Phosphorus and nitrogen in the waters of the El-Kabir River watershed in Syria and Lebanon

In order to assess the quality of the waters of the El‐Kabir River, which forms the border between Lebanon and Syria, water samples were collected for phosphorus (P) and nitrogen analyses at 39 sample stations in the river watershed (18 in Syria, 21 in Lebanon). These samples were collected on the main stem and three major tributaries (Nahr al‐Arous and Nahr Nasrive in Syria, Chadra River in Lebanon). Three major springs also were sampled. The sampling was carried out in September 2001, and January, April and August 2002. Nutrient analyses were carried out on samples taken in September 2001, January and April 2002 in Syria, and in September 2001 and August 2002 in Lebanon. The P concentrations were extremely high throughout the watershed, as were the ammonia‐nitrogen and nitrate‐nitrogen concentrations, indicating extensive pollution. Although the nitrite‐nitrogen concentration was relatively low, it is at the upper end of what might be considered normal, thereby perhaps being indicative of some anthropogenic sources. The spring waters were found to be polluted by nutrients. The nutrient sources contributing to the river pollution were mainly from piped, direct sewage discharges from the many settlements throughout the basin. These were supplemented by diffuse sources directly from agricultural fertilizer use and from the indiscriminate disposal of solid wastes into the river and on the stream banks and lands adjacent to the roads of the watershed.     

Hydrological and watershed characteristics of the El-Kabir River, North Lebanon

The El‐Kabir River watershed is the largest in western Lebanon and is shared between Lebanon and Syria. The river forms most of the northern boundary of Lebanon with Syria, being characterized by water flow throughout the year. The characteristics of the river and its variable hydrologic properties are the result of abrupt changes in land physiography. Until recently, data on Lebanese rivers was inadequate, especially for rivers shared with other countries. The El‐Kabir River watershed typifies this situation, particularly when the river has undergone many changes, including water pollution and declining discharge because of changing climate and increased pollution. This study was implemented in the context of a large investigation of the watershed which was funded by the International Development Research Council, Canada, for the purpose of improving the baseline data and knowledge required to effectively manage this important resource. Within the water cycle, ≈ 250 × 10⁶ m³ of precipitation falls on the Lebanese side. Of this volume, ≈ 50% is lost as evaporation and transpiration, while 5–50% of the remainder infiltrates to ground water, with the residual becoming land run‐off. An obvious decline of ≈ 40% of the total river discharge of the river has occurred over the last 50 years. It can be explained by climate change and by water extraction associated with dramatic increases in population and associated land uses. The hydraulic configuration and characteristics of the river have two major orientations; namely, NE–SW and E–W. These orientations are the product of geological structure and lithologies. Furthermore, each has different hydrologic properties related to watershed size, elevation, slope, catchment shape and orientation, although both orientations are directly inter‐related.     

Environmental management of the waters of the El-Kabir River and the associated Akkar watershed

The Akkar watershed of the El‐Kabir River forms the northern boundary of Lebanon with Syria and drains into the Eastern Mediterranean Sea. This paper endeavours to provide a management plan tailored to the issues and needs of the Akkar watershed. It is not designed as a simplistic workbook of procedures but as a series of broad, thematic recommendations addressing the environmental problems identified by technical studies and interaction with the inhabitants of the watershed. It outlines a three‐phase (short, medium and long‐term) approach to address public health and water sustainability in the context of an enduring management system. In all phases, a set of underlying principles are utilized which incorporate a watershed approach, collaboration and cooperation, sustainability, a balance between water quantity and quality, equity and public involvement.     

Bacterial indicators of faecal pollution in the waters of the El-Kabir River and Akkar watershed in Syria and Lebanon

Water samples for bacterial analyses were taken, when possible, at 41 sites in Lebanon and Syria in the El‐Kabir River watershed. Samples were analysed for total coliform (TC), faecal coliform (FC) and faecal streptococcus. The Lebanese samples also were analysed for the presence of sulphate‐reducing bacteria. The TC and FC concentrations were extremely high throughout the watershed, rendering the water unfit for any human uses. The origin of the bacteria is the untreated sewage waste from the numerous settlements situated throughout the watershed. This primary origin is supported by high ratios of FC/faecal streptococcus, although impacts from animal wastes also were observed. The bacterial levels were higher in summer than in winter, indicating a high winter river flow that dilutes a relatively constant source of human sewage discharged to the system. Spring waters also exhibited elevated levels of bacteria, implicating surface land use and waste disposal practices upstream of the springs. The data clearly shows that human health is at a high risk and that strategies for improving water quality and protecting spring water must be expeditiously implemented.     

Watershed characteristics, land use and fabric: The application of remote sensing and geographical information systems

Integrated watershed assessment, especially relying on remote sensing (RS), is a newly established procedure in developing countries. It is proving to be a major component in river‐basin environmental management. The recurrence of environmental problems in the Akkar El Kabir River watershed, as well as the lack of proper data on sources and sinks of pollutants, and the extent of human interference, led to the current study. Advanced geoinformation tools, such as RS and geographical information systems (GIS), prove to be a valuable asset in securing data on the fabric of the Akkar watershed in relation to its natural setting and anthropic interference. This is particularly true in the current study as the river constitutes the boundary between Lebanon and Syria. Remote sensing captures the watershed characteristics and land use on both sides without constraints. The natural fabric includes geology, drainage, hydrogeology, forest and soil. The anthropic fabric includes settlements, utilities, roads, agriculture and land use. If it were not for geoinformation techniques, the task of securing such data would be difficult. Also, these techniques show the impact of malpractices from excessive human interference that result in degradation of land and water quality. Changes in the watershed, such as environmental deterioration, are observed as water pollution, soil erosion, forest decline and socioeconomic imbalance. Obviously, this is the outcome of malpractices in a multisectorial system. A major challenge for RS and GIS is to quantify, model and predict, if possible, the extent of these changes. Remote sensing inherently captures the impact of interaction between nature and human beings. Detection of change is a major indicator that RS can contribute to the evaluation of the state of the environment. The application of it on this watershed reveals that significant changes have occurred over the last 10–15 years, most of which are anthropic.     

Groundwater recharge and pollution in Wadi El‐natrun,Egypt

The isotopic compositions of deuterium, oxygen‐18, tritium and nitrogen‐15 were determined for some groundwater samples from Wadi El‐Natrun area. The distribution pattern of the environmental isotopes could be explained by the differences in the degree of mixing between three major sources of recharge to the Wadi El‐Natrun aquifer: River Nile water, paleowater and drainage water from Nubarya reclamation project. The analysis of ¹⁵N‐nitrate indicates a mixing process     

Long‐term irreversible changes in a lake ecosystem affected by the Indian Ocean Tsunami

This study focused on ecosystem responses to the environmental perturbations caused by the 2004 Indian Ocean Tsunami in a small lake that was a freshwater body in 1996, prior to the tsunami. The physicochemical and biological characteristics of Kokilamedu Lake (KKM) revealed drastic changes, compared with pretsunami conditions. Monthly average observations on water quality indicated the electrical conductivity of the water increased steeply to 17.41 mS cm^?1 in 2009, from the lowest pretsunami value of 1.83 mS cm^?1 (range of 1.83–5.25 mS cm^?1). Simultaneously, the nitrate + nitrite (NO₃ + NO₂) values increased significantly from 0.49 μmol L^?1 in 1996 to 74.47 μmol L^?1 in 2006. Silicate (SiO₄‐Si) exhibited a dramatic increase in concentration, from an average of 64.87 μmol L^?1 in the pretsunami period to 309.71 μmol L^?1 the post‐tsunami period (2009–2010). Inorganic phosphate had increased to a maximum of 9.59 μmol L^?1 from a pretsunami maximum of 1.09 μmol L^?1. The chlorophyll‐α concentrations did not respond to the increased nutrient stoichiometry of the lake. There was a decreased chlorophyll‐α concentration under post‐tsunami conditions. The recent infilling of the lake with sediment during the tsunami, associated with wind‐driven resuspension reduced the light penetration. There was a significant improvement in dissolved oxygen concentrations (2006–2010 average of 8.27 mg L^?1) in the lake, however, compared with the pretsunami values (1994–1995 average of 5.94 mg L^?1). The algal component is now dominated by blue‐green algae, while green algae had dominated in the pretsunami period. Pre‐ and post‐tsunami observations from a control site did not exhibit such dramatic shifts from the 1995 and 1996 conditions, whereas a shift was apparent in the case of KKM. Certain marine fishes have adapted to this altered ecosystem. These marine species encountered (Elops machnata, Cociella punctata, Sphyraena jello, Platycephalus indicus, Glossogobius giuris) might have been recruited during the intrusion of the tsunami waves.     

Stratification and water quality of an abandoned opencast coal pit lake at Raniganj Coalfield Area,West Bengal,India

Stratification and assessment of the limnological conditions of an abandoned opencast coal pit (OCP), locally called Khadan, which is a potential water reserve located at the Raniganj‐Asansol Coalfield Areas of Burdwan, are the main objectives of this study. Water quality changes occurred with increasing depths in the OCP water and suggest a gradual and significant ecological restoration over time, which can create a condition of sustainable pisciculture. The physical and chemical variables of the OCP water changed with changing depths and seasons. The temperature and alkalinity decreased with depth throughout the year. The dissolved oxygen concentration exhibited a mixing characteristic in the summer and winter, but decreased with depth in the monsoon and postmonsoon seasons. The total hardness increased with depth in the monsoon season, being maximum in the winter (196.0 mg L^?1). The biochemical oxygen demand (BOD) and chemical oxygen demand (COD) increased with depth in the winter. The silicon concentration increased with depths, exhibiting a maximum value of 14.2 mg L^?1 in the winter and a minimum value of 1.24 mg L^?1 in the postmonsoon season. The ammonia‐nitrogen, nitrate‐nitrogen, potassium, chloride and sulphate concentrations only exhibited seasonal variations. The concentration of heavy metals (arsenic, chromium, cadmium, manganese) decreased with increasing depth. The fluoride concentration exhibited high concentrations in each OCP water layer. The results of this study indicated that limnological variables in thermally stratified lakes may be an important measure for better understanding the gradual process of developing an improved ecological conditions in the OCP and which can facilitate the possibility of pisciculture in the near future.     

Sensitivity of water quality indicators in a large tropical reservoir to selected climate and land‐use changes

This study compared the sensitivity of water quality in tropical Aguamilpa Reservoir, as represented by normalized algae mass and dissolved oxygen, to selected projected changes from global climate change and development. The sensitivity of reservoir stratification as an indicator of reservoir sensitivity also was analysed. Model simulations indicated the reservoir was more sensitive to changes during the warm‐dry season than at other times. Both indexes (normalized algal mass and dissolved oxygen mass) were more sensitive to changes in air temperature (climate change) and nitrogen loading (development) than to changes in flow. The sensitivity to air temperature was similar to, but generally less than, the sensitivity to nutrient inflow. At the bounding values for change (3 °C for temperature; 50% increase in nitrogen loading), the algae mass sensitivities were 0.15 mg L^?1 per 3 °C and 0.2 mg L^?1 per 50% nitrogen load increase, and the dissolved oxygen mass sensitivities were 0.7 mg L^?1 per 3 °C and 2.0 mg L^?1 per 50% load increase. Changes in air temperature and nitrogen loadings affect the reservoir in different ways, air temperature mostly changing the timing of the algal growth with little change in peak values, while nutrient loadings change the peak values with little change in the timing. While the sensitivities are similar, the total algal mass change is significantly larger for nitrogen loading, compared to air temperature changes. These results imply global climate change effects can be partially mitigated by implementing management measures in the surrounding watersheds to minimize nutrient inflows, especially nitrogen in the case of Aguamilpa Reservoir.     

Stratification,diel and seasonal energy transfers in Malilangwe Reservoir in the south‐eastern lowveld of Zimbabwe

This study provides a 9‐month record of Malilangwe Reservoir stratification and diel and seasonal energy transfers between February and October 2011. The reservoir was not strongly stratified during the hot‐wet season (February and March), exhibiting low dissolved oxygen concentrations of <2 mg DO L^?1 in the bottom layers (<6 m depth). During the cool‐dry season, when both the air temperature and solar radiation input decreased, the water temperatures in the epilimnion and across the thermocline decreased, and the water column was very weakly stratified. In this state, the reservoir could easily be mixed, even by light winds, resulting in overturning, thereby giving the bottom water an opportunity to become aerated, as observed during the cool‐dry season. The stability was greatest when the water level was high (during midday), while it was considerably lower during the predawn hours. The calculated annual Birgean heat budget for the reservoir was 110 MJ m^?2 year^?1 for February to October 2011. The diurnal Birgean heat budget was consistently associated with heat loss over a 24 hour period in all seasons, mostly between 0400 and 1000 h. Spearman's correlation suggests that the DO was significantly correlated with stability for the three study months (February r = 0.69, P < 0.05; June r = ?0.76, P < 0.001; October r = 0.96, P < 0.001). The results of this study suggests that warming temperatures (warmer months or seasons) will result in high Birgean heat budgets, which could potentially trigger some important changes in plankton population dynamics in small reservoir, with severe water quality implications. The nutrient concentrations varied throughout the seasons.     

Eutrophication of lakes in urbanized areas: The case of Yaounde Municipal Lake in Cameroon, Central Africa

A 1 year qualitative and quantitative evaluation of phytoplankton and chlorophyll‐a, as well as some physicochemical parameters, was recorded in a shallow tropical lake in Cameroon: the Yaounde Municipal Lake. Physicochemical measurements also were regularly made in its main tributary (Mingoa Stream). These analyses aimed to assess the lake's trophic status and to propose measures for controlling its degradation process. The Secchi disk transparency was low and rarely exceeded 100 cm. Conductivity was higher near the lake bottom. The oxygen deficiency, and sometimes anoxia, recorded from a 2.5 m depth leads to high quantities of ammonium‐nitrogen. The total phosphorus concentrations varied from 80–2290 µg P L^?1 and the total Kjeldhal nitrogen concentrations fluctuated between 3 and 15 mg  L^?1. Upstream to the lake, in the Mingoa Stream, total phosphorus concentrations ranged from 0.6–3.8 mg P L^?1 and total Kjeldhal nitrogen concentrations ranged from 10–22 mg  L^?1. There are up to 102 phytoplankton‐specific taxa, with Euglenophyta and Chlorophyta particularly more diversified. The phytoplankton biomass and chlorophyll‐a concentrations reached 225 µg mL^?1 and 566 mg m^?3, respectively. The analyses pointed out the allogenic nature of the functioning of this ecosystem as a result of bad waste management in the surrounding landscape. Urgent actions need to be undertaken in order to rehabilitate this lake, which rapidly shifted to a hypertrophic status.     

Geochemistry of the sediments of the El-Kabir River and Akkar watershed in Syria and Lebanon

A total of 39 sediment samples were collected from the El‐Kabir River and its major tributaries during the low‐flow period of August/September 2001. Of these samples, six were selected for a scan for pesticide residues, polychlorinated biphenyls and polycyclic aromatic hydrocarbons (PAHs). An additional seven samples were analysed for major elements and trace elements. Despite the limited number of samples analysed, it can be concluded that major elements reflect the distribution and chemistry of major rock types in the watershed, the sodium oxide concentrations indicate an early onset of salinization in the coastal plain, dichlorodiphenyltrichloroethane is currently in use in the watershed despite being a banned substance, the PAH contamination is directly linked to an old, disused railway track, and chromium and nickel are the two trace elements showing anthropogenic enrichment, being attributed to leather tanning and metal plating by small‐scale industries in the watershed.     

Spatial variations in nutrients and other physicochemical variables in the topographically closed Lake Baringo freshwater basin (Kenya)

Spatial physicochemical parameters were determined from 39 sampling sites distributed throughout Lake Baringo during December 2010. Mean values of temperature, dissolved oxygen concentration and electrical conductivity decreased successively with depth, while the pH remained constant. Only the turbidity values increased marginally with depth. Of the surface water parameters, mean (range) values of dissolved oxygen (DO), pH, electrical conductivity, water transparency and turbidity were 6.9 (4.5–8.4) mg L^?1, 8.3 (7.8–8.5), 573 (556–601)μS cm^?1, 33 (28–37) cm and 43.3 (32.7–54.6) NTU, respectively. Mean and range values of total nitrogen (TN), nitrate‐nitrogen(NO₃‐N), ammonia nitrogen (NH₄‐N), total phosphorus (TP) and soluble reactive phosphorus (SRP) were 788.4 (278–4486) μg L^?1, 4.5 (2.4–10.0) μg L^?1, 42.6 (33.8–56.3) μg L^?1, 102.9 (20.3–585.3) μg L^?1 and 23.5 (15.2–30.5) μg L^?1, respectively. Dissolved silica concentrations ranged from 19.7 to 32.7 mg L^?1, with a mean value of 24.7 mg L^?1. The chlorophyll‐a concentrations were quite low, ranging from 1.4 to 4.9 μg L^?1, with a mean value of 4.2 μg L^?1. In contrast to previous reported values, a key finding in the present study is a relatively high water transparency, indicating a relatively clear water column, due possibly to the fact that the sampling was conducted during the dry period. The nutrient levels remained low, and the chlorophyll‐a concentration also was an almost all time low value. A TP value of 20 μg L^?1 and higher confirms strongly eutrophic conditions prevailing in the lake, with an extremely low potential for fish production and low species diversity, consistent with other studies. The results of the present study, therefore, reinforce the database for future management and monitoring plans for the Lake Baringo ecosystem, which lies adjacent to known geothermally active zones and a saline Lake Bogoria.     

Episodic nearshore-offshore exchanges of hypoxic waters along the north shore of Lake Erie

We investigate the nearshore-offshore exchange of hypoxic waters during episodic coastal upwelling events in the nearshore waters of northern Lake Erie using intensive field observations and a validated hydrodynamic and water quality model. We observe wind-induced coastal upwelling events to be the dominant nearshore physical process in the lake which are energized every 5–10 days. When the winds were predominantly blowing from the west or south-west, epilimnetic waters were transported to the offshore bringing in hypolimnetic waters with low temperature (8–10 °C), dissolved oxygen (DO: 0–6 mg L^?1) and pH (6–7) to the nearshore zones. During these events, vertical diffusivity coefficients decreased from 10^?2 m² s^?1 to values as low as ~ 10^?7 m² s^?1. In late summer, the coastal upwelling events in the nearshore waters lower the near bottom DO to hypoxic levels (DO < 2 mg L^?1). Lake-wide observations of DO and pH show that they are positively and linearly correlated while in the nearshore DO and pH experience spatial and temporal variability where upwelling events were developed, which were further assessed using a three-dimensional model. The model accuracy to reproduce offshore hypoxia was first assessed on a lake-wide basis using a coarse resolution model for a five-year period (2008–2012) and in nearshore waters using a higher resolution model for 2013. We use the model results to delineate the near bottom areas experiencing hypoxia at time scales longer than 48 h.     

Hydrology of the Jordan River Basin: Watershed Delineation, Precipitation and Evapotranspiration

The Jordan River Basin is shared between Lebanon, Syria, Israel, Jordan and Palestine; the waters of the River are a critical resource for the future water security of the co-riparians. Because of the political situation in the region, field data such as rainfall and evapotranspiration are very difficult to obtain making the use of remote sensing and Geographic Information System (GIS) very useful to study water availability in the basin. The approach used in this paper integrates recently compiled data derived from satellite imagery (evapotranspiration, rainfall, and digital elevation model) into a GIS geodatabase to measure the contribution of each riparian country to the total available water in the basin.     

Land‐use effects on water quality of a first‐order stream in the Ozark Highlands,mid‐southern United States

Urban and agricultural land uses can alter the natural hydrologic conditions of streams and rivers and often degrade water quality. In the Ozark Highlands of the mid‐southern United States, the climate, topography, soil properties, karst limestone geology, agricultural practices and rapid urbanization make water quality of particular concern due to the increased potential for water quality degradation by contaminant leaching to groundwater and runoff to surface waters. The objective of this study was to evaluate the effects of season (i.e. dry/cool and wet/warm) and riparian land use (i.e. urban, grazed pasture, ungrazed pasture, wetland, cultivated agriculture and grassland) on surface water quality in a first‐order stream within a diverse agricultural watershed in the Ozark Highlands. Water samples were collected twice a month within each land use during base‐flow conditions from October 2006 through October 2007. Samples were also collected periodically during storm‐flow conditions from October 2006 through December 2007. The greatest in‐stream pH was adjacent to the grazed pasture. In‐stream NO₃‐N concentrations were greatest adjacent to the cultivated agriculture and grassland during the dry/cool season (i.e. October 2006 to March 2007) and averaged 2.67 mg L^?1. In‐stream soluble reactive P (SRP) concentrations were greatest adjacent to the grassland during the wet/warm season (i.e. April 2007 to October 2007) and averaged 0.81 mg L^?1. Concentrations of SRP, K, Mg and Zn were greater during storm‐ than base‐flow conditions and in‐stream As concentrations frequently exceeded 0.01 mg L^?1. Discharge and in‐stream NH₄‐N concentrations were unaffected by land use or season and averaged 0.003 m³ s^?1 and 0.10 mg L^?1, respectively, across all land uses and seasons. Results of this study clearly demonstrate the significant effect of adjacent land use on in‐stream water quality of a first‐order stream in a diverse agricultural watershed and highlight the importance of managing upstream land use in order to regulate downstream water quality. Copyright © 2010 John Wiley & Sons, Ltd.     

A Decision Tool for Allocating the Waters of the Jordan River Basin between all Riparian Parties

Shared water resources are strong sources of conflict in the Jordan River basin shared by Israel, Jordan, Palestine, Syria and Lebanon. The control and allocation of water has been explicitly made a part of the ongoing peace negotiations. This article calls for the application of international water law in the resolution of water disputes in the negotiating process. The challenging task for negotiators is to translate water law principles into operating rules and procedures for the equitable apportionment of waters from shared water resources. The negotiators need a decision tool based upon objective criteria or standards to reach equitable entitlements to shared water resources by all parties. This paper introduces a multi-criteria decision tool as a possible approach to the problem of allocating the waters of the Jordan River between all riparian parties. The prime principle of the criteria is equitable allocation factors identified by water law. A general mathematical model was derived in which the proportional entitlements of the Jordan River basin waters were determined to the five riparians. It is hoped that, waternegotiators review this approach.     

Anthropogenic and climatic influences over the past three centuries on characteristics of an Adirondack lake,Eastern North America

Fourth Lake is a drainage lake at 43°N, 74°W, from which a 37‐cm long mud‐water interface core was recovered. ²¹⁰Pb dating indicates the core spans ≈340 years, from the Little Ice Age through modern global warming. Diatom accumulation responds to anthropogenic watershed disturbances, declining slightly up‐core until a peak in the late‐1800s attributable to sediment and nutrient influx from logging and enlargement of the outlet dam. A dramatic decrease occurs ≈1900 as logging and lake filling ceased, and a smaller peak ≈1960 accompanies residential development. Similar changes occur in organic carbon accumulation, which ranges from 0.0038–0.024 mg cm^?2 year^?1, with generally decreasing values up‐core, punctuated by maximum values in the late‐1800s. Expressing diatoms as concentration, however, reveals a doubling up‐core that positively correlates with changes extending beyond the watershed, including Northern Hemisphere temperature, atmospheric CO₂ concentration and solar irradiance (R = 0.627, 0.675 and 0.400, respectively). A >50% increase in % organic carbon, from 3.8% to 5.9%, also positively correlates with these larger‐scale environmental conditions (R = 0.828, 0.830 and 0.832), while negative correlations with the extrabasinal records are exhibited by magnetic susceptibility (R = ?0.654, ?0.496, and ?0.660) and clay (R = ?0.770, ?0.762, and ?0.737). These changes are consistent with decreased sediment influx and reduced dilution of biogenous sedimentary components. In contrast to total diatoms, the accumulation of planktonic genus Asterionella displays a long‐term increase up‐core. Potential explanations include increasing duration of the ice‐free season or a shift in the timing of the spring bloom and a mismatch with abundance of predator(s). Asterionella also increases as a percentage of total diatoms, being positively correlated with extrabasinal conditions (R = 0.827, 0.774 and 0.674). This change occurs at the expense of many benthic genera and, over the past century, at the expense of tychoplanktonic genus, Aulacosiera. Heavily silicified, Aulacosiera requires strong mixing to remain within the epilimnion. Thus, its decline might result from increasing stratification caused by warming.     

Sediment greenhouse gases (methane and carbon dioxide) in the Lobo-Broa Reservoir, São Paulo State, Brazil: Concentrations and diffuse emission fluxes for carbon budget considerations

Carbon gases (methane, CH₄, and carbon dioxide, CO₂) were measured for the first time in sediments of the Lobo‐Broa Reservoir, near São Carlos in São Paulo State, Brazil. It is believed these are the first measurements of this kind in any of the many reservoirs located in Brazil. Even though the Lobo‐Broa Reservoir is classified as oligotrophic, the sediment gas concentrations were exceedingly high, ranging from 0.4–3 mmol L^?1 for CH₄ and 1–9 mmol L^?1 for CO₂. Both gases exceeded their in situ gas saturation values at these shallow water depths (7 m in central basin; 11 m at dam), resulting in numerous sediment bubbles. Organic matter was highly concentrated in the reservoir sediments, averaging 25.5% loss on ignition (LOI) (dam) to 26.9% LOI (central basin) for the 0–12 cm depth interval, with values as high as 29–30% LOI (12% organic carbon) in the surface 0–5 mm layer. The theoretical flux of dissolved pore water carbon gases to the sediment–water interface (SWI) averaged 3.4 mmol L^?1 m^?2 day^?1 CH₄ and 7.3 mmol L^?1 m^?2 day^?1 CO₂ for the surface 0–10 mm. From gas emission measurements at the water surface, it was calculated that 90% of CH₄ is consumed either at the SWI or in the water column, resulting in a loss of 0.31 mmol L^?1 m^?2 day^?1 of CH₄ to the atmosphere. However, only 20% of the total CO₂ gas transported across the water–atmosphere interface (36.3 mmol L^?1 m^?2 day^?1, or 1600 mg CO₂ m^?2 day^?1) was produced in the sediments. The remaining 80% of CO₂ probably comes from other carbon sources. With CH₄ oxidation in the aerobic water column, close to 30% of the carbon gas flux to the atmosphere could be accounted for by gas production of CO₂ and CH₄ in the sediments and their diffuse transport to the water column.     

Restoration of small lakes through cooperative management: A suitable strategy for poverty‐laden areas in developing countries?

Lake Rupa is a small, subtropical, shallow lake with a surface area of 100 ha situated 600 m a.s.l. in Central Himalaya, Nepal. This degraded lake was studied between 2000 and 2006, with the goal of determining whether or not it could be restored by a community‐based cooperative of local people living in its catchment. Main threats to the lake, its aquatic life and its very existence include encroachment by excessive aquatic vegetation, sedimentation, and low in‐lake concentrations of dissolved oxygen (DO). Small lakes (≤ 500 ha) are relatively prone to the process of ‘succession and climax’, although they also can be of social, environmental and ecological importance. Thus, their disappearance could spark social chaos and disorder in areas already having to cope with other rapid environmental changes. This means that credible mechanisms for revitalizing or protecting small lakes are an important goal. Accordingly, a lake cooperative of 329 households living in close vicinity to Lake Rupa was formed in 2002, by prioritizing traditional fishers, women and other deprived community members with the goals of respecting the citizenry and equity. Following the cooperative's campaigns directed at weed removal and fish stocking, encroachment of vegetation on the lake margins was halted, its aquatic weeds became under control, and its fisheries improved. In addition to the cooperative's restoration activities, several water quality parameters, including water transparency and DO and chlorophyll‐a concentrations, were monitored on a monthly basis. The measured water transparency was inconsistent, exhibiting large variations between 2000 and 2003. Relatively low, but consistent, values, however, were measured after 2004. The results imply that the removal of weeds, and sufficient nutrients and solar radiation are subsequently available to the lake's phytoplankton communities. Supporting this notion is that the chlorophyll‐a concentration spiked to 205 µg L⁻¹ in November 2006, the water transparency became consistent, and the DO concentration increased to >3.8 mg L⁻¹ during the critical months (March–May) after 2004. These water quality indicators indicated improvement in the degraded Lake Rupa, suggesting that the establishment of cooperatives such as that highlighted in this study could be a powerful and sustainable mechanism for restoring degraded lakes in similar socioeconomic settings by maintaining equity, by connecting communities with their resources, and by facilitating integrity, equity, citizenry and social justice.