Occurrence of fluoride in the drinking waters of Langtang area, north central Nigeria

The aim of the study is to assess the occurrence of fluoride in the drinking water sources of Langtang area. Out of the thirty seven water samples collected from drinking water sources (hand dug wells, boreholes, streams and a spring) and analysed. Results revealed that except for fluoride, all other parameters are within the World Health Organisation recommended limits for water consumption. Fluoride in the waters ranges from 0.12 - 10.30 mg/l with a mean of 2.42 mg/l. low levels of fluoride are recorded in the stream samples. However, no clear variations in fluoride content have been observed in both the borehole samples and those from the hand dug wells. Negative correlation exhibited between fluoride and sulphate, fluoride and Phosphate and the poor correlation between fluoride and nitrate, fluoride and chloride rules out the possibility of anthropogenic source of the fluoride in the waters. Positive correlation between lithium and magnesium, and poor but positive correlation between fluoride and lithium indicate that micas within the host rock and the pegmatite may be responsible for leaching fluoride into the waters. Two of the major water types;Ca + Mg-HCO3 and the Na + K-HCO3 water type obtain in the area have good association with fluoride content. Consumption of high fluoride waters clearly manifests in the inhabitant of the area in form of dental fluorosis and bowing of legs especially in children between the ages 7 - 11 years.

Controls on Gosaikunda Lake Chemistry within Langtang National Park in High Himalaya, Nepal

Surface water samples and lake bed sediments were collected and analyzed from Gosaikunda Lake within Langtang National Park (28°05'N, 85°25'E;4380 m a.s.l.) in the central Himalayan region of Nepal during fall 2011. The major cations and anions in equivalents were present in the following order: ?and , respectively. Sulfide oxidation coupled with carbonate dissolution and aluminosilicate dissolution appeared to be the dominant geochemical processes determining lake water dissolved ions. Sulfate concentration was much higher than the alkalinity which is in contrast to glacier meltwater within the same landscape. Alkalinity primarily as bicarbonate contributes 88.6% to the total dissolved inorganic carbon (DIC) followed by carbon dioxide (CO2) and carbonate (CO3) in surface water samples. Organic carbon contributes 0.3% to 5.4% to the sediments and the organic matter is predominantly of aquatic origin. The lake is under saturated with carbon dioxide and the average partial pressure of carbon dioxide (pCO2) appeared quite low (43.4 μatm). Overall, natural biogeochemical processes regulate the chemical species within the lake ecosystem. The lake is oligotrophic, however, nutrients and dissolved organic carbon (DOC) concentrations are enhanced at the near shore sites close to the tracking trail.

Hydro-Chemical Characterization of Glacial Melt Waters Draining from Langtang Valley, Nepal

A detailed analytical study of the physico-chemical parameters of melt water draining from glaciers of Langtang Valley with an elevation ranging from 1395 m a s l to 4200 m a s l in Rasuwa district, Nepal was carried out in order to study the seasonal and altitudinal variation in hydro-chemistry along the Langtang River and glacial melts from the Lirung and the Khimsung Glaciers. The study was carried out during 6 - 10 April and 30 June-3 July, 2014 at 11 sites. A total of 22 composite samples were collected. The concentration of cations and anions of the Langtang Valley were found in the order Ca2+ > K+ > Na+ > Mg2+ and , respectively. Significant seasonal variation in electrical conductivity (EC), turbidity, dissolved oxygen (DO), calcium (Ca), sodium (Na), magnesium (Mg), chloride (Cl), sulphate (SO4) and total phosphorus (TP-PO4) and altitudinal variation in EC, total dissolved solids (TDS), DO and Na was found out. The concentrations of the heavy metals (As, Al, Mn, Zn, Cd, Cr) were below the detection limit except Fe (0.5 to 18.1 mg/l), which was highly variable. Calcium carbonate weathering was found out to be the major source of dissolved ions in the region. The elemental ratios (Ca/Si and K/Na) were typical of glacial melt water and the low Na/Cl and K/Cl ratios indicated major contribution from atmospheric precipitation to the observed dissolved ions of melt waters. The study showed an increase in the concentration of cations as compared to previous studies, which could be attributed to increasing weathering rates due to temperature increase. Elevated concentration of NO3 and TP-PO4 compared to previous studies show the effect of human impact in the region. Differences in the melt water composition between the debris covered and clean type glacier was found out.

Assessment of Sediment Load of Langtang River in Rasuwa District, Nepal

This paper assesses the sediment load of the glacier fed Langtang River, Nepal from April 2014 to March 2015. Water samples were collected from the centre of the river with a frequency of two samples per each sampling day using the Depth Integration Technique (DIT) on daily basis in the monsoon season, weekly in the pre- and post-monsoon seasons and bi-monthly in the winter season. Suspended sediment concentration (SSC) is calculated from the water samples using filtration followed by oven-drying, and a rating curve is used to calculate daily discharge of the Langtang River. The annual sediment yield is 109,276.75 tons and 37.69, 11.52 and 5.54 tons of sediment is transported per day in the pre-monsoon, post-monsoon and winter seasons, respectively. There is a very high value of 872.86 tons per day in the monsoon season, which contributes the highest sediment load among all of the seasons comprising 83% of the total sediment transport. Diurnal cycle of sediment discharge is clearly seen with higher sediment discharge during the evening than the morning and reaching maximum values of 41.1 kg·s-1 and 61.5 kg·s-1, respectively. A clock-wise hysteresis loop has been obtained for discharge and sediment discharge where sediment flux is higher in the early monsoon than in the late monsoon for a corresponding discharge.

Sustainability of Transhumance Grazing Systems under Socio-economic Threats in Langtang,Nepal

The decline or loss of traditional socialecological systems may induce adverse effects to the societies and ecosystems. Transhumance, the recurring and seasonal movement of grazing livestock, is increasingly constrained by a numbers of factors including policy, land use and socio-economic changes in Nepal. To explore how these changes have affected the transhumance, this study investigated transhumance at the Langtang valley in central Nepal. The specific objectives of this study were to determine the herd size and composition, spatial-temporal patterns and to identify the major drivers of the system and the system changes. Data were collected from field study comprising semi-structured interviews with the herders, focus group discussions, key informants survey, and observations of rangeland and livestock management systems. The study revealed that the transhumance system in the Langtang is influenced by two types of drivers. In one hand, traditional practices are contributing to the sustainability of the system. On the other hand, the grazing patterns and adaptive responses are strongly influenced by changes in government policies, socioeconomic and cultural transformation, livestock productivity, markets, rangeland conditions and climate change. The findings of this study help with the development and implementation of transhumance management policy for the sustainability.

Unravelling the linkages of cryosphere and mountain livelihood systems:A case study of Langtang,Nepal

Globally,mountains are often characterized as fragile and hazardous terrains,with vast areas covered by the cryosphere.The livelihoods of communities in the Hindu Kush Himalayan region are closely linked with the cryosphere.But over the past few decades,communities in the region have experienced multiple changes,including those driven by climat e change,with direct and immediate impacts on their lives and livelihoods.In this study,we explore linkages between the cryosphere and high-mountain livelihoods using a social-ecological system approach.It examines how the complex social-ecological system in villages in Langtang Valley,Nepal,has evolved in response to both cryospheric and socioeconomic changes.The local communities perceive gradual but significant changes in the cryospheric system,such as receding and thinning glaciers,changing snowfall patterns,changes in temperature and precipitation patterns,and a growing incidence of cryosphere-related hazards,such as avalanches and landslides.Communities in the Langtang Valley are also facing a number of socioeconomic changes,resulting in changing aspirations,particularly among the youth.The growing disconnection between society and the surrounding cryosphere,with direct impacts on the transfer and growth of local knowledge systems,are discussed.These simultaneous changes in the cryosphere and the socioeconomic domain have also resulted in a homogenization of livelihood sources,with tourism emerging as the dominant source of livelihood.This has resulted in a dependence of the local population on food imported from outside the valley.A growing dependence on tourism for livelihoods,dependence on imports for food and other basic needs,and the lack of a risk reduction strategy might pose great risks for local lives and livelihoods in the long run.Interventions pertaining to diversifying livelihoods,harmonizing social capital,and hazard risk assessment are essential for strengthening linkages between cryosphere and the socioeconomic system.