Arid Coastal Environments Research Articles

Solar-enhanced freshwater generation in arid coastal environments: A double basin stepped solar still with vertical wick assistance study in northern Gujarat

Harnessing solar energy for water distillation is a significant method for obtaining freshwater from saline and seawater, especially in remote areas. The primary objective of this research is to assess the performance of a novel double basin stepped-type solar still combined with the vertical wick-assisted unit in the northern part of Gujarat. Experiments were conducted during non-summer months at Central Salt and Marine Chemical Research Institute, (Location −21°45′32″N 72°8′39″E). The set-up was designed, fabricated, and investigated for freshwater production, efficiency analysis, and exergy analysis. Accordingly, in-depth thermal analysis was carried out for the entire unit in terms of predicted water generation and efficiency of the system. The maximum potable water production as 5.2 kg/m2 and 1.9 kg/m2 was attain from double basin stepped solar still and vertical wick unit respectively followed by cumulative overnight productivity of 1 kg/m2. This being said that the average freshwater production from the system is realized to be 8 kg/m2 day which was a significant output in the domain of solar still. Furthermore, 48 % and 26 % maximum thermal efficiencies were pursued for the double basin set-up and wick-assisted set-up respectively. Accordingly, 30 % and 21 % average exergy efficiency for double basin and vertical wick units respectively. The customer end cost for one litre of fresh water from the designed set-up is 0.0048$/L, this effective evidence is built-up to suggest an efficient and superior option to implement this kind of set-up near coastal and salt farming regions where scarcity of potable water is observed.

Arid Coastal Carbonates and the Phanerozoic Record of Carbonate Chemistry

AbstractOcean chemistry and carbonate sedimentation link Earth's climate, carbon cycle, and marine pH. The carbonate system in seawater is complex and there are large uncertainties in key parameters in deep time. Here, we link sedimentary textures formed in arid coastal environments and preserved in the rock record to past seawater carbonate chemistry. Prior to the mid‐Mesozoic, tepee structures and pisoids – features associated with peritidal environments – co‐vary with available shelf area during cycles of supercontinent formation and rifting. In contrast, tepees and pisoids are consistently scarce after the mid‐Mesozoic, which coincides with a radiation in pelagic calcifiers as well as the breakup of Pangea. Numerical models suggest that the global and temporal abundances of tepee structures and pisoids are correlated with secular shifts in seawater chemistry, and that trends likely reflect the underlying influence of tectonics and biotic innovation on marine alkalinity and the saturation states of carbonate minerals. As independent sedimentary proxies, tepees and pisoids serve as benchmarks for global carbon cycle models and provide a new proxy record of seawater chemistry that can help discern links among tectonics, biotic innovation, and seawater chemistry.

A geographic expression of the sepiolite-palygorskite continuum in soils of northwest South Africa

Some coastal soils in Namaqualand have significant amounts of sepiolite. Palygorskite is relatively low in coastal soils but it is abundant at some inland sites up to 600 km from the coast. This distribution is explained by examining relationships of major ionic species in saturated paste extracts. Our study found two categories of geographically and chemically distinct palygorskite-containing soils: 1) high Mg, palygorskite soils 130 km inland with similar Mg levels to coastal sepiolitic soils, and 2) low Mg, palygorskite soils 600 km inland. The geographic progression from high-Mg sepiolite-containing soils at the coast, through high-Mg palygorskite soils to low-Mg palygorskite soils farthest from the coast parallels the chemical variation in the sepiolite-palygorskite continuum from sepiolite, the most magnesic endmember at the coast, to palygorskite the least magnesic endmember farthest inland. MgSO40 and MgCl+ ion complexes do not appear to depress Mg2+ activity to an extent that is able to distinguish sepiolite-containing from palygorskite-containing soils. Calcite in the profile is strongly associated with occurrence of fibrous clay minerals, and dolomite is absent. Compositions of soil saturated paste extracts conform to their respective mineral stability fields, contrasting with previous work in the area. The previous interpretation, therefore, that fibrous minerals may currently be in a state of alteration requires revision. Evaporation of soil pore waters in the marine-influenced region results in increased Mg and Ca and decreased pH, even with precipitation of sepiolite and calcite. These chemical changes with evaporation are important for understanding the evolution of soil solutions and precipitating minerals in arid coastal environments and the chemistry of waterbodies associated with them.

Food for honeybees? Pollinators and seed set of Anthyllis barba-jovis L. (Fabaceae) in arid coastal areas of the Mediterranean basin.

Abundance and diversity of insect pollinators are declining in many ecosystems worldwide. The abundance and diversity of wild and managed bees are related to the availability of continuous floral resources. In particular, in Mediterranean basin countries, the presence of wildflower spots enhances the establishment of social Apoidea, since coastal regions are usually characterized by pollen and nectar shortage in early spring and late summer. Anthyllis barba-jovis produces both nectar and pollen as important food source for bees helping them to overcome early spring period food shortage. We investigated flowering, seed set, and pollinator diversity of A. barba-jovis in arid coastal environments of the Mediterranean basin. Pollinator abundance reached a maximum in early April. Honeybees were the most common pollinators followed by bumblebees and solitary bees. Plants prevented from entomophilous pollination showed inbreeding depression with a strong decrease in seed-set. To the best of our knowledge, this is the first report on pollination ecology of A. barba-jovis.

Modeling Soil Salinity in Greenhouse Cultivations Under a Changing Climate With SALTMED

Soil salinity is a major soil degradation threat especially for arid coastal environments where it hinders agricultural production, thus imposing a desertification risk. In the prospect of a changing climate, soil salinity caused by brackish water irrigation introduces additional uncertainties regarding the viability of deficit irrigation and intensive cultivation practices such as greenhouse cropping. Here, we propose a modification of the SALTMED leaching requirement model to account for greenhouse cultivation conditions. The model is applied in the RECARE Project Case Study of Timpaki, a semiarid region in south-central Crete, Greece, where greenhouse horticulture is an important land use. Excessive groundwater abstractions toward irrigation have resulted in a drop of the groundwater level in the coastal part of the aquifer, thus leading to seawater intrusion and in turn to soil salinization. Crop yield and soil profile electrical conductivity (EC) sensitivity to initial soil EC (up to 2 dS m−1) and irrigation water EC (up to 3 dS m−1) are modeled for the locally popular horticultural crops of Solanum lycopersicum, Solanum melongena, and Capsicum annuum. Climate model data obtained from nine general circulation models for the “worst case” representative concentration pathway of 8.5 W m−2 of the fifth phase of the Coupled Model Intercomparison Project are corrected for bias against historical observations with the Multisegment Statistical Bias Correction method and used to estimate crop yield and soil profile EC sensitivity in a warmer future. Results show that the effects of climate change on S. lycopersicum greenhouse cultivations of Timpaki will be detrimental, whereas S. melongena and C. annuum cultivations may show greater resilience.

A spatial pattern analysis of the halophytic species distribution in an arid coastal environment.

Obtaining information about the spatial distribution of desert plants is considered as a serious challenge for ecologists and environmental modeling due to the required intensive field work and infrastructures in harsh and remote arid environments. A new method was applied for assessing the spatial distribution of the halophytic species (HS) in an arid coastal environment. This method was based on the object-based image analysis for a high-resolution Google Earth satellite image. The integration of the image processing techniques and field work provided accurate information about the spatial distribution of HS. The extracted objects were based on assumptions that explained the plant-pixel relationship. Three different types of digital image processing techniques were implemented and validated to obtain an accurate HS spatial distribution. A total of 2703 individuals of the HS community were found in the case study, and approximately 82% were located above an elevation of 2 m. The micro-topography exhibited a significant negative relationship with pH and EC (r = -0.79 and -0.81, respectively, p < 0.001). The spatial structure was modeled using stochastic point processes, in particular a hybrid family of Gibbs processes. A new model is proposed that uses a hard-core structure at very short distances, together with a cluster structure in short-to-medium distances and a Poisson structure for larger distances. This model was found to fit the data perfectly well.

A multi-period mixed integer linear programming model for water and energy supply planning in Kuwait

The demand for water often necessitates desalination, particularly in arid coastal environments. Desalination is often integrated with electrical cogeneration. The demands for water and electricity change over time and are subject to uncertainty. A country-wide large-scale energy and water cogeneration planning model for Kuwait is formulated as a multi-period mixed integer linear programming problem and solved to minimize the net present value over the time period of 2013–2050. Five different plant technology options were considered for desalination and cogeneration including Oil & Multi Stage Flash, Natural Gas & Multi-Effect Distillation, Natural Gas & Reverse Osmosis, Solar Energy & Multi-Effect Distillation, and Solar Energy & Reverse Osmosis. Both water and energy usage in Kuwait and data from existing plants were utilized in providing the parameters and forecasts necessary for solution of the mathematical programming model. The model provides technology choice and associated capacity decisions for existing plants, new plants at green sites, and existing plant capacity expansions as well as their timing to meet the demands.

Erratum to: Natural and anthropogenic controls on sediment composition of an arid coastal environment: Sharm Obhur, Red Sea, Saudi Arabia

Erratum to: Natural and anthropogenic controls on sediment composition of an arid coastal environment: Sharm Obhur, Red Sea, Saudi Arabia

Natural and anthropogenic controls on sediment composition of an arid coastal environment: Sharm Obhur, Red Sea, Saudi Arabia

The present study investigated the natural and anthropogenic processes that control the composition of the bottom sediments of Sharm Obhur, Red Sea. Mineralogical analysis using XRD indicated that the sediments consist of carbonate and non-carbonate minerals. Elemental interrelationships allowed differentiating two groups of elements of different sources and origin. Elements that are in the same group are positively correlated, while they correlate negatively with elements of the other group. The first group includes silicon, Al, Fe, Mn, Mg, vanadium (V), chromium (Cr), Co, Ni, Cu, and Zn, whereas the other group includes Ca, Sr, and CaCO3. The highest concentration levels of the first group and the highest content of non-carbonate minerals were obtained from the sediments near the head of the sharm (zone A), whereas the sediments near the mouth of the sharm (zone B) yielded high concentrations of second group and carbonate minerals. Metal enrichment and contamination factors and pollution load index were calculated. The values of these indices differentiate two groups of metals: lithogenic and non-lithogenic. Except for lead (Pb) at one sampling site, metals in zone A sediments are of lithogenic source, supplied to the sharm either naturally by aeolian transportation and through Wadi Al-Kuraa'a during rare but major floods or by human activities such as dumping and shore protection. Non-lithogenic Cr, Pb, V, and Mn were documented from some sampling sites in zone B, and their occurrences are related to waste disposal and fossil fuel combustion.

Are mangroves in arid environments isolated systems? Life-history and evidence of dietary contribution from inwelling in a mangrove-resident shrimp species

The Arabian Gulf represents one of the more northerly extremes of mangrove distribution in the Indo-Pacific, and is populated only by Avicennia marina, due to its tolerance of high salinity and wide temperature extremes. Recent studies suggest that in the arid coastal environment of the western Arabian Gulf, export of carbon and nitrogen from mangroves to adjacent habitats may be limited, though it is not clear if this is due to low productivity or physical factors such as the lack of freshwater flow and the tidal regime. Although seagrass and macroalgal habitats are relatively much more dominant by area, with only small pockets of mangrove around the edges of embayments, it is not evident if inwelling from these habitats support mangrove fauna. Year-round sampling in mangroves at Al-Khor, Qatar, indicates that Palaemon khori, an endemic shrimp species, is strongly associated with mangroves throughout its post-settlement life cycle, from recruitment as small 9–10 mm juveniles through to mating and egg production. Rapid post-recruitment growth (k = 1.8, L∞ = 42 mm for females, k = 1.5, L∞ = 35 mm for male) means that most individuals reached adult size in the first few months after settlement, with reproduction occurring in the following spring. As might be expected from year-round residence in the mangrove, dual 13C and 15N isotope analysis indicated a strong contribution of mangroves to shrimp tissue growth (Mean and 95% confidence range, 37% and 27–48%), but with a weaker significant contribution from particulate organic matter (20% and 1–37%), mangrove epiphytes (16% and 2–33%) and seagrasses (9% and 0.2–18%). Other primary producers contribute the remaining 18% to shrimp nutrition but the 95% confidence ranges include zero, suggesting possibly non-significant roles in supporting the shrimp population. This dietary information supports the view that fauna resident within arid mangrove systems are mainly dependent on localised retention and cycling of nutrients with a smaller contribution from inwelling.

Sustainable management of a coupled groundwater–agriculture hydrosystem using multi-criteria simulation based optimisation

In this paper we present a new simulation-based integrated water management tool for sustainable water resources management in arid coastal environments. This tool delivers optimised groundwater withdrawal scenarios considering saltwater intrusion as a result of agricultural and municipal water abstraction. It also yields a substantially improved water use efficiency of irrigated agriculture. To allow for a robust and fast operation we unified process modelling with artificial intelligence tools and evolutionary optimisation techniques. The aquifer behaviour is represented using an artificial neural network (ANN) which emulates a numerical density-dependent groundwater flow model. The impact of agriculture is represented by stochastic crop water production functions (SCWPF). Simulation-based optimisation techniques together with the SCWPF and ANN deliver optimal groundwater abstraction and cropping patterns. To address contradicting objectives, e.g. profit-oriented agriculture vs. sustainable abstraction scenarios, we performed multi-objective optimisations using a multi-criteria optimisation algorithm.

Assessing surficial foraminiferal distributions as an overwash indicator in Sur Lagoon, Sultanate of Oman

Abstract The identification of tsunami and storm deposits in arid coastal environments can be problematic, as overwash sediments may not show significant contrasting lithologic characters with lagoonal sediments. In this study foraminifera were evaluated as an overwash indicator in a small (12 km2) intertidal lagoon located at Sur, in the Sultanate of Oman. The lagoon is shallow (

Reestablishing a Keystone Species in an Arid Coastal Environment: Saltbush (Salsola nollothensis) in Namibia

Beach hummocks are important ecological components of coastal ecosystems. Although hummocks are naturally adapted to harsh conditions, reestablishing them in arid areas poses great challenges. During a collaborative project, researchers from Namdeb Diamond Corporation and the Millennium Seed Bank Partnership investigated practical methods to reestablish saltbush ( Salsola nollothensis ) beach hummocks to restore areas disturbed by alluvial diamond mining. With focus on simple methods that can be implemented over large areas, collecting seed-containing debris, placing windbreaks, and seeding these with debris are some of the means currently investigated. Preliminary findings indicate that seed quality may deteriorate quickly if seeds are stored in ambient conditions, and storage under controlled conditions and/or seed harvesting shortly before restoration is recommended. Laboratory tests indicate a naturally high proportion of empty seeds, possibly short seed longevity, and that seeds must not be buried too deeply for seedling emergence. Further, seasonal and site-related variation in seed production influences the quality and amount of viable seeds available. All this suggests a complex set of environmental conditions that have to be met to achieve natural recovery or restoration goals. This project illustrates the benefits of partnerships in restoration that made it possible to investigate practical field questions with scientific sophistication, making an international initiative relevant to applied restoration ecology in a developing country.

Pond treatment and effluent reuse of sewage from an oil production site in an arid coastal environment

A pond system consisting of two lines each of an anaerobic followed by facultative and maturation ponds is used to treat site sewage from oil and gas production operations in an arid coastal environment. The performance of the pond system was evaluated together with the suitability of treated effluent for reuse in local irrigation. Effluent from the pond system by-and-large satisfies criteria for irrigation of non-food crop plants with respect to chemical parameters. The primary problem is coliform bacteria levels which are an order of magnitude higher than preferred values. First-order decay rate constants for each pond were calculated from a mass balance model that assumes complete mixing and incorporates the considerable evaporation that occurs in this setting. While the anaerobic ponds of both lines exhibit suitable performance, rate calculations indicate that the facultative and maturation ponds of the East Line are performing better than the West. A tracer study of the facultative and maturation ponds indicates that some short-circuiting is occurring in the West Line. A field experiment of coliform transport in irrigated soil gives indications of short- and long-term risks associated with reuse of the effluent.

Inter- and intraspecific variation in the use of marine food resources by three Cinclodes (Furnariidae, Aves) species: carbon isotopes and osmoregulatory physiology

The avian genus Cinclodes (Furnariidae) includes species that inhabit both inland and marine shores. We compared the carbon isotopic composition and osmoregulatory capacities of field caught individuals of three Cinclodes species in Chile. Cinclodes nigrofumosus is a resident of coastal shores, whereas C. oustaleti and C. patagonicus inhabit both coastal and inland environments. The tissues of C. nigrofumosus exhibited distinctively marine delta(13)C values, whereas those of C. oustaleti and C. patagonicus were intermediate between marine and terrestrial values. The differences in carbon isotopic composition among these three species were paralleled by differences in osmoregulatory characteristics. The species that carbon isotopes revealed to be strictly marine, C. nigrofumosus, had relatively larger kidneys with a higher fraction of total renal tissue occupied by medullary cones than its congeners C. oustaleti and C. patagonicus. Cinclodes nigrofumosus individuals also produced more concentrated urine. In addition to interspecific differences in osmoregulation, we found intraspecific differences. Cinclodes nigrofumosus collected at an arid site with limited or no available fresh water exhibited larger kidneys and higher relative medullary thickness than individuals collected at a mesic site. Cinclodes nigrofumosus, like all passerines, lacks functional salt glands. This species appears to be unique among passerines in its ability to live in extreme arid coastal environments and to cope with a marine diet that imposes high osmotic loads.

Chemical, crystallographic and stable isotopic properties of alunite and jarosite from acid—Hypersaline Australian lakes

Chemical, crystallographic and isotopic analyses were made on samples containing alunite and jarosite from the sediments of four acid, hypersaline lakes in southeastern and southwestern Australia. The alunite and jarosite are K-rich with relatively low Na contents based on chemical analysis and determination of unit cell dimensions by powder X-ray diffraction. Correcting the chemical analyses of fine-grained mineral concentrates from Lake Tyrrell, Victoria, for the presence of halite, silica and poorly crystalline aluminosilicates, the following formulas indicate best estimates for solid-solution compositions: for alunite, K 0.87Na 0.04(H 3O) 0.09(Al 0.92Fe 0.08) 3(SO 4) 2(OH) 6 and for jarosite, K 0.89Na 0.07(H 3O) 0.04(Fe 0.80Al 0.20) 3(SO 4) 2(OH) 6. The δD-values of alunite are notably larger than those for jarosite from Lake Tyrrell and it appears that the minerals have closely approached hydrogen isotope equilibrium with the acidic regional groundwaters. The δD results are consistent with a fractionation ∼60–70‰ between alunite and jarosite observed in other areas. However, interpretation of δD results is complicated by large variability in fluid δD H 2O from evaporation, mixing and possible ion hydration effects in the brine. δD-values of water derived from jarosite by step-wise heating tend to be smaller at 250°C, at which temperature hydronium and other non-hydroxyl water is liberated, than at 550°C, where water is derived from the hydroxyl site, but the differences are not sufficiently different to invalidate measurements of total δD obtained by conventional, single-step heating methods. δ 34S-values for alunite and jarosite from the four lakes (+19.7 to +21.2‰ CDT) and for aqueous sulfate from Lake Tyrrell (+18.3 to +19.8‰) are close to the values for modern evaporites ( +21.5 ±0.3‰) and seawater ( +20±0.5‰) and are probably typical of seawater-derived aerosols in arid coastal environments. δ 34-S-values slightly smaller than that for seawater may reflect a minor contribution of sulfate from pyrite oxidation in the Parilla Sand or a reservoir effect from removal of gypsum enriched in 34S. δ 18O SO 4 -values for alunite from three Western Australia lakes (+17.8 to +18.3‰ V-SMOW), for alunite and jarosite from Lake Tyrrell (+22.6 to +24.9‰) and for aqueous sulfate from Lake Tyrrell (+17.3 to +19.0‰) are much larger than the average value for seawater (+9.6‰). The data suggest an approach to 18O- 16O equilibrium between aqueous sulfate and groundwater, which is known from experimental studies to be possible at low pH and low temperatures, but has not been previously documented in nature. A residence time of ∼0.1–1 kyr for sulfate in acidic water (pH 3–4) is needed to achieve the apparent partial oxygen exchange, using previously published data of R.M. Lloyd.

KIAWE: A TREE CROP IN HAWAII

SUMMARY The kiawe tree (Prosopis pallida) has been greatly valued in Hawaii, as a source of fodder for livestock and honeybees and for its timber and charcoal, since it was first introduced there in 1838. In recent years the rise of the tourist industry has considerably reduced the area of kiawe woodlands, amounting to 60 730 ha in 1961. The development of a multiple-use management programme for the remaining woodlands would be very attractive economically. Kiawe has potential for cultivation in arid coastal environments with saline soils and rainfall that may not exceed 254 mm per annum.