| 1. |
- de Wit, Heleen A., et al.
(author)
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Current Browning of Surface Waters Will Be Further Promoted by Wetter Climate
- 2016
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In: ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS. - : American Chemical Society (ACS). - 2328-8930. ; 3:12, s. 430-435
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Journal article (peer-reviewed)abstract
- Browning of surface waters because of increasing terrestrial dissolved organic carbon (OC) concentrations is a concern for drinking water providers and can impact land carbon storage. We show that positive trends in OC in 474 streams, lakes, and rivers in boreal and subarctic ecosystems in Norway, Sweden, and Finland between 1990 and 2013 are surprisingly constant across climatic gradients and catchment sizes (median, +1.4% year(-1); interquartile range, +0.8-2.0% year(-1)), implying that water bodies across the entire landscape are browning. The largest trends (median, +1.7% year(-1)) were found in regions impacted by strong reductions in sulfur deposition, while subarctic regions showed the least browning (median, +0.8% year(-1)). In dry regions, precipitation was a strong and positive driver of OC concentrations, declining in strength moving toward high rainfall sites. We estimate that a 10% increase in precipitation will increase mobilization of OC from soils to freshwaters by at least 30%, demonstrating the importance of climate wetting for the carbon cycle. We conclude that upon future increases in precipitation, current browning trends will continue across the entire aquatic continuum, requiring expensive adaptations in drinking water plants, increasing land to sea export of carbon, and impacting aquatic productivity and greenhouse gas emissions.
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| 2. |
- Haghighatafshar, Salar, et al.
(author)
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Laboratory-scale assessment of vacuum-degassed activated sludge for improved settling properties
- 2017
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In: Environmental Technology (United Kingdom). - : Informa UK Limited. - 1479-487X .- 0959-3330. ; 38:17, s. 2193-2201
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Journal article (peer-reviewed)abstract
- Vacuum degassing of activated sludge was tested at eight different Swedish wastewater treatment plants with laboratory-scale equipment in batch mode in order to evaluate its efficiency on improvement of sludge compaction and settling properties. The results show that the efficiency of the degassing technique is mainly dependent on the initial sludge volume index (SVI) of the target sludge which was found to be related to its process configuration. Facilities with full activated sludge-based nitrogen removal processes, including both nitrification and denitrification, had high SVIs (>300 mL g(-1)) and were strongly affected by vacuum degassing with reduction of SVI up to 30%. Nitrogen removal facilities also including biological phosphorus removal showed better compaction and settling properties with relatively lower SVIs and were affected to a lesser extent by degassing with SVI reduction of 10-20%. Wastewater treatment plants without full biological nitrogen removal, lacking either nitrification or denitrification (or both) processes in the activated sludge had the lowest SVIs observed with almost no effect of vacuum degassing.
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| 3. |
- Smith, Madison M., et al.
(author)
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Thin and transient meltwater layers and false bottoms in the Arctic sea ice pack—Recent insights on these historically overlooked features
- 2023
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In: Elementa: Science of the Anthropocene. - 2325-1026. ; 11:1
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Research review (peer-reviewed)abstract
- The rapid melt of snow and sea ice during the Arctic summer provides a significant source of low-salinity meltwater to the surface ocean on the local scale. The accumulation of this meltwater on, under, and around sea ice floes can result in relatively thin meltwater layers in the upper ocean. Due to the small-scale nature of these upper-ocean features, typically on the order of 1 m thick or less, they are rarely detected by standard methods, but are nevertheless pervasive and critically important in Arctic summer. Observations during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in summer 2020 focused on the evolution of such layers and made significant advancements in understanding their role in the coupled Arctic system. Here we provide a review of thin meltwater layers in the Arctic, with emphasis on the new findings from MOSAiC. Both prior and recent observational datasets indicate an intermittent yet longlasting (weeks to months) meltwater layer in the upper ocean on the order of 0.1 m to 1.0 m in thickness, with a large spatial range. The presence of meltwater layers impacts the physical system by reducing bottom ice melt and allowing new ice formation via false bottom growth. Collectively, the meltwater layer and false bottoms reduce atmosphere-ocean exchanges of momentum, energy, and material.The impacts on the coupled Arctic system are far-reaching, including acting as a barrier for nutrient and gas exchange and impacting ecosystem diversity and productivity.
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| 4. |
- Ali, Salahalddin, et al.
(author)
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GIS Based Soil Erosion Estimation Using EPM Method, Garmiyan Area, Kurdistan Region, Iraq
- 2016
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In: Journal of Civil Engineering and Architecture. - : David Publishing Company. - 1934-7359 .- 1934-7367. ; 10, s. 291-308
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Journal article (peer-reviewed)abstract
- Using empirical model is one of the approaches of evaluating sediment yield. This research is aimed at predicting erosion and sedimentation in Garmiyan area at Kurdistan Region, Iraq used EPM (erosion potential model) incorporating into GIS (geographic information system) software. This basin area is about 1,620 km2. It has a range of vegetation, slope, geological, soil texture and land use types. The spatial distribution of gully erosion shows three main zones in the studied area (slight to moderate gully, high gully and sever fluvial erosion). They form about 10%, 89% and 1% of gully erosion in the studied area respectively. The results of the EPM model show that the values of the coefficient of erosion Z are classified as moderate to high erosion intensity. They increase northward due to increasing of slope, elevation and rate of precipitation that generate Hortonian overland flow, which is due to high discharge and huge fluvial erosion power that cause ground surface erosion to produce large quantity of sediment. The results of GSP (spatial sediment rate) are increasing northward similar to Z due the same reasons, while the value of total sediment rate, shows different values for each watershed because they are mainly affected by the total watershed area.
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| 5. |
- Ali, Salahaldin S., et al.
(author)
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Evaluation of selected site location for subsurface dam construction within Isayi watershed using GIS and RS Garmiyan area, Kurdistan region
- 2014
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In: Journal of Water Resource and Protection. - : Scientific Research Publishing, Inc.. - 1945-3094 .- 1945-3108. ; 6:11, s. 972-987
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Journal article (peer-reviewed)abstract
- Garmiyan area suffers from many water problems such as poor rainfall rate, water shortage, aridity and absence of groundwater in many places. Hence the subsurface dam is the best solution due to many advantages such as; low cost of construction, least maintenance, low evaporation, no con-tamination, utilization of the land over the dam and better storage. The objective of this study is to evaluate the suitability of the selected site location for subsurface dam construction, to serve as strategic water supply storage, to solute the aridity and water shortage in this area of arid to semi arid climate in Isayi watershed within the stream deposits.Geographic information systems (GIS) and remote sensing through satellite images and Digital El-evation Model (DEM) interpretation and analysis have facilitated the investigation with more ac-curacy. ArcGIS helped in construction of thematic maps of the studied area.The geologic, structural, geomorphologic, hydrologic, hydrogeologic, characteristics with GPR survey show the suitability of the selected site location for construction of subsurface dam. According to the standard water quality for domestic, irrigation and livestock the water quality of all water samples are within the recommended range and the best time to be chosen, for construction of the subsurface dam, is during the autumn season from September to November.
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| 6. |
- Futter, Martyn, et al.
(author)
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Conceptualizing and communicating management effects on forest water quality
- 2016
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In: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 45, s. S188-S202
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Journal article (peer-reviewed)abstract
- We present a framework for evaluating and communicating effects of human activity on water quality in managed forests. The framework is based on the following processes: atmospheric deposition, weathering, accumulation, recirculation and flux. Impairments to water quality are characterized in terms of their extent, longevity and frequency. Impacts are communicated using a "traffic lights" metaphor for characterizing severity of water quality impairments arising from forestry and other anthropogenic pressures. The most serious impairments to water quality in managed boreal forests include (i) forestry activities causing excessive sediment mobilization and extirpation of aquatic species and (ii) other anthropogenic pressures caused by long-range transport of mercury and acidifying pollutants. The framework and tool presented here can help evaluate, summarize and communicate the most important issues in circumstances where land management and other anthropogenic pressures combine to impair water quality and may also assist in implementing the "polluter pays" principle.
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