, Tribhuvan University - Professor

Prof. Chhatra Sharma

PhD

Introduction

Chhatra Mani Sharma is a Professor of Academic Excellence at the Central Department of Environmental Science, Tribhuvan University, Nepal. He holds Gold Medal in MSc (Zoology) from the Central Department of Zoology, Tribhuvan University, Nepal. An MSc in Management of Natural Resources and Sustainable Agriculture was completed in 2003 from the Agricultural University of Norway, Norway. He obtained PhD in Nature Conservation and Management with a focus on fish ecology, biomanipulation, and pollutants (Mercury and Persistent Organic Pollutants) from the Norwegian University of Life Sciences, Norway. He was among TOP-20 Researchers at the Norwegian University of Life Sciences in 2008. He was awarded ‘Young International Scientist’ by the Chinese Academy of sciences in 2009 and worked at Institute of Tibetan Plateau Research for two years. He involved as Post-doc Researcher at the Laboratory of Green Chemistry, Lappeenranta University of Technology, Finland for 18 months (2013-14). He worked as a Visiting Scientist at the State Key Laboratory of Cryospheric Science of the Chinese Academy of Sciences as a PIFI Fellow. He has published more than 50 peer-reviewed journal articles until 2019. He has research experiences from Norway, Nepal and China.

Primary Affiliation: Central Department of Environmental Science, Tribhuvan University - Kathmandu, Bagmati , Nepal

Specialties:

Additional Specialties:

Research Interests:


View Prof. Chhatra Sharma’s Resume / CV

Education

Jan 2004 - Jan 2008
Norwegian University of Life Sciences
PhD
Ecology and Natural Resource Management
Aug 2001 - Jun 2003
Agricultural University of Norway
MS
NORAGRIC

Experience

Jul 2018 - Jul 2018
Tribhuvan University
Professor
Central Department of Environmental Science
Sep 2017 - Sep 2017
Chinese Academy of Sciences
Visiting Scientist
Northwest Institute of Eco-Environment and Resources
Apr 2013 - Sep 2014
Lappeenranta University of Technology
Post-doc Researcher
Green Chemistry
Mar 2010 - Jul 2012
Chinese Academy of Sciences
Young International Scientist
Institute of Tibetan Plateau Research
Jul 2008 - Jun 2008
Kathmandu University
Assistant Professor
Environmental Science and Engineering

Publications

39Publications

141Reads

34Profile Views

393PubMed Central Citations

Decoupling natural and anthropogenic mercury and lead transport from South Asia to the Himalayas

10.1021/acs.est.0c00429

Environmental Science & Technology

AbstractMercury (Hg) and lead (Pb) accumulation since the Industrial Revolution has been generally observed to increase concurrently in lake sedimentary records around the world. Located downwind during the monsoon season from the rapidly developing South Asia, the Himalayas and the Tibetan Plateau are expected to receive direct anthropogenic Hg and Pb loadings, yet the source, pathway, and effects of such transport remain poorly known due to logistic challenges in accessing this region. When studying the sediment record from Lake Gokyo (4750 m above sea level (a.s.l.)) in the Himalayas, we find remarkably different Hg and Pb accumulation trends over the past 260 years. Although Hg accumulation has continued to increase since the Industrial Revolution, Pb accumulation peaked during that time and has been decreasing since then. Stable isotope analysis reveals that the decoupling trends between these two elements are due to different sources and pathways of Hg and Pb in the region. Both δ202Hg and Δ199Hg have been increasing since the Industrial Revolution, suggesting that anthropogenic Hg emissions from South Asia have been continuously increasing and that the Indian monsoon-driven wet deposition of atmospheric Hg is the dominant pathway for Hg accumulation in the sediments. In contrast, analysis of 206Pb/207Pb and 208Pb/207Pb ratios suggests that Pb accumulation in the sediments originates primarily from natural sources and that the decreasing trend of Pb accumulation is most likely due to a weakening input of atmospheric mineral dust by the westerlies. These decoupling trends highlight the ongoing issue of transboundary Hg transport to the Himalayas and the Tibetan Plateau that are source waters for major freshwater systems in Asia and calls for regional and international collaborations on Hg emission controls in South Asia.

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April 2020

Impact Factor 7.149

1 Read

Measurement of mercury, other trace elements and major ions in wet deposition at Jomsom: The semi-arid mountain valley of the Central Himalaya

Volume 234, April 2020, 104691

Atmospheric Research

Abstract

South Asian pollutants can be transported and deposited via wet/dry deposition to the remote areas of the Himalayas and could pose a serious threat to the mountain ecosystems. Therefore, in order to understand the concentrations, fluxes, seasonal variation and origin of the mercury (Hg), major ions and trace elements, precipitation samples were collected during 2012–2013 from a data gap region, Jomsom, the high elevation semi-arid mountain valley in the central Himalayas. The volume-weighted mean (VWM) concentrations of ions followed the order of Ca2+ > Mg2+ > Na+ > NH4+ > SO42− > Cl > NO3 > K+. The concentration of Cd was lowest (0.07 μg L−1) whereas that of Fe was the highest (1073.59 μg L−1) in the precipitation samples. Wet deposition level of all the measured inorganic species was comparable to urban Lhasa but higher than those in remote alpine sites of the Tibetan Plateau (TP). This study shows that Hg and other inorganic constituents were higher in the non-monsoon season compared to monsoon due to enhanced washout of aerosols. Enrichment factor (EF), sea salt fraction, crustal and anthropogenic fractions, principal component analysis (PCA) and correlation coefficient analysis suggested that crustal dust and anthropogenic activities as the major sources of measured chemical species whereas the influence of sea-salt was minimal. In addition, local anthropogenic emissions were low suggesting that the majority of the pollutants could have been transported from the South Asian region to the high elevation mountains. Meanwhile, low precipitation and dry environment could have enhanced the concentrations of inorganic species in the arid region than other sites over the central Himalayas. This work adds new dataset of inorganic pollutants in wet precipitation and provides baseline information for an arid region environmental protection. However, there is a need for further long-term monitoring to understand the precipitation chemistry of the arid regions.

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April 2020

Impact Factor 4.114

Major ions and irrigation water quality assessment of the Nepalese Himalayan rivers

https://doi.org/10.1007/s10668-020-00694-1

Environment, Development and Sustainability

AbstractWater quality analysis of the Himalayan rivers for irrigation was carried out in 2013 that include the Dudh Koshi, Indrawati, Gandaki and Bagmati rivers from Nepal. Former three rivers originate at high altitudes and are glacier-fed rivers, whereas the Bagmati River originates at the high hill and flows through the capital city of Nepal. The river water samples were collected at 93 sites representing river from lowlands, mid-hills and high mountains of the Himalayas. Nine major ions (Na+, K+, Mg2+, Ca2+, F−, Cl−, SO2−4SO42−, HCO−3HCO3− and NO−3NO3−), pH, EC and TDS were analyzed so as to assess the water quality for irrigation. Irrigation water quality was assessed by calculating sodium adsorption ration (SAR), soluble sodium percentage (SSP or %Na) and water quality index (WQI). Although SAR indicated that all the water samples were having low values and could be suitable for the irrigation purpose, some sites from the Bagmati River were having high class of EC, rendering it not good for irrigation. Similar results were indicated by %Na as well as WQI results where low water qualities were observed from some highly contaminated sites in the city area. This clearly indicates the impacts of urbanization (anthropogenic) in river water quality for the irrigation in the Himalayan rivers of Nepal.

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March 2020

Impact Factor 1.676

11 Reads

Microbial mercury methylation in the cryosphere: Progress and prospects

https://doi.org/10.1016/j.scitotenv.2019.134150

Science of The Total Environment

Abstract

Mercury (Hg) is one of the most toxic heavy metals, and its cycle is mainly controlled by oxidation–reduction reactions carried out by photochemical or microbial process under suitable conditions. The deposition and accumulation of methylmercury (MeHg) in various ecosystems, including the cryospheric components such as snow, meltwater, glaciers, and ice sheet, and subsequently in the food chain pose serious health concerns for living beings. Unlike the abundance of knowledge about the processes of MeHg production over land and oceans, little is known about the sources and production/degradation rate of MeHg in cryosphere systems. In addition, processes controlling the concentration of Hg and MeHg in the cryosphere remains poorly understood, and filling this scientific gap has been challenging. Therefore, it is essential to study and review the deposition and accumulation by biological, physical, and chemical mechanisms involved in Hg methylation in the cryosphere. This review attempts to address knowledge gaps in understanding processes, especially biotic and abiotic, applicable for Hg methylation in the cryosphere. First, we focus on the variability in Hg concentration and mechanisms of Hg methylation, including physical, chemical, microbial, and biological processes, and transportation in the cryosphere. Then, we elaborate on the mechanism of redox reactions and biotic and abiotic factors controlling Hg methylation and biogeochemistry of Hg in the cryosphere. We also present possible mechanisms of Hg methylation with an emphasis on microbial transformation and molecular function to understand variability in Hg concentration in the cryosphere. Recent advancements in the genetic and physicochemical mechanisms of Hg methylation are also presented. Finally, we summarize and propose a method to study the unsolved issues of Hg methylation in the cryosphere.

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August 2019

Impact Factor 5.589

2 Reads

Concentration, spatiotemporal distribution, and sources of mercury in Mt. Yulong, a remote site in southeastern Tibetan Plateau.

Environ Sci Pollut Res Int 2019 Jun 13;26(16):16457-16469. Epub 2019 Apr 13.

State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Donggang West Rd. 320, Lanzhou, 730000, China.

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http://dx.doi.org/10.1007/s11356-019-05005-4DOI Listing
June 2019
1 Read
2.828 Impact Factor

Historical Black Carbon Reconstruction from the Lake Sediments of the Himalayan-Tibetan Plateau.

Environ Sci Technol 2019 05 29;53(10):5641-5651. Epub 2019 Apr 29.

State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources , Chinese Academy of Sciences , Lanzhou 730000 , China.

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http://dx.doi.org/10.1021/acs.est.8b07025DOI Listing
May 2019
7 Reads
5.330 Impact Factor

Spatial and temporal distribution of total mercury in atmospheric wet precipitation at four sites from the Nepal-Himalayas.

Sci Total Environ 2019 Mar 23;655:1207-1217. Epub 2018 Nov 23.

Central Department of Hydrology and Meteorology, Tribhuvan University, Kathmandu, Nepal.

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http://dx.doi.org/10.1016/j.scitotenv.2018.11.338DOI Listing
March 2019
3 Reads
4.099 Impact Factor

The genus Gomphonema (Bacillariophyta) in Rara Lake, Nepal: taxonomy, morphology, habitat distribution and description of five new species, and a new record for Gomphoneis qii

https://doi.org/10.1080/0269249X.2018.1528182

Diatom Research

During the first study of the diverse diatom assemblages in Rara Lake, the largest lake in Nepal, 11 species of Gomphonema, belonging to six morphological groups, and Gomphoneis qii could be investigated using light and scanning electron microscopy. Five new Gomphonema species are described: Gomphonema subodhiiGomphonema parasundaenseGomphonema raraenseGomphonema parapygmaeum and Gomphonema himalayaense. Known species included Gomphonema sublaticollumGomphonema cf. capitatumGomphonema minusculumGomphonema lateripunctatumGomphonema tergestinum (the only one previously recorded from Nepal) and Gomphonema vibrio. The history of the latter name is explained in detail. The distribution of the Gomphonema species, number of species and records in the littoral of the lake shore varied and was related to the presence of suitable substrata, land use and season, with more records and species present in spring than in autumn.

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December 2018

6 Citations

Impact Factor 1.169

Concentration and risk assessments of mercury along the elevation gradient in soils of Langtang Himalayas, Nepal

Human and Ecological Risk Assessment: An International Journal

The fragile Himalayan region could be regarded as the sink for various pollutants transported from urbanized and polluted areas of South Asia. Therefore, in order to understand the concentrations, spatial distribution, pollution, and risk assessments of toxic heavy metal, mercury (Hg), surface soil samples were taken from the central Himalayas in the Langtang region. The average THg concentration in the Langtang Himalayas was 35.75 ± 24.41(ngg−1), which is comparable to the Tibetan top soil values and slightly lower than world average soil values. In addition, an inverse relationship of THg with elevation were observed (i.e. decrease in concentration with increase in elevation) in the Langtang Himalayan soils. Meanwhile, THg concentrations and TOC% were significantly positively correlated at both the depths (0–10 and 10–20 cm), inferring the sorption capacity of organic carbon for Hg. The results of the geo-accumulation index (Igeo), enrichment factor (EF), and pollution index (PI) indicated limited or no pollution by Hg in the Himalayan soils. Further, surface soils had a low potential ecological risk in the region. Therefore, the Hg value from this study could be used for the further evaluation and calculation of Igeo, EF, and PI for water, soil, and aerosol in the Himalayan region as background reference value. However, Hg pollution from long-range transport and atmospheric deposition (wet/dry) in future could not be ignored in the Himalayan region.

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May 2018

4 Citations

Impact Factor 2.012

Hydrochemistry of Lake Rara: A high mountain lake in western Nepal

https://doi.org/10.1111/lre.12218

Lakes & Reservoirs: Research & Management

Abstract

High altitude ecosystems have important natural ecological functions but are under increasing impacts from human activities and climate change. A detailed analysis of the water chemistry of Lake Rara, a high mountain lake in western Nepal, was carried out in October 2015 and April 2016. A total of 31 water samples were collected. Major ions (Ca2+, Mg2+, Na+, K+, SO42−, NO3 and Cl) were analysed by ion chromatography. Si and PO43− were analysed following the standard protocols. Conductivity, pH, total dissolved solids (TDS), turbidity and dissolved oxygen (DO) were measured on‐site. The lake is oligotrophic characterized by low PO43− concentration (0.06 ± 0.01 mg/L), high DO values (6.73 ± 0.06 and 10.89 ± 0.86 mg/L), alkaline pH (8.42 ± 0.3 and 8.32 ± 0.23) and low conductivity (189.93 ± 5.3 and 189.22 ± 5.8 μS/cm). The concentrations of the major cations were in the order of Ca2+ > Mg2+ > K+ > Na+ (during both seasons), and for anions, it was HCO3 > SO42− > Cl > NO3 and HCO3 > Cl > NO3 > SO42− during postmonsoon and premonsoon, respectively. One‐way ANOVA revealed significant seasonal variations (p < 0.05) in most of the physicochemical parameters. The increased concentrations of most of the ions in the premonsoon time probably reflect long‐range transport of materials through dry deposition, whereas higher concentrations of NO3 and Cl in some sites possibly reflect the localized impacts of settlement and grazing. The lake water was classified as Ca(Mg)HCO3. High (Ca2+ + Mg2+)/Tz+ ratio (0.97 in postmonsoon and 0.95 in premonsoon) and low (Na+ + K+)/Tz+ ratio (0.03 in postmonsoon and 0.04 in premonsoon) confirm carbonate weathering as the principal source of major ions with bedrock geology governing the water chemistry. The findings of this study build on the baseline dataset for assessing future anthropogenic influence on the lake and subsequent development for future lake management strategies.

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May 2018

5 Citations

Assessment of the impacts of Trout farming on water quality using macroinvertebrates as bio-Indicators

https://doi.org/10.3126/jist.v22i2.19610

Journal of Institute of Science and Technology

Abstract

The study was conducted to assess the impacts of trout farming on water quality using macro invertebrates as bio-indicators. Two trout farms were selected for the study, viz., Gandaki Trout Farm (GTF) in Kaski district and Fall & Trout Fish Farm (FTF) in Nuwakot district. Reference and impacted sites were selected in each trout farms from where macro invertebrates were collected and physico-chemical parameters were measured. Sorensen’s Index and Multiple Site Similarity Index were calculated to compare the macro-invertebrate assemblages between the impact and the reference sites. Water quality classes were also calculated using macro invertebrate-based tool, NEPBIOS/ASPT scores. Altogether 24 families of macro invertebrates were observed at GTF and 12 families at FTF. The Sorensen’s Similarity Index was greater than 0.5 between reference and impacted sites at GTF; whereas it was only 0.28 at FTF indicating comparatively low level of similarity. In addition, Multiple Site Similarity Index (0.64) at GTF also indicated high similarity between the macro invertebrate assemblages. Reference sites showed higher scores with higher diversity of macro invertebrates. Both farms had suitable water quality for trout (dissolved oxygen and temperature) and most of the physico-chemical parameters did not show significant differences except pH and turbidity at GTF probably due to small scale operation and production.

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April 2018

Health risk assessment of atmospheric polycyclic aromatic hydrocarbons over the Central Himalayas

https://doi.org/10.1080/10807039.2018.1435254

Human and Ecological Risk Assessment: An International Journal

Carcinogenic risk assessments of polycyclic aromatic hydrocarbons (PAHs) in four sites from the Central Himalayas (Bode, Lumbini, Pokhara, and Dhunche) were performed. Lifetime Average Daily Dose (LADD), Lifetime lung cancer risk (LLCR) and Incremental lifetime cancer risk (ILCR) were calculated in order to evaluate the cancer risk. PAHs levels were converted to BaP equivalent concentrations (B[a]Peq), and models of health risk assessment were applied. B[a]Peq concentrations exceeded the standard limited value (1 ng/m3) in all the four sites. The human health risk assessment (HHRA) demonstrated high carcinogenic risk on residents of Bode and Lumbini. Further, LLCR in all sites were over the acceptable range (1.15E-03, 7.90E-04, 1.40E-04 and 9.96E-05, respectively); however, ILCR ranking exhibited acceptable range in Lumbini, Pokhara, and Dhunche (7.10E-06, 1.26E-06, and 8.95E-07). The risk variation among the sites is due to the difference in pollution status. The study shows health risk due to atmospheric PAHs via inhalation prevails all the seasons throughout, differing only seasonally; nevertheless, the concentration and carcinogenic risk decreased remarkably from south-north transect of the central Himalaya. Keeping some uncertainties aside, this study provides noble insights and helps to formulate new advance assessment on the carcinogenic risk of atmospheric PAHs over the Central Himalayas.

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February 2018

Impact Factor 2.012

Mercury concentrations in the fish community from Indrawati River, Nepal

https://doi.org/10.1007/s00128-017-2161-z

Bulletin of Environmental Contamination and Toxicology

Abstract

This study quantified concentrations of mercury (Hg) and its trophic transfer along the fish community in the Indrawati River, Nepal. Stable isotope ratios of nitrogen (δ15N) and carbon (δ13C), complemented by stomach contents data were used to assess the food web structure and trophic transfer of Hg in 54 fishes; 43 Shizothorax richardsonii and 11 Barilius spp. [B. bendelisis (1), B. vagra (3) and B. barila (7)]. Sixty-one muscle samples (including six replicates) were used for the analysis of total mercury (THg) and stable isotopes. Mean THg concentrations in B. spp. and the more common species S. richardsonii was observed to be 218.23 (ng/g, ww) and 90.82 (ng/g, ww), respectively. THg versus total length in both S. richardsonii and B. spp. showed a decreasing tendency with an increase in age. Regression of logTHg versus δ15N among the fish species showed a significant positive correlation only in S. richardsonii indicating biomagnification along the trophic level in this species.

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August 2017

2 Citations

Impact Factor 1.650

Potentially toxic trace metals in water and lake-bed sediment of panchpokhari, an alpine lake series in the central himalayan region of Nepal

Water, Air, & Soil Pollution

Abstract

This study assessed the level of potentially toxic trace metals (PTMs), seasonal variations, and their possible sources from the surface water and lake-bed sediment of Panchpokhari lake series, an alpine and glacial lake at 4160 m a.s.l. in Central Nepal. The lake series have five lakes, with Lake-1 larger than others. So, Lake-1 was investigated thoroughly during pre-monsoon and post-monsoon seasons. Sediment core was collected from the deepest basin of the Lake-1 during pre-monsoon. Most of the PTM concentrations were higher in the pre-monsoon season; however, Sc, Cr, Cu, Zn, As, and Ag were higher in the post-monsoon. This is an indication that the lake has been impacted either by natural or long-range transported atmospheric pollutants. Ti, Sb, and Ag had extremely high enrichment factor (EF) in waters, whereas Cd, Zn, and As had high EF in sediments indicating that these metals originated from anthropogenic sources. Furthermore, PTM concentrations in the sediment were in the increasing order of Hg < Cd < Ag < Mo < Sb < Sn < As < U < Sc < Co < Cs < Cu < Pb < Ni < Cr < V < Zn < Rb < Mn < Ti < Fe and showed that the upper layer (top 10 cm) of lake sediment has been receiving a higher load of PTMs in the recent period. he observed EF values also suggested that major sources of PTMs in the sediment were from crustal origin except for a few metals (Ti, V, Sb, and Ag) which were enriched anthropogenically due to long-range transport of atmospheric pollutants, deposited at the higher elevations. Nevertheless, the level of pollution in sediments was low as indicated both by EF and geo-accumulation index.

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July 2017

4 Citations

Impact Factor 1.774

Assessment of water quality and health risks for toxic trace elements in urban Phewa and remote Gosainkunda lakes, Nepal

https://doi.org/10.1080/10807039.2017.1292117

Human and Ecological Risk Assessment: An International Journal

The concentration of 13 metals (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Pb, and Hg) and their associated health risk assessment was performed for two Himalayan lakes, urban Phewa and remote Gosainkunda, from Nepal. Water Quality Index (WQI), Metal Index (MI), Hazard Quotient (HQ), Hazard Index, and Cancer Risk were calculated in order to evaluate the water quality of these lakes. Correlation analysis revealed that Mn and Fe were derived from natural geological weathering processes and Pb, V, Cr, Co, Ni, Cu, Zn, and Cd might have originated from anthropogenic sources. The results revealed that WQI of the remote lake fell into excellent water quality and urban lake fell into poor water quality, which is also supported by the MI calculation. Moreover, the HQ of Mn in urban lake showed values greater than unity suggesting its health risk to the local inhabitants. The cancer index values indicated “high” risk due to Cr, whereas Cd possesses “very low” cancer risk on local population residing nearby areas. This study provides the useful database and suggests for the regular assessment and policy formulation for safeguarding the natural water bodies in the region.

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July 2017

13 Citations

Impact Factor 2.012

1 Read

Preliminary Health Risk Assessment of Potentially Toxic Metals in Surface Water of the Himalayan Rivers, Nepal.

Bull Environ Contam Toxicol 2016 Dec 12;97(6):855-862. Epub 2016 Oct 12.

Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130, Mikkeli, Finland.

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http://dx.doi.org/10.1007/s00128-016-1945-xDOI Listing
December 2016
32 Reads
1.255 Impact Factor

Variations of the physicochemical parameters and metal levels and their risk assessment in urbanized Bagmati River, Kathmandu, Nepal

https://doi.org/10.1155/2016/6025905

Journal of Chemistry

Abstract

During post-monsoon 2013, surface water samples were collected form 34 sites from the Bagmati River and its tributaries within the Kathmandu Valley to assess the river water quality. The physical parameters were measured on site and major ions (Na+, K+, Mg2+, Ca2+, Cl, and ) and 17 elements in water were analyzed in the laboratory. Conductivity ranged from 21.92 to 846 S/cm, while turbidity ranged from 2.52 to 223 NTU and dissolved oxygen (DO) ranged from 0.04 to 8.98 mg/L. The ionic and elemental concentrations were higher in the lower section where the population density is high compared to the headwaters. The large input of wastewater and organic load created anoxic condition by consuming dissolved oxygen along the lower belt of the river. The concentration of the elements was found to be in the order of Mn > Zn > Ti > Rb > Cr > Cu > Sc > Ni > V > Li > Co > Mo > Cd > Y > Ga > Be > Nb. The concentration of Mn, Cd, Cr, Co, and Zn was particularly higher in urban and semiurban sections. Enrichment factor (EF) calculations for Cd, Co, and Zn showed their highly enriched values indicating that these elements originated from anthropogenic sources. Preliminary risk assessments were determined by the hazard quotient (HQ) calculations in order to evaluate the health risk of the metals. The  values of elements were found to be in the order Sb > Mn > Cr > V > Co > Cd > Cu > Zn > Ni > Li > Mo with all averaged HQ values less than 1, indicating no or limited health risk of metals from the river to the local residence. However the values of Sb in some parts of the Bagmati were close to unity indicating its possible threat. Anthropogenic activities like industrial activities, municipal waste water, and road construction besides the river appear to control the chemical constituent of the river water. Overall the river was highly polluted with elevated concentrations of major ions and elements and there is a need for restoration projects.

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November 2016

12 Citations

Spatial distribution, sources and risk assessment of potentially toxic trace elements and rare earth elements in soils of the Langtang Himalaya, Nepal

https://doi.org/10.1007/s12665-016-6140-1

Environmental Earth Sciences

Abstract

Soils in the fragile Himalayan region could be affected by the transport and deposition of potentially toxic trace metals (PTEs) from urban and industrialized areas of South Asia. The transported pollutants could pose a serious threat to the soil quality in the pristine regions at high elevations having minimal direct human influence. Therefore, it is important to understand the geochemical and physical characteristics of soils in this region and determine the extent of their chemical pollution. In order to achieve these objectives, soil samples were collected from different elevation transects of the Langtang Himalaya in Nepal. The samples were analyzed for PTEs and rare earth elements for the purpose of identifying their possible sources and to evaluate their environmental risk in the region. The PTEs and REEs concentrations were measured by ICP-MS (X-7; Thermo-elemental, USA) and total organic carbon (TOC) by TOC analyzer. The results of this study were comparable to those of the world average background soil as well as the Tibetan plateau surface soil. TOC revealed a decreasing trend with increasing elevation. Correlation analysis and principle component analysis (PCA) indicated that most of the elements were highly associated with major crustal elements, suggesting that their primary sources were of natural origin. Furthermore, the geo-accumulation index (I geo), enrichment factor (EF) and pollution index (PI) analyses indicated that the Himalayan soils represent minimal pollution and the data from this study may be used as background values for the Himalayan region in the future studies. REEs in the soil samples were found to be consistent with an order of average abundance of the Earth’s crust. In addition, the chondrite-normalized REE distribution of the light REE suggested enrichment of LREE and Eu depletion. Moreover, this study emphasized that soils of the Himalayan region could, in future, be under threat of elemental pollution from long-range transport via atmospheric circulation and deposition.

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October 2016

25 Citations

Impact Factor 1.871

Trace elements and organochlorine pollutants in selected fish species from Lake Phewa, Nepal

https://doi.org/10.1080/02772248.2016.1189915

Toxicological & Environmental Chemistry

Lake water and fish livers and gills of sahar (Tor putitora), spiny eel (Mastacembelus armatus), African magur (Clarias gariepinus), and tilapia (Oreochromis niloticus) from Lake Phewa, Nepal, were assessed for the concentrations of trace metals/elements and persistent organic pollutants. The lake water was neutral with low ionic and metallic concentrations as compared to high-altitude lakes of Nepal. The four elements Cu, Zn, Se, and Cd had highest concentrations in livers, indicating uptake from diet, whereas four other metallic elements Cr, Mn, Ni, and Pb had highest concentrations in gills, indicating uptake from lake water. O. niloticus tended to have most of trace metals in the liver at higher concentrations than the other species but significant differences among the different species were found only for Mn, Ni, and Zn in the gills. A pilot study on the concentrations of persistent organic pollutants in muscle revealed that dichlorodiphenyltrichloroethane and related compounds were the dominant organochlorine pesticides, having highest concentrations in C. gariepinus and lowest in O. niloticus.

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June 2016

6 Citations

Impact Factor 1.095

Atmospheric Mercury Depositional Chronology Reconstructed from Lake Sediments and Ice Core in the Himalayas and Tibetan Plateau.

Environ Sci Technol 2016 Mar 26;50(6):2859-69. Epub 2016 Feb 26.

Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences , Beijing 100101, China.

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http://dx.doi.org/10.1021/acs.est.5b04172DOI Listing
March 2016
20 Reads
1 Citation
5.330 Impact Factor

Major ions and trace elements of two selected rivers near Everest region, southern Himalayas, Nepal

https://doi.org/10.1007/s12665-015-4811-y

Environmental Earth Sciences

Abstract

During pre-monsoon of 2013, water samples were collected from 30 sites of two major rivers, viz. Dudh Koshi and Indrawati to assess the river water quality on the southern side of the Nepalese Himalayas. The physical parameters such as pH, EC, turbidity and water temperature were measured in the field and major ions (Na+, NH4 +, K+, Ca2+, Mg2+, Cl, SO4 2−, and NO3 ) and element concentrations (Li, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Cs, Ba, Pb, U, Y, Zr, Nb and Cd) in the water samples were analyzed in the laboratory. The result indicated river waters were neutral to mostly alkaline with pH ranging from 6.57 to 8.81 and EC ranging from 10.5 to 321 μS/cm. The lower values of turbidity were recorded in the pristine tributaries of Dudh Koshi, whereas the main rivers had the higher values with a range of 0.51–515 NTU. Bicarbonate (HCO3 ) showed a significant correlation with Ca2+ and Mg2+, suggesting carbonate weathering as the dominant geochemical process in the region. Furthermore, the Gibbs plot also suggested the dominance of rock weathering. Very low concentration of trace elements was found in most of the samples which were within the WHO guidelines. In addition, the concentrations of toxic elements such as As and Pb were below the detectable limits in most of the samples. Furthermore, the analysis of PCA suggests that most of the elements originated from natural weathering; however, there were some evidences of anthropogenic effect on water quality which may not be critical issue at present but can be of concern in future.

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January 2016

29 Citations

Impact Factor 1.871

Mercury and selected trace elements from a remote (Gosainkunda) and an urban (Phewa) lake waters of Nepal

https://doi.org/10.1007/s11270-014-2276-3

Water, Air, & Soil Pollution

Abstract

Two lakes, one from the remote high altitude on the southern slope of the Himalaya (Lake Gosainkunda) and another from the urban mid-hill area (Lake Phewa) were studied for evaluating anthropogenic inputs of the pollutants, particularly mercury (Hg) and other trace elements (TEs) (such as Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb). A total of 77 water samples, 24 from Lake Gosainkunda and 53 from Lake Phewa were collected from different depth profiles during October/November 2010. Concentrations of Hg were significantly higher in Lake Gosainkunda compared to Lake Phewa probably due to long-range transport of Hg and its deposition on high altitudes of the Himalayas, in addition to the probable natural geological sources. Some of the TEs (such as Al, V, Cr, Mn, Fe, and Co) show crustal origin in Lake Gosainkunda, whereas others such as Ni, Cu, Zn, Cd, and Pb indicate possible anthropogenic origin (enrichment factor (EF) > 4). On the other hand, Al, V, Cr, Ni, and Cu show crustal origin in Lake Phewa and the remaining TEs (Mn, Fe, Co, Zn, Cd, and Pb) showed high EF values relative to the crustal elements suggesting potential anthropogenic inputs of the pollutants. The study further indicates that two studied lakes have different potential sources for Mn, Fe, Co, Ni, and Cu regarding TE pollution. A high enrichment of Cd and Pb in high-altitude lake (with less anthropogenic activities) compared to the low-altitude lake (with high anthropogenic activities) indicates atmospheric long-range transportation of the pollutants in remote areas of the Himalayas which might be possible as air masses pass through the industrial areas and deposit in the high altitudes.

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February 2015

24 Citations

Impact Factor 1.774

Concentrations of trace elements in wet deposition over the central Himalayas, Nepal

https://doi.org/10.1016/j.atmosenv.2014.06.043

Atmospheric Environment

    Abstract

    Atmospheric pollutants transported from south Asia may impose a serious impact on human and ecosystem health in the central Himalayan region, Nepal. In order to investigate trace elements in atmospheric wet deposition in the southern slope of the Himalayas, precipitation samples were collected for over a year from four stations: Kathmandu (1314 m.a.s.l), Dhunche (2065 m.a.s.l), Dimsa (3078 m.a.s.l) and Gosainkunda (4417 m.a.s.l) characterized as urban, semi-urban, rural or remote site, respectively. A total of 221 samples were collected and concentrations of 10 trace elements (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) were examined. The highest concentrations of elements were found at urban site (Kathmandu) and lowest at remote site (Gosainkunda). The seasonal differences of elemental concentrations in Kathmandu was not clear between monsoon and non-monsoon seasons as local sources predominated over regional sources. On the contrary, the other three sites showed a distinct seasonal variation with higher loadings of trace elements during non-monsoon and lower during monsoon. EFs calculations at all sites showed that most of elements (Cr, Co, Ni, Cu, Zn, Cd and Pb) were from anthropogenic sources and some (Al, Fe and Mn) were originated from crustal sources. Furthermore, principal component analysis (PCA) also indicated that the precipitation chemistry was mostly influenced by crustal and anthropogenic sources in Nepalese Himalayas. The result from the present study is an indication that long-range transport of pollutants has a significant impact on the high altitude remote areas in the central Himalayan regions.

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    October 2014

    55 Citations

    Impact Factor 4.012

    The risk of mercury exposure to the people consuming fish from Lake Phewa, Nepal.

    Int J Environ Res Public Health 2014 Jun 27;11(7):6771-9. Epub 2014 Jun 27.

    Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli, Finland.

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    http://dx.doi.org/10.3390/ijerph110706771DOI Listing
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4113843PMC
    June 2014
    6 Reads
    1 Citation
    2.063 Impact Factor

    Mercury concentrations in commercial fish species of Lake Phewa, Nepal.

    Bull Environ Contam Toxicol 2013 Sep 10;91(3):272-7. Epub 2013 Jul 10.

    Key Laboratory of Tibetan Environmental Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing, China.

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    http://dx.doi.org/10.1007/s00128-013-1055-yDOI Listing
    September 2013
    23 Reads
    1 Citation
    1.255 Impact Factor

    Physico-chemical characterization of Gosainkunda Lake

    https://doi.org/10.3126/njst.v13i1.7449

    Nepal Journal of Science and Technology

    Abstract

    High altitude lakes are very sensitive to climate change due to their small catchment area, limited vegetation cover, surface water with low nutrients, and thin soil and low bedrock weathering rates. The present study was focused on high altitude Himalayan Lake Gosainkunda, situated at an elevation of 4300 m in the Langtang National Park, and carried out during the post- monsoon season (October) in 2010. The main aim of the study was to assess the water quality quantitatively considering the anthropogenic as well as natural impacts in the lake. The water samples were collected at six different sites to represent entirely the quality of the lake. The sampling sites were systematically designated as the inlet, outlet, human influence site, littoral zone, middle (central) and the deepest part of the lake. Some major cations (Ca++, Mg++, Na+ & K+) and anions (Cl-, SO4 & HCO3-) were analyzed; the cation type is dominated by Ca++ (64%) while the anions are dominated by Cl- (49%). Among the trace elements (Al, Fe, Mn, Zn, Cu, Cd, Cr, Ni, Pb & As), except for Al and Fe, all others were found below the detection limit.

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    January 2013

    10 Citations

    2 Reads

    Effectiveness of rare earth elements constrain on different materials: a case study in central Asia

    https://doi.org/10.1007/s12665-012-1586-2

    Environmental Earth Sciences

    Abstract

    Rare earth elements (REE) have been extensively used to indicate for material provenance since they behave conservatively and mainly transport in particulate form during earth surface processes. Nevertheless, the application of REE for material provenance study has to be cautious because grain size and mineral fractionations can alter bulk compositions of weathered sediments. Central Asia is one of the most important dust source regions globally and numerous studies on REE compositions of surface materials have been conducted. In this study, REE compositions of various materials from this area are summarized to explore the existing REE-related problems. Overall, chondrite-normalized REE patterns for many surface materials are so uniform that they cannot serve as reliable approaches in tracing material source regions. In contrast, great variations of REE compositions occur among different materials that are derived even from the same parent rock due to influences of grain-size distributions and heavy minerals. For the same reason, small-scale loess around the Tibetan Plateau has different upper continental crust (UCC)-normalized REE patterns compared to those of typical loess. Therefore, great cautions should be made when UCC-normalized REE patterns and REE ratios are utilized to investigate material provenance. Finally, some suggestions are proposed for such studies in future.

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    February 2012

    2 Citations

    Impact Factor 1.871

    Bioaccumulation of organochlorine pollutants in the fish community in Lake Arungen, Norway.

    Environ Pollut 2009 Aug-Sep;157(8-9):2452-8. Epub 2009 Mar 28.

    Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 As, Norway.

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    http://dx.doi.org/10.1016/j.envpol.2009.03.007DOI Listing
    December 2011
    10 Reads
    4.143 Impact Factor

    First results on bathymetry and limnology of high-altitude lakes in the Gokyo Valley, Sagarmatha (Everest) National Park, Nepal

    https://doi.org/10.1007/s10201-011-0366-0

    Limnology

    Abstract

    The aim of this study was to investigate for the first time the morphology, physical and chemical characteristics of three high-altitude lakes in the Gokyo Valley, Everest National Park, Nepal. The moraine-dammed glacial lakes were studied for three seasons to create baseline data. The second, third, and fourth lakes in the Gokyo Valley are deeper than previously assumed. The vertical profiles of temperature and dissolved oxygen indicated that the thermocline zone varied between 10 and 20 m below the surface during the post-monsoon season. Although most of the analyzed metal concentrations were below the level recommended by the WHO for safe drinking water, lead (Pb) and cadmium (Cd) levels exceeded the limits in some of the samples. This has created great concern for human health. The probable route of these two pollutants is monsoon precipitation that carries industrial pollutants along its route. The sedimentation rates of Gokyo Lakes range from 0.069 to 0.089 cm per annum, which is within the limits of other high-altitude lakes. The present findings created a baseline database for some of the remote high-altitude lakes in Nepal that can be used for lake management and for assessing future changes in lake characteristics in the Himalayan region.

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    December 2011

    16 Citations

    Impact Factor 1.691

    The genus Cymbopleura (Cymbellales, Bacillariophyta) from high altitude freshwater habitats, Everest National Park, Nepal, with the description of two new species

    10.5507/fot.2011.025

    Fottea

    As part of a study on the diatom flora of the Gokyo Valley, Everest National Park, Nepal, eleven species of Cymbopleura (Bacillariophyta), including two new species, Cymbopleura gokyoensis Jüttner et Van de Vijver sp. nov. and Cymbopleura emoda Jüttner et Van de Vijver sp. nov., were investigated using light and electron microscopy. Some taxa could not be identified with certainty using the currently available literature due to small differences in valve dimensions, raphe structure and striation patterns. It remains unclear whether they represent new species or whether the original descriptions should be emended to include the populations from Nepal.

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    September 2011

    11 Citations

    Impact Factor 1.727

    Heavy metals in sediments of the Yarlung Tsangbo and its connection with the arsenic problem in the Ganges-Brahmaputra Basin.

    Environ Geochem Health 2011 Feb 7;33(1):23-32. Epub 2010 May 7.

    Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, CAS, 100085 Beijing, China.

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    http://dx.doi.org/10.1007/s10653-010-9311-0DOI Listing
    February 2011
    24 Reads
    2.570 Impact Factor

    Oricymba (Cymbellales, Bacillariophyceae), a new cymbelloid genus and three new species from the Nepalese Himalaya

    https://doi.org/10.2216/09-77.1

    Phycologia

    A new genus Oricymba is described with its type species based on Cymbella japonica Reichelt. In addition, three new species are described from the Nepalese Himalaya: O. subaequalis, O. latirotundata and O. subovalis. The new genus has slightly dorsiventral or almost symmetrical valves with polar raphe endings deflected to the dorsal side. It can be distinguished from other cymbelloid genera by two morphological characters. There is a ridge along the valve face: mantle junction, and areolae are slit-like and partially occluded by dentate projections. To date Oricymba has been found only in often nutrient-poor, freshwater habitats of the Indian subcontinent, Southeast Asia, Korea and Japan.

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    September 2010

    47 Citations

    Impact Factor 1.976

    Increased population density of pike Esox lucius– a result of selective harvest of large individuals

    https://doi.org/10.1111/j.1600-0633.2008.00310.x

    Ecology of Freshwater Fish

    Abstract – The effect of selective harvest of large pike on number of middle‐sized pike was tested in a small, eutrophic lake in SE Norway. The pike population was estimated using a mark–recapture method in two different periods: before (1980–1983) and during the manipulation of the pike population (2004–2006). After an extensive size selective harvest of large pike (≥65 cm) in 2004, the number of pike in length‐class 45–65 cm, mainly 3+ pike, increased significantly from 2004 to 2005. The number in this length‐class was even higher in 2006. Since 2+ pike was part of the diet of large pike, the increase in number of 3+ pike in 2005 and 2006 is probably due to reduced consumption of 2+ pike, following the substantial selective removal of large pike in 2004 and 2005. To maintain a high annual survival of young pike, a selective exploitation of large pike has to be carried out annually.

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    December 2008

    24 Citations

    Impact Factor 1.742

    Freshwater fishes, fisheries, and habitat prospects of Nepal

    https://doi.org/10.1080/14634980802317329

    Aquatic Ecosystem Health & Management

    This paper deals with the status of fish, fisheries, and habitats in Nepal. Being a landlocked country, it has only freshwater habitats covering an area of 745,000 hectares (5% of the total area) that includes rivers, lakes, ponds, wetlands, reservoirs, and irrigated rice fields. It has a diverse fish species totaling 200 fish species, of which 191 are indigenous and nine exotic. Thirty-four fish species were categorized as threatened (IUCN categories), requiring due attention for the conservation. Legal protection is recommended for ten fish species in the endangered and vulnerable categories. Fish harvests are mainly based on the subsistence fish farming, and from capture fisheries. National fish production in the year 2000/01 was 33,270 metric tons. Lowland areas are most suitable for aquaculture, whereas hill streams have a great attraction for sport fishing. Some destructive fishing methods are in use in capture fishery, e.g., electric fishing, explosives and poisons. In Nepal, some of the major fish habitats are in protected conservation areas, e.g., national parks and World Ramsar Sites. However, proper consideration has not been given for fish habitat management. The national plan includes a fisheries/aquaculture sub sector mainly for supplying animal protein, and for generating self-employment and income of small-scale farmers. The number of people involved in the capture fisheries has increased and included 142,000 men and 223,000 women in the year 2000/01. At the same time, commercial trout farming in the private sector has increased. Long-term perspectives in the fields of aquatic ecology, genetics, biotechnology and ecotoxicology are essential to enhance the fish and fisheries science in the country.

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    August 2008

    18 Citations

    Impact Factor 0.876

    1 Read

    Selective exploitation of large pike Esox lucius--effects on mercury concentrations in fish populations.

    Sci Total Environ 2008 Jul 15;399(1-3):33-40. Epub 2008 May 15.

    Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 As, Norway.

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    http://dx.doi.org/10.1016/j.scitotenv.2008.03.026DOI Listing
    July 2008
    9 Reads
    1 Citation
    4.100 Impact Factor

    Shift in density, habitat use, and diet of perch and roach: an effect of changed predation pressure after manipulation of pike

    https://doi.org/10.1016/j.fishres.2007.11.011

    Fisheries Research

    Abstract

    Density, diet, and habitat use of roach (Rutilus rutilus) and perch (Perca fluviatilis) were studied in Lake Årungen before (1978–1982) and after (2004–2006) an extensive exploitation of large pike (Esox lucius). The relative density of small roach and perch was significantly decreased while the relative density of young pike increased substantially. Habitat overlap between roach and perch was high during 1978–1980 compared to 2005–2006. However, they were segregated in diet in both periods, but showed a considerable shift in diet after the manipulation. Roach changed its diet mainly towards detritus and zooplankton. Perch utilized more zooplankton and fish. The increased use of zooplankton indicates large zooplankton abundance, probably due to reduction of small roach and perch as a result of increased number of piscivorous pike and perch. Indirectly, a manipulation of large pike in small eutrophic lakes with simple fish communities as in Lake Årungen may have a cascading effect on the biotic community, and thus be a managing tool in restoration.

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    May 2008

    38 Citations

    Impact Factor 2.343

    Age determination and backcalculation of pike length through use of the metapterygoid bone

    https://doi.org/10.1111/j.1095-8649.2007.01435.x

    Journal of Fish Biology

    Abstract

    The validity of the metapterygoid bone of pike Esox lucius for use in age determination and backcalculation of total length (LT) was evaluated by using tagged pike recaptured after 4 months to 3 years. A regression equation for the relationship between pike LT and metapterygoid length was estimated, and no significant deviations between the backcalculated and expected LT at tagging were found for recaptured pike. The results confirm that 1) the checks are formed annually and 2) no false checks appeared on the metapterygoids of pike.

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    May 2007

    9 Citations

    Impact Factor 2.038

    1 Read

    Impacts of a small dam on macroinvertebrates: A case study in the Tinau River, Nepal

    https://doi.org/10.1080/14634980500218332

    Aquatic Ecosystem Health & Management

    Macroinvertebrate composition, eco-morphological habitat descriptions and substrate composition were assessed above and below a small dam in the Tinau River, Nepal to explore the impact of the dam on biotic conditions. Four sites, one about 1.5 km above, one just above the dam site, one just below, and one about 2.5 km below the dam, were selected for qualitative and quantitative samplings of macroinvertebrates. The Nepalese Biotic Score method was used for the biological water quality assessment. The most abundant groups of macroinvertebrates among the total collection were of the family Chironomidae (53.5 percent) followed by Ephemeroptera (36 percent) and Trichoptera (5 percent). Only one of the dominant families, Baetidae, showed significant variability with substrate composition. The dam building had significant impacts on the macroinvertebrate composition just above the dam site, probably as a result of deposition of inorganic material within the small reservoir and changes in water speed. Damming of the Tinau River thus seems only to have a relatively minor impact on the river biota downstream of the dam site. The water quality of the river was assigned as Class II in all the stations, indicating its suitability for drinking after treatment.

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    July 2005

    29 Citations

    Impact Factor 0.876

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    Dipesh Rupakheti
    Dipesh Rupakheti

    Chinese Academy of Sciences