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Balancing the needs of current and future generations stimulates investment for sustainable development such as converting waste biomass into biorenewables. Sugar-based ethanol production is a well-investigated and established process, and researchers are now focusing on the transformation of cellulosic biomass to sugar and the application of non-conventional methods for ethanol production. The State of Qatar generates date palm fruit waste of approximately 4505 tons annually, excluding ornamental palms and palms outside the farms that bear nonmarketable date fruits. Date fruit molasses contains fermentable sugars, representing 75% of the total fruit mass, which can offer a good source for bioethanol production through anaerobic fermentation and distillation. On this basis, the valorization of waste date fruits can be an effective zero-waste strategy via biotransformation into bio-renewable materials, hence, contributing to the achievement of sustainable development goals. This paper reviews the potentials and challenges for the utilization of waste date fruits as a bioethanol source and assesses the abundance of waste date fruits as raw material for the conventional bioethanol conversion process. The review also identified conventional and nonconventional processes for bioethanol production and their applicability to Qatar. Finally, this confirmed ample demand for bioethanol ranging from fuel and industrial chemicals to pharmaceutical alcohol.

We present data on elemental concentrations of plankton net tow samples from the Exclusive Economic Zone (EEZ) of Qatar in the Arabian Gulf as part of a broader study of biogenic and lithogenic influences on particulate trace metal concentrations in the surface ocean. There are relatively few analyses of planktonic trace metals and their associated role in the biogeochemical system. We had the opportunity to investigate the composition of plankton in a region heavily affected by dust, a significant factor for phytoplankton growth. Our samples were collected from 2012 to 2015 using trace metal clean net tows with mesh sizes of 50 and 200 microns for measurements of phytoplankton and zooplankton, respectively. Samples were totally digested and analyzed by inductively coupled plasma-mass spectroscopy (ICP-MS). The biogenic portion was determined by subtracting the lithogenic portion from the total concentration. The lithogenic fraction was defined as the concentration of aluminum in the sample multiplied by a [Me]/Al ratio. Using average Qatari dust for these ratios generated a significant amount of overcorrection, so ratios were established using average continental crust (UCC). This method still caused some overcorrection for the lithogenic portion resulting in negative excess values for barium, molybdenum, and lead. These same elements showed the least consistency between measurements. For the other elements, a relative stoichiometry for plankton was determined as Fe > Cu ≈ Zn > As ≈ Cr ≈ Mn ≈ Ni ≈ V > Cd ≈ Co. We also found a significant near shore enrichment for 9 out of 13 elements analyzed, indicative of a possible influence of pollution. Acknowledgement This study was made possible by a grant from the Qatar National Research Fund under the National Priorities Research Program award number NPRP 6-1457-1-272. The abstract contents are solely the responsibility of the authors and do not necessarily represent the official views of the Qatar National Research Fund.

Alkalinity (Alk) and (dissolved inorganic carbon) DIC were measured on high resolution seawater samples, collected on November 2018 and May 2019 at seven stations in the Exclusive Economic Zone (EEZ) of Qatar. Calculated surface PCO2 averaged 472 matm in 2018 and 447 matm in 2019. Thus, the Arabian Gulf is degassing CO2 at present and will not take up atmospheric CO2 until 2042. Ocean acidification is not yet an issue in the EEZ of Qatar. The elevated PCO2 values are due to CaCO3 formation. Normalized NAlk and NDIC were calculated to remove the impact of increasing salinity. NAlk and NDIC decrease corresponding to a CaCO3/OrgC removal ratio of 2/1. We calculated the nitrate corrected and salinity normalized tracer, Alk*. Values of Alk* were negative, and the change in Alk* relative to Hormuz (DAlk*) indicated that there has been an average decrease of Alk* of -130 mmol kg-1. This decrease is due to CaCO3 formation but previous studies found no evidence for coccolithophorids. One obvious possibility is that Alk removal is due to CaCO3 formation in coral reefs. However, recent study of the composition of particulate matter found that the average particulate Ca concentration was 3.6%, and was easily acid soluble (Yigiterhan et al., 2018). These results suggest that a significant amount of particulate CaCO3 is present in the water column. One hypothesis is that the particulate Ca comes from carbonate rich atmospheric dust. Using Al as a tracer for dust and the average Ca/Al ratio in Qatari dust can only explain about 3% of the particulate Ca. An alternative hypothesis is that particulate CaCO3 may form in the water column due to abiological CaCO3 formation, as proposed recently for the Red Sea (Wurgaft et al., 2016). Precipitation of CaCO3 may be induced by the large inputs of nucleation sites in the form of atmospheric dust.

Dissolved inorganic carbon (DIC) and total alkalinity (TA) were sampled in December, 2018 and May, 2019 in the Exclusive Economic Zone (EEZ) of Qatar in the Arabian Gulf. pCO 2 calculated in surface seawater averaged 459 ± 61 matm and was supersaturated with respect to the atmosphere. The region was degassing CO 2 to the atmosphere and the flux was about 1.25 mmol C m -2 d -1 . The origin of this excess CO 2 must be due to CaCO 3 precipitation. The horizontal relationship between salinity-normalized total alkalinity (NTA) and dissolved inorganic carbon (NDIC) showed that CaCO 3 formation was more important, relative to net biological productivity, than in the open ocean. The tracer Alk* has values primarily determined by CaCO 3 formation and values of Alk* ranged from -50 to -310 mmol kg -1 , which is consistent with substantial CaCO 3 formation. DAlk* increased with increasing distance northward from Hormuz. The rate of calcification calculated from the air-sea flux of CO 2 (5.6 mmol C kg -1 y -1 ) and from DAlk* (5.9 mmol C kg -1 y -1 ) agreed well. However, CaCO 3 formation by net calcification in coral reefs is unlikely as they have limited distribution and have been severely damaged by past coral bleaching. There are high concentrations of excess particulate Ca in the water column that cannot be accounted for by input of CaCO 3 -rich Qatari dust. Carbonate forming plankton are absent in the water column. We propose that abiological, heterogeneous calcite precipitation (HCP) may be occurring. The mechanism is unknown but nucleation by CaCO 3 -rich Qatari dust may assist this process.