The southern margin of the Arabian Gulf is a ''classic'' shallow-water, evaporative, carbonate-producing setting. The sediments and early diagenetic products creating the ''Great Pearl Bank'' of the United Arab Emirates to the east and accumulating in the coastal regions of Qatar to the west have long been studied as modern analogs for ancient evaporitic carbonate deposits of the rock record. An integrated study measuring the chemistry of Qatar subtidal coastal waters, evaporating tidal-pond waters (to halite saturation), and meteoric pond waters was undertaken encompassing both the dry (fall) and wet (winter/spring) seasons of 2016-2017. Measured parameters included temperature, pH, dissolved oxygen, and alkalinity, as well as major-ion (Na þ , Ca 2þ , Mg 2þ , K þ , Sr 2þ , Cl -, and SO 4 2-) and stable-isotope (d 18 O and dD) composition. Initial concentration by evaporation (to~90 practical salinity units (psu)) is interpreted to drive minor diagenetic aragonite precipitation. Further evaporation initially causes minor aragonite dissolution followed by gypsum and halite precipitation. One pond showed evidence of ongoing replacive dolomitization interpreted to be driven by H 2 S formation and oxidation in association with microbial breakdown of organic matter. The stable-isotope composition of water in restricted ponds is a function of the degree of evaporation and dilution by meteoric waters during the wet season. Unexpectedly, beyond 350 psu, d 18 O and dD continue to rise reaching values greater than 12 and 60%, respectively. The slope of the d 18 O-dD regression line exhibits no differences between dry and wet seasons.During collection of coastal waters (up to~90 psu), live Pirenella cingulata (previously Cerithidea cingulata) gastropods were collected and their shells analyzed for d 18 O and d 13 C, as well as Sr 2þ and Ca 2þ concentration. The d 18 O of water and Pirenella from the same sample site exhibits a strong correlation (R 2 ! 0.85) with a slope of~1, suggesting that the shells may be a useful chemical archive for the isotopic composition of past oceans. The d 18 O and d 13 C of the shells correlate positively, likely reflecting greater sequestration of 12 C into organic matter in more restrictive evaporative settings. The intercept of the d 18 O and d 13 C correlation shifts between dry and wet seasons, and is interpreted to reflect average seawater temperature differences during recent growth. There is also a strong correlation (R 2 ! 0.85) between shell d 18 O and measured water salinity, reflecting their mutual control by degree of evaporation. The Sr 2þ content of the gastropods does not correlate well with any measured oceanographic parameter, or show evidence of systematic seasonal change.
A mechanistic model was developed to assist with design of constructed wetlands intended to treat industrial wastewater in the Arabian Gulf region. The model is deterministic in nature and thus allows explicit evaluation of the fate and transport of wastewater constituents throughout constructed wetlands to assess their efficacy in treatment. Although the model was developed for the purpose of evaluating treatment wetlands in the hot and arid climate of the Middle East, the model is generalized in order to allow users to simulate a wide range of climates, any type of wetland, with any configuration, and any selection of material and plants. The model simulates the majority of physical, chemical, and biological processes that could occur in wetlands that are responsible for the removal of constituents. The model is designed to be flexible enough to allow the simulation of any number pre-selected constituents or other constituents of the user’s choice made based on the quality of influent. The model relies on a large body of existing literature to formulate each process. The model development discussed in this report and the resulting model, CWM, is considered “in progress”. During the present stage, the model framework and algorithms have been developed and made functional. Subsequently, model formulations will need to be validated, model limitations analyzed and addressed, and model refinements made, before and during use in full-scale operations and design. As such, it is recognized that the present stage of model development is “experimental”, and future refinements of the model are anticipated. Model results at this time consist of evaluation of key model features and how they perform in Middle Eastern climates.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.