Water Sink Research Articles

PBA-loaded albite-base ceramic foam in application to adsorb harmful ions of Cd, Cs and As(V) in water

PurposeThe purpose of this paper is to provide an investigation on a new kind of adsorbent materials, namely, the Prussian blue analog (PBA)-loaded albite-base porous ceramic foam, which can effectively adsorb the heavy metal ion in the wastewater.Design/methodology/approachThe natural zeolite powder has been used as the primary raw material to make a sort of porous ceramic foam by impregnating polymer foam in slurry and then sintering. Adjusting the technological parameters could control the bulk density of the ceramic product, which could float on water with the bulk density less than 1 g/cm3 and also sink in water with the bulk density higher than 1 g/cm3. After desilicating the porous ceramic foam, an Al-Fe type PBA with a strong function of ion exchange was loaded on the ceramic surface by directly yielding.FindingsThe adsorption performance for harmful metal ions was greatly improved by combining together the high adsorption capability of the PB analog and the efficient high specific surface area of the porous ceramic foam.Originality/valueThis work presents a PBA-loaded albite-base porous ceramic foam that can effectively adsorb the harmful substance in water, and the adsorption efficiency for some typical harmful ions, i.e., Cd2+, Cs+ and As(V), was examined under different conditions of the experimental period, the pH value and the ion concentration in the tested solution.

Sweet cherry water relations and fruit production efficiency are affected by rootstock vigor

Rootstock vigor is well known to affect yield and productive performance in many fruit crops and the dwarfing trait is often the preferred choice for modern orchard systems thanks to its improved productivity and reduced canopy volume. This work investigates the different physiological responses induced by rootstock vigor on cherry, by comparing shoot and fruit growth, water relations, leaf gas exchanges as well as fruit vascular and transpiration in/outflows of “Black Star” trees grafted on semi-vigorous (CAB6 P) and on semi-dwarfing (Gisela™6) rootstocks. The daily patterns of stem (Ψstem), leaf (Ψleaf) and fruit (Ψfruit) water potential, leaf photosynthesis, stomatal conductance and transpiration, shoot and fruit growth, fruit phloem, xylem and transpiration flows were assessed both in pre- and post-veraison, while productivity and fruit quality were determined at harvest. At both stages, no significant differences were found on Ψleaf, photosynthesis, fruit daily growth rates as well as fruit vascular and transpiration flows, while trees on Gisela™6 showed lower shoot growth rates and lower Ψstem and Ψfruit than trees on CAB6 P. The resulting decrease in stem-to-leaf Ψ gradient on Gisela™6 trees determined a reduction in shoot growth by decreasing shoot strength as sinks for water and carbohydrates. On the other hand, Gisela™6 fruit lowered their Ψfruit thanks to a higher osmotic accumulation and increased their competitiveness towards shoots, as confirmed by the higher productivity and fruit soluble solid content found at harvest for these trees. These results indicate that rootstock vigor alters resource competition between vegetative and reproductive growth, which can affect water use efficiency, yield, and fruit quality.

A wetland ecosystem service assessment tool; Development and application in a tropical peatland in Uganda

We present the methodological development of a surveying and accounting tool created in response to a lack of appropriate data for modelling ecosystem services in tropical wetlands in East Africa. The survey provides a practical field methodology for quickly characterising the environmental, vegetation, soil and hydrological properties of a wetland using a nested sample site and sub-plot procedure. The accounting procedure provides simple calculations for combing these survey data with literature values to estimate ecosystem services provided by the wetland. The wetland ecosystem service assessment is based on per unit area estimates by land cover type, and scaled by areal extent of each land cover. The tool was tested and deployed in 60 locations within the Kashambya wetland complex, southwest Uganda. Results of the survey and accounting procedure are presented along with data on wetland soil, vegetation and hydrological properties. Our results, showing standard errors, demonstrate that while the Kashambya wetland has been extensively modified by anthropogenic influences, it remains a large store of water (7.0 ± 1.3 m3) and carbon (0.5 ± 0.04 M t). The wetland is a large source of water vapour (40 ± 180 k m3 y−1) and sink for carbon (3 ± 4 k t y−1). The high uncertainty of flux estimates demonstrate the need for further biophysical modelling based upon the data captured by the survey tool. The wetland provides food production services valued as US$ 1 ± 0.1 M y−1. Our results show that ecosystem services provided by wetlands change significantly under different land cover, but high heterogeneity of ecosystem service provision exists within land cover classes. Greater understanding of spatial dynamics is required to improve accuracy of wetland ecosystem service assessments, and to examine the implications of land management and climate change on wetland ecosystem services.

On the possible presence of oxygen in the upper sediment layer of the hydrogen sulfide zone in the Black Sea

In the northeastern Black Sea the search was performed for living eukaryotic organisms (micro- and meiobenthos) in hypoxic and anoxic conditions as well as measurement of O2 in the bottom water layer and in the upper layer of sediments. The results have shown the presence of a deep maximum abundance of zoobenthos in a depth range of 215–244 m. This aggregation of benthic fauna occupies a layer of 30 m along the vertical. In general, the proportion of active meiobenthos was no greater than 1.5% of the total number of organisms recorded from the sample.The presence of aerobic benthos near the upper boundary of the H2S zone can be explained by: sliding down of sediments from a higher depth; quasi-periodic O2 supply due to fluctuations in the position of the isopycna and/or sinking of waters downslope in the bottom Ekman layer. Also, in the case of physical entry of oxygen into the bottom layer, it can remain for a relatively long time in the upper part of the H2S zone due to the lack of deep Mn+2 flux and reaction with it.

Water Sink Model for Robot Motion Planning.

There are various motion planning techniques for robots or agents, such as bug algorithm, visibility graph, Voronoi diagram, cell decomposition, potential field, and other probabilistic algorithms. Each technique has its own advantages and drawbacks, depending on the number and shape of obstacles and performance criteria. Especially, a potential field has vector values for movement guidance to the goal, and the method can be used to make an instantaneous and smooth robot movement path without an additional controller. However, there may be some positions with zero force value, called local minima, where the robot or agent stops and cannot move any further. There are some solutions for local minima, such as random walk or backtracking, but these are not yet good enough to solve the local minima problem. In this paper, we propose a novel movement guidance method that is based on the water sink model to overcome the previous local minima problem of potential field methods. The concept of the water sink model is to mimic the water flow, where there is a sink or bathtub with a plughole and floating piece on the water. The plughole represents the goal position and the floating piece represents robot. In this model, when the plug is removed, water starts to drain out via the plughole and the robot can always reach the goal by the water flow. The water sink model simulator is implemented and a comparison of experimental results is done between the water sink model and potential field.

The Manchester Observer

The newly digitised Manchester Observer (1818–22) was England’s leading radical newspaper at the time of the Peterloo meeting of August 1819, in which it played a central role. For a time it enjoyed the highest circulation of any provincial newspaper, holding a position comparable to that of the Chartist Northern Star twenty years later and pioneering dual publication in Manchester and London. Its columns provide insights into Manchester’s notoriously secretive local government and policing and into the labour and radical movements of its turbulent times. Rich materials in the Home Office papers in the National Archives reveal much about the relationship between radicals in London and in the provinces, and show how local magistrates conspired with government to hound the radical press in the north as prosecutions in London ran into trouble. This article also sheds new light on the founding of the Manchester Guardian, which endured as the Observer’s successor more by avoiding its disasters than by following its example. Despite the imprisonment of four of its main editors and proprietors the Manchester Observer battled on for five years before sinking in calmer water for lack of news.

Channelizing Streams for Agricultural Drainage Impairs their Nutrient Removal Capacity.

In agricultural basins, fluvial ecosystems can work as filters when retaining the nutrient excess from agricultural activities, mitigating the impacts downstream. In frequently flooded areas, like the Pampas Region of Argentina, natural streams are being channelized to reduce flood frequency and intensity, thus increasing land suitability for crop production, but the impact of these interventions on nutrient removal capacity by streams is unknown. To evaluate the effects of channelizing streams on the assimilation rate of nitrate, ammonia, and phosphorus, nutrient addition experiments were performed in streams of the southern Pampas under three different conditions: (i) channelized reaches without (C.A. Mey.) Palla (reeds), (ii) unchannelized reaches without reeds, and (iii) unchannelized reaches with reeds. Assimilation rates were estimated by applying the one-dimensional transport with inflow and storage (OTIS) model, which considers the solute transport with lateral flow and storage. Nitrate and ammonia uptake rates were higher in unchannelized than in channelized stream reaches, and a higher nitrate assimilation rate was found in the presence of reeds, indicating an important role of this macrophyte in the nitrate uptake. In the case of phosphorous, uptake rates were higher in unchannelized reaches with reeds than in the channelized reaches. These results suggest that channelizing first-order streams in agricultural landscapes of the Argentine Pampas may significantly reduce the ability of streams to mitigate nutrients loss to continental and marine water sinks.

Numerical analysis of the heat transfer and fluid flow characteristics of a nanofluid-cooled micropin-fin heat sink using the Eulerian-Lagrangian approach

In the present study, the thermofluid characteristics of a water and nanofluid-cooled micropin-fin heat sink have been evaluated by implementing a two-phase Eulerian-Lagrangian model. The nanofluid consisted of an aqueous suspension of the spherical-shaped alumina nanoparticles with the particle volume fraction (φ) ranging from 0.25% to 1%. The analysis has been performed by considering a heat sink comprising the staggered arrangement of 72 micropin-fins of the circular cross-section without tip clearance. A constant heat flux of 300 kW/m2 was subjected at the base of the heat sink, whilst the utilised pressure drop (∆P) across the heat sink was limited to ∆P<3000Pa. Heat transfer and fluid flow parameters were evaluated in terms of the local heat transfer coefficient, the enhancement ratio of the average convective heat transfer coefficient, thermal resistance and volume flow rate through the heat sink. Additionally, the temperature contours and flow streamlines across the heat sink elaborated the temperature distribution and flow attributes. Results indicated that under identical ∆P conditions, replacing water coolants with nanofluids optimised the thermal performance of the heat sink with a perceptible margin at the higher particle loadings. At the optimal pressure drop and particle concentration, nanoparticle dispersion into the hosting fluid demonstrated a maximum of 16% enhancement in the average heat transfer coefficient.

Assessing moisture sources of precipitation in the Western Pamir Mountains (Tajikistan, Central Asia) using deuterium excess

Air moisture of oceanic origin can be subject to long-range transport and could contribute to precipitation at distant places. With ongoing climate change the relationship between water vapour sources and sinks is under constant evolution and plays an important role for water budget assessments. This study analysed monthly integrated and event-based precipitation samples from two field sites in the Western Pamir Mountains (Tajikistan) for stable isotope compositions of oxygen (δ18O) and hydrogen (δ2H) of water. The aim was to investigate water vapour sources and, in particular, to evaluate contributions of water vapour from the Mediterranean region. The latter has been often postulated as a potential moisture source region for Central Asia. Deuterium excess values (d), that serve as a fingerprint of moisture origin, were below 13‰ in monthly integrated samples, for most of the year. This indicates a smaller contribution of high Mediterranean moisture (∼20‰) to the Western Pamir Mountains than originally expected. A maximum d value of 19‰ was observed in March, which is not in agreement with the common observation of increased Mediterranean contribution during winter (DJF). A Lagrangian backward trajectory model (HYSPLIT) was applied to infer the general air mass origin for sampled precipitation events. A maximum contribution of ‘western’ moisture of 40% was also detected in March, while 40%–60% of moisture that contributed to precipitation events in winter was transported by trajectories that originated from the Northern Indian Ocean.

On the Possible Presence of Oxygen in the Upper Sediment Layer of the Hydrogen Sulfide Zone in the Black Sea

In the northeastern Black Sea the search was performed for living eukaryotic organisms (micro- and meiobenthos) in hypoxic and anoxic conditions as well as measurement of O2 in the bottom water layer and in the upper layer of sediments. The results have shown the presence of a deep maximum abundance of zoobenthos in a depth range of 215–244 m. This aggregation of benthic fauna occupies a layer of 30 m along the vertical. In general, the proportion of active meiobenthos was no greater than 1.5% of the total number of organisms recorded from the sample.The presence of aerobic benthos near the upper boundary of the H2S zone can be explained by: sliding down of sediments from a higher depth; quasi-periodic O2 supply due to fluctuations in the position of the isopycna and/or sinking of waters downslope in the bottom Ekman layer. Also, in the case of physical entry of oxygen into the bottom layer, it can remain for a relatively long time in the upper part of the H2S zone due to the lack of deep Mn+2 flux and reaction with it.

A Time Series of Water Column Distributions and Sinking Particle Flux of Pseudo-Nitzschia and Domoic Acid in the Santa Barbara Basin, California.

Water column bulk Pseudo-nitzschia abundance and the dissolved and particulate domoic acid (DA) concentrations were measured in the Santa Barbara Basin (SBB), California from 2009–2013 and compared to bulk Pseudo-nitzschia cell abundance and DA concentrations and fluxes in sediment traps moored at 147 m and 509 m. Pseudo-nitzschia abundance throughout the study period was spatially and temporally heterogeneous (<200 cells L−1 to 3.8 × 106 cells L−1, avg. 2 × 105 ± 5 × 105 cells L−1) and did not correspond with upwelling conditions or the total DA (tDA) concentration, which was also spatially and temporally diverse (<1.3 ng L−1 to 2.2 × 105 ng L−1, avg. 7.8 × 103 ± 2.2 × 104 ng L−1). We hypothesize that the toxicity is likely driven in part by specific Pseudo-nitzschia species as well as bloom stage. Dissolved (dDA) and particulate (pDA) DA were significantly and positively correlated (p < 0.01) and both comprised major components of the total DA pool (pDA = 57 ± 35%, and dDA = 42 ± 35%) with substantial water column concentrations (>1000 cells L−1 and tDA = 200 ng L−1) measured as deep as 150 m. Our results highlight that dDA should not be ignored when examining bloom toxicity. Although water column abundance and pDA concentrations were poorly correlated with sediment trap Pseudo-nitzschia abundance and fluxes, DA toxicity is likely associated with senescent blooms that rapidly sink to the seafloor, adding another potential source of DA to benthic organisms.

EVALUASI RESERVOIR BATURAJA PADA LAPANGAN FALCON DENGAN MENGGUNAKAN SIMULASI RESERVOIR UNTUK MEMAKSIMALKAN PRODUKSI

Falcon Field begins with the discovery of the GG-1 wells are explored in August 1974. The program DST performed on one zone at Falcon Field in the Baturaja Formation producing 429 BOPD and 0.14 MMCFD. Then in 1978, Falcon Field was developed by constructing three wells on the platform GGA and in 1988 made eight more wells on the platform GGB. Falcon Field is the peak production in 1978 amounted to 5670 BOPD. Currently Falcon Field still in production of 1000 BOPD and 451 MCFPD of four wells. Cumulative production in January 2014 at 10.57 and 9.08 MMCF MMBO, and Recovery Factor is currently at 19.2%. Based on the structure map and well log correlation, Baturaja in Falcon Fields has anticline structure with orientation North-South fault. The thickness of zone has 1000 ft (~300 m) with oil column around 100 ft. To conduct field production performance predictions in the future, needs to be done the reservoir simulation modeling where the results are expected to represent the true reservoir model. Grid made in this model has a cell size of 50 mx 50 m with a thickness of 3 ft, 53 layers, and a total of about 650000 cell active cell. In the early, the validation of model is carried out for the initialization by using the Black Oil Simulator model. Initialization is intended to build initial equilibrium of the total hydrocarbon reservoir with the volume control of hydrocarbon static model calculations. The alignment stages of model or History Matching is done to see if the reservoir model that has been created to represent the actual condition of the reservoir. From the simulation reservoir the number of OOIP is 55.07 MMSTB, while OOIP with the static model is 55.2 MMSTB with a difference of 0.2 %. For the development of the Falcon Fields in the Reservoir Baturaja, the study wasperformed under planned five scenarios, namely the first scenario (base case), the second scenario (base case with the addition of rework moving field), the third scenario (Base case with wellwork and infill), the fourth scenario (Modeling Drawdown), and the fifth scenario (Modeling Downhole Water Sink). Scenario production started in January 2014 until January 2037 for 23 years with the aim to provide maximum drainage. Falcon Field production forecasting results for the first scenario, the second scenario, the third scenario, the fourth scenario, and scenarios fifth consecutive MMSTB of 12.87, 14.66 MMSTB, 15.3 MMSTB, MMSTB 14.01, 14.17 MMSTB with consecutive RF 23:37%, 26.62% , 27.78%, 25.44%, and 25.73%.

The role of microbially-mediated exopolymeric substances (EPS) in regulating Macondo oil transport in a mesocosm experiment

Large-scale exopolymeric substances (EPS) formation was observed in contaminated surface waters of the Gulf of Mexico, after the Deepwater Horizon oil spill. The conditions under which EPS are produced can cause variations in their physico-chemical properties, affecting the fate of the oil through either emulsification or coagulation with particles, followed by aggregation and marine oil snow (MOS) sedimentation. Here, we report results from a four-day mesocosm experiment that examined EPS production, the change in the bulk chemical composition (mainly polysaccharides and proteins), as well as the partitioning into different size fractions (suspended particulate matter (SPM), colloidal fraction, and sinking MOS). The treatments included 1) natural coastal seawater (Control), 2) a water accommodated fraction of oil (WAF), 3) a chemically-enhanced WAF with addition of oil dispersant Corexit (CEWAF), and 4) a diluted CEWAF (DCEWAF). Generally, the presence of WAF stimulated more extracellular polysaccharide production, whereas the addition of Corexit promoted more protein production. Moreover, marine aggregates changed from a terrestrial signature (higher aromaticity, lower EPS content and more uniform monosaccharide distribution) in the early stages of the experiment, to a fresher autochthonous signature (less aromatic, higher EPS content and glucose-dominated monosaccharide distribution) in the later stage of the mesocosm experiment. Corexit promoted the association between oil and proteins, assisting to emulsify the oil in colloids and SPM and delay the settling of EPS and oil (MOS) for the duration of the mesocosm. Furthermore, when oil, especially Corexit-dispersed oil, was present, extracellular polysaccharides were preferentially incorporated into sinking MOS relative to proteins, as evidenced from a lower protein-C/carbohydrate-C ratio of the sinking MOS than those of SPM and colloidal fraction in WAF, CEWAF and DCEWAF, respectively. This is in contrast to a higher protein-C/carbohydrate-C ratio in the sinking marine snow than those of SPM and colloidal fraction in the control. Likely, microbially-mediated extracellular polysaccharides are the key component that anchors the mineral ballast until the aggregates become dense enough and overcome the buoyancy added to the aggregates as a result of their association with oil/Corexit. We conclude that interactions between Corexit and EPS components regulate petroleum hydrocarbon distribution between the water column and sinking MOS.

The fate of Lake Baikal: how climate change may alter deep ventilation in the largest lake on Earth

Lake Baikal is the oldest, deepest, and most voluminous freshwater lake on Earth. Despite its enormous depth, episodically (almost twice a year) large amounts of surface, cold, and oxygenated water sink until the bottom of the lake due to thermobaric instability, with consequent effects on the ecology of the whole lake. A minimal one-dimensional model is used to investigate how changes in the main external forcing (i.e., wind and lake surface temperature) may affect this deep ventilation mechanism. The effect of climate change is evaluated considering the IPCC RCP8.5 and some idealized scenarios and is quantified by (i) estimating the mean annual downwelling volume and temperature and (ii) analyzing vertical temperature and dissolved oxygen profiles. The results suggest that the strongest impact is produced by alterations of wind forcing, while deep ventilation is resistant to rising lake surface temperature. In fact, the seasons when deep ventilation can occur can be shifted in time by lake warming, but not dramatically modified in their duration. Overall, the results show that Lake Baikal is sensible to climate change, to an extent that the ecosystem and water quality of this unique lacustrine system may undergo profound disturbances.

Quantification of water purification in South African palmiet wetlands.

Despite the importance of water purification to society, it is one of the more difficult wetland ecosystem services to quantify. It remains an issue in ecosystem service assessments where rapid estimates are needed, and poor-quality indicators are overused. We attempted to quantify the water purification service of South African palmiet wetlands (valley-bottom peatlands highly threatened by agriculture). First, we used an instantaneous catchment-scale mass balance sampling approach, which compared the fate of various water quality parameters over degraded and pristine sections of palmiet wetlands. We found that pristine palmiet wetlands acted as a sink for water, major cations, anions, dissolved silicon and nutrients, though there was relatively high variation in these trends. There are important limitations to this catchment-scale approach, including the fact that at this large scale there are multiple mechanisms (internal wetland processes as well as external inputs) at work that are impossible to untangle with limited data. Therefore, secondly, we performed a small field-scale field survey of a wetland fragment to corroborate the catchment-scale results. There was a reasonable level of agreement between the results of the two techniques. We conclude that it appears possible to estimate the water purification function of these valley-bottom wetlands using this catchment-scale approach.

Neodymium Evidence for Increased Circumpolar Deep Water Flow to the North Pacific During the Middle Miocene Climate Transition

AbstractLow salinity surface water inhibits local deepwater formation in the modern North Pacific. Instead, southern‐sourced Circumpolar Deep Water (CDW) fills the basin, which is the product of water masses formed from cold sinking centers in the Southern Ocean and North Atlantic. This CDW is responsible for transporting a significant amount of global heat and dissolved carbon in the deep Pacific Ocean. The history of its flow and the broader overturning circulation are widely assumed to be sensitive to climate perturbations. However, insufficient records exist of CDW presence in the deep North Pacific with which to evaluate its evolution and role in major climate transitions of the past 23 Ma. Here we report sedimentary coatings and fish teeth neodymium isotope values—tracers for water‐mass mixing—from deepwater International Ocean Discovery Program Site U1438 (4.7 km water depth) in the Philippine Sea, northwest Pacific Ocean. Our results indicate the water mass shifted from a North Pacific source in the early Miocene to a southern source by ~14 Ma. Within the age model and temporal constraints, this major reorganization of North Pacific water mass structure may have coincided with ice sheet build up on Antarctica and is most consistent with an increased northward flux of CDW due to enhanced sinking of cold water forced by Antarctic cooling. The northward extent of this flux may have remained relatively constant during much of the past 14 Ma.

The palaeopsychrosphere in the Devonian

The interpretation of Palaeozoic marine benthonic ostracods of the Thuringian Ecotype or as indicative of a palaeopsychrosphere has been controversial. We review the evidence and conclude that the characteristics and distribution of these ostracods are consistent with the existence of deep, cold, well-oxygenated water masses, formed by high-latitude sinking of surface waters, in the Devonian oceans, comparable with those of the modern ocean that constitute the psychrosphere (waters below the thermocline with temperature < 10 °C). We present a new palaeoceanographic model for the Frasnian-Famennian (Late Devonian) Kellwasser events that resulted in the extinction of 75% of marine ostracod taxa, mostly neritic or pelagic forms, while the deep-water Thuringian Mega-assemblage was relatively unaffected. We offer an explanation for the unlikely preservation of examples of such a deep-water (bathyal to abyssal) ostracod fauna that involves upwelling of deep cold waters on continental margins. * Speaker

Partitioning water source and sinking process of a groundwater-dependent desert plant community

Desert plant community is often structured in two distinct layers of woody and herbaceous plants. Partitioning its water source and sinking process remains a key uncertainty in this water-limited ecosystem. Our aims are to partition the evapotranspiration (ET) components into water loss from bare soil, shrub, and herbaceous plants; estimate the contributions of groundwater to ET and shrub layer transpiration (Tshrub); and determine the major drivers of ET components in a groundwater-dependent desert plant community in Central Asia. Eddy covariance, static chambers, and micro-lysimeters were used to measure ET and its components (transpiration and evaporation). Oxygen stable isotope and IsoSource model were used to determine the water source of dominant shrubs (Haloxylon ammodendron). The seasonal pattern of transpiration (T) for the herbaceous layer (Therb) differed markedly from that for Tshrub. Therb reached the maximum values at the beginning of the growing season, and then decreased to nearly zero at the middle and end of the growing seasons. Conversely, Tshurb were able to maintain throughout the growing season due to the deep root access to groundwater. In total, Tshrub, Therb, and evaporation (E) were 70, 16, and 82 mm year−1, they account for 42, 9, and 49% of total ET during 2014. Most of the groundwater was consumed by Tshrub (51 mm year−1), accounted for 73% of Tshrub. The contribution of groundwater to ET was 60 mm year−1, representing more than 35% of total ET during 2014. The seasonal dynamics of Tshrub, Therb, and E were shaped by different drivers: Tshrub: air temperature; Therb: soil water content and herbaceous plant cover; E: net radiation and precipitation. This study demonstrated that a better understanding of the source and sinking process of ET is crucial for predicting hydrological response under ongoing and projected climatic change scenarios in a groundwater-dependent desert plant community.

Addressing plastic in oceans

A traveling, international exhibition, Ocean Plastics Lab (above), is on the National Mall in Washington, D.C., through June 17 to highlight the role of science in understanding and combating plastics in the world’s oceans. Nick Rome (right) of the Consortium for Ocean Leadership, a group of academic and industry organizations, demonstrates that polypropylene—the blue pieces suspended in the tube—float in water, while polystyrene (red) and polyethylene terephthalate (white) sink. The exhibition is an initiative of the German Federal Ministry of Education & Research and the German Marine Research Consortium and is supported by the European Commission.

Geomechanical and hydrogeological characteristics of Quaternary in karst

AbstractKarst is a terrain with special hydrogeology and relief forms, and it develops in rocks that are relatively soluble in water. Quaternary deposits in karst areas of the Dinarides occupy relatively smaller areas, in poljes and beds of a small number of karst rivers. The subject of the study is the Quaternary formations in the Trebižat riverbed. Although the river has carved its bed through Quaternary limestones, occurrences of major water losses or sinking are not registered due to relatively thick, fine‐grained and clayey alluvium that has been deposited in the canyon. Their depth is relatively large and in places it is over 20 m. Tufa in the form fragments of different sizes is very often present. It has a high holey porosity that is partly due to the decomposition of water plant tissues, and partly due to the dissolution or releasing of organic tissue. Despite the high porosity, tufa does not have a high permeability because the pores are not well interconnected and are often filled with fine‐grained particles. The subject of the paper is geomechanical and hydrogeological properties of these sediments.