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In the current work, we investigated the concentration of Ni and Pb in different organs of Phragmites australis to evaluate its potential application as a phytoremediator to remove these two metals from contaminated water and sediment in Lake Burullus (a Ramsar site in Egypt). Above- and below-ground biomass of P. australis, water and sediment were sampled monthly for 1 year at six sites of Lake Burullus (three sites represent each of the northern and southern parts of the lake) using six randomly distributed quadrats (each of 0.5 × 0.5 m) at each sampling site. Significant variation was detected for Ni and Pb concentrations in the sediments and waters between the northern and southern sites of the lake. The biomass of P. australis in the southern sites was greater than that in the northern sites; in addition, the above-ground biomass was higher than the below-ground biomass. The above-ground organs accumulated higher concentrations of Ni and Pb than the below-ground organs. The Ni and Pb standing stocks data indicated that the organs of P. australis extracted higher amounts of Ni and Pb per its area from the southern rather than the northern sites. In the current study, the Ni and Pb above-ground standing stocks increased from the early growing season (February) and reached its peak during August and then decreased. The highest monthly Ni and Pb standing stock (18.2 and 18.4 g m− 2, respectively) was recorded in the above-ground organs of plants in the southern sites in August. The bioaccumulation factor of Ni was 157.6 and 153.4 in the northern and southern sites, respectively, whereas that of Pb was 175.3 and 158.3. The translocation factor of Ni and Pb from the below- to above-ground organs was generally > 1. Thus, this reed species is a potential candidate for Ni and Pb phytoextraction. Based on our results, P. australis could be used for the extraction of Ni and Pb to reduce the pollution in Lake Burullus, if the above-ground biomass is harvested at its maximum value in August, as was the case regarding the maximum standing stock of Ni and Pb.

Precise knowledge of the soil organic carbon (SOC) stocks under various land uses is needed to meet the Kyoto Protocol and for the sustainability of natural resources. The purpose of the present st...

Groundwater from the Nubian Sandstone aquifer at Farafra Oasis in the Western Desert of Egypt has been investigated using chemical tracers and environmental isotopes to clarify the hydrochemical features of this aquifer. The majority of the collected samples are characterized by Ca-Cl water type, which may be attributed to dissolution of the carbonate-rich sediments. Calculated saturation indices show that the main hydrogeochemical processes were the dissolution of carbonates and evaporites and the precipitation of Fe-rich minerals. Temperatures calculated using the K-Mg geothermometer show that the reservoir temperature ranges from 58°C to 121°C. The groundwater samples have δD and δ18O values similar to the isotopic content of the Nubian aquifer palaeowater in the Western Desert. Additionally, the isotopic composition suggests that there is no active potential current recharge from the local precipitation. Gamma spectrometry of 226Ra, 232Th and 40K activities indicates that the groundwater of the Nubian aquifer is safe with respect to radioactivity. Groundwater in Farafra Oasis is the main source of irrigation and drinking water for local residents. All the samples are excellent for irrigation uses for all types of crops. It is suggested that the water samples may require some treatment regarding the high iron content before usage as drinking water. Supplementary material:https://doi.org/10.6084/m9.figshare.c.4938252

Summary: The aim of this study was to conduct the first comprehensive evaluation of carbon stock in the sediments of Avicennia marina (black mangrove) and Rhizophora mucronata (red mangrove) along the coastline of an arid region (Farasan Islands, Saudi Arabia). Such information is necessary for the development of any management plan for the mangrove ecosystems along the Saudi Red Sea islands and provide a rationale for the restoration of mangrove forests in Saudi Arabia. A. marina and R. mucronata locations showed significant (P < 0.001) differences in sediment bulk density (SBD) and sediment organic carbon (SOC) concentration with higher mean values for both in the sediments of A. marina. Considering the whole depth of sediment sampled (0–50 cm), the highest value of SOC stock (12.3 kg C m−2) was recorded at A. marina locations and the lowest (10.8 kg C m−2) at R. mucronata locations. Thus, the SOC stock of A. marina was greater than that of R. mucronata by 114.3%. Consequently, considering the rate of carbon sequestration and the area of mangrove forests (216.4 ha), the total carbon sequestration potential of mangroves in the Farasan Islands ranged between 10.3 Mg C yr−1 and 11.8 Mg C yr−1 for R. mucronata and A. marina locations, respectively. Thus, it is necessary to protect and restore these ecosystems for the sequestration of carbon and for their other valuable ecosystem services. Keywords: Blue carbon, Carbon sequestration, Carbon stocks, Climate change, Coastal ecosystems

The current study aims at forming new prediction models to be employed in the approximating the possible uptake of a range of 10 heavy metals (HMs) (Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn) by Hordeum vulgare tissues including roots, shoots and grains following its growth in soil amended with sewage sludge (SS) using conditions employed in greenhouses. The present study determined an insignificant difference between the actual and predicted quantities of the HMs in the three tissues using t values. The majority of the predicted quantities of the HMs were acceptable with the exception of Cd in the shoots, Cu in grains and Pb in roots. Consequently, it is possible to use these models in assessing the cultivation of barley plants in soil amended with SS in a safe way, while simultaneously monitoring any potential risks to the health of humans.

The present study was conducted to investigate the potential of the emergent macrophytes Phragmites australis to remediate nutrients and restore an eutrophic wetland (Lake Burullus, Egypt). The plant was sampled monthly for one year from 6 sites distributed equally along the northern and southern parts of this lake. Monthly significant variation in all investigated sediment and water nutrients for the northern and southern sites was recorded. The biomass of P. australis in the southern sites was greater than that of the northern sites; in addition, the above-ground biomass was greater than the below-ground biomass. The above-ground biomass increased from February until it reached its maximum during August and then decreased again. Likewise, the highest nutrient concentrations in the different tissues were recorded at the beginning of the growing season during winter and early spring and then gradually decreased with increasing plant biomass. Moreover, the nutrient content (g/m2) increased from the early growing season (February) and reached its peak during April–August and then decreased. Based on our results, P. australis could be used for the extraction of nutrients to reduce the eutrophication in Lake Burullus, if the above-ground biomass is harvested at its maximum value in August, as was the case regarding the maximum content of most nutrients.

The sources of land degradation in many watersheds are runoff and erosion. In order to delay this degradation resulting in the loss of soil fertility, a system for its quantification needs to be established. Erosion severely impacts our natural capital and requires several studies and prevention and management steps. This research focuses on validating the revised universal soil loss equation (RUSLE) method through evidence from remote sensing (RS) and the Geographic Information System (GIS) in the watershed of the Inaouene river upstream of the Idriss 1st dam in the Taza region (northeast of Morocco). In this context, the approach adopted was performed, consists in combining the revised universal soil loss equation (RUSLE) to quantify erosion and GIS to spatialize the factors responsible for water erosion and soil loss (climate, soil, vegetation, and topography) GIS to produce a map of erosion risk. The results achieved show that the Inaouene watershed is characterized by an average climatic aggressiveness, a sparse vegetation cover without any safeguards, moderate to high erodible soils with a maximum ranging from 50 to 150 t/h/year. Topography characterized by high (50%) to moderately broken reliefs. The human intervention remains the most mattering factor in the embrittlement and the accentuation of the soils vulnerability for erosion for every dominant natural factor. The results of this study could be of use in prioritizing areas for soil conservation measures and watershed development and management. It is a tool for decision-makers, planners, and decision-makers in soil and water conservation decision-making to implement anti-erosion strategies to reduce the impact of erosion.

The principal objective of this study is to generate mathematical regression equations that facilitate the estimation of the extent to which Eichhornia crassipes (C. Mart.) Solms, water hyacinth, absorbs heavy metals (HMs) into four plant organs (laminae, petioles, roots, and stolons). This study considers the absorption of nine HMs (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn), and the E. crassipes evaluated in this study were located in three irrigation canals in the North Nile Delta in Egypt, with sampling being conducted in both monospecific and homogenous E. crassipes. Samples of both E. crassipes and water were collected on a monthly basis during one growing season. Analysis of the water samples showed that the HM concentrations ranged from 1.1 μg/l for Cd to 2079.8 μg/l for Fe. All HMs were more concentrated in the E. crassipes roots than in any other organ. Typically, there was a significant correlation between the HM levels in the water and the HM levels in the E. crassipes organs. E. crassipes was documented by a bioconcentration factor > 1.0 for all HMs. The translocation factor in this study was, Ebrahem M. Eid extends his appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through Research Group Project under grant number RGP.1/60/42. Aljawhara H. Almuqrin acknowledges the support from the Deanship of Scientific Research at Princess Nourah bint Abdulrahman University through the Fast-track Research Funding Programme.

Modelling river water level (WL) of a coastal catchment is much complex due to the tidal influences on river WL. A hybrid machine learning model based on relevance vector machine (RVM) and improved grasshopper optimization (IGOA) is proposed in this study for modelling hourly WL in a catchment located in the east coast of tropical peninsular Malaysia. Considering the non-linear relationship between inputs and output, a recursive elimination filter based on support vector machine (SVM-RFE) was employed for the selection of the best combination of inputs from antecedent WL and rainfall data for the prediction of WL one hour ahead. The performance of IGOA was compared with classical GOA and particle swarm optimization (PSO) algorithms. Besides, the performance of the hybrid RVM model was compared with the artificial neural network (ANN) models hybridized with the same optimization algorithms. The SVM-RFE selected 1-, 12- and 24-lags WL data and 1-lag rainfall data as the most potential inputs. The relative performance of the models revealed the reliability of RVM-IGOA in WL prediction of a coastal catchment. Significant improvement of model performance was noticed after optimization using IGOA with Nash-Sutcliff Efficiency (NSE) of 0.986 and 0.981, and Kling-Gupta Efficient (KGE) of 0.981 and 0.974 for RVM-IGOA and ANN-IGOA respectively, compared to the models hybridized using other optimization algorithms with NSE between 0.969 and 0.971, and KGE between 0.890 and 0.908. The study indicates the selection of predictors based on their non-linear relations with WL and better optimization of model parameters can improve model performance in simulation of highly complex hydrological phenomena like tidal river WL in a tropical coastal catchment.

In this study, Aqua-Moderate Resolution Imaging Spectroradiometer (MODIS) Collection (C6) and C6.1 Dark Target aerosol optical depth (AOD) retrievals at 3 km (DT3K) and 10 km (DT10K), Deep Blue AOD retrievals at 10 km (DB10K), and combined DT and DB (DTB) AOD retrievals at 10 km resolutions were validated from 2002 to 2014 against ground-based sunphotometer AOD measurements obtained from the Chinese aerosol remote sensing network (CARSNET). The CARSNET AOD data were obtained for sites at Mt. Waliguan (MW), Lanzhou (LZ), Ulate (UL), and Zhengzhou (ZZ) located in the Yellow River basin (YERB) region, China. Errors and agreement between satellite and ground data were reported using Pearson&rsquo, s correlation (R) and relative mean bias (RMB). Results showed that the DT3K C6.1 highest quality flag (QF = 3) AOD retrievals were well correlated with the sunphotometer AOD data, with an R of 0.82 and an RMB of 1.01. Overestimation and underestimation in DT AOD retrievals were observed for AOD &gt, 1.1 and AOD &lt, 1.1, respectively. A significant underestimation of 37% in DB10K AOD retrievals was observed across all the sites except ZZ, which was indicated by a low-value RMB (0.63). Spatial distribution maps showed high AOD values (&gt, 0.8) over the lower part of the YERB and low AOD values (&lt, 0.4) across the upstream part of the YERB. This might be due to a large number of aerosol emissions over the lower developed areas and a scarcity of aerosols over the upstream mountain areas. Overall, this study supports the use of DT10K C6.1 AOD retrievals over the western semi-arid and arid regions of the YERB and DTB10K AOD retrievals over the north-central water system and eastern plain regions of the YERB.

Increased knowledge of heat island surfaces (HIS) and intense heat island surfaces (IHIS) in urban environments is critical for the mitigation of excess urban heat and the associated burden on power grids. In this study, we propose a robust thermal remote sensing solution for the delineation of HIS and IHIS areas in Abha and Khamis, a tourist resort in southern Saudi Arabia. Land surface temperature (LST) classification images were retrieved by applying the Single Channel Algorithm (SCA) to thermal band 10 of Landsat 08 data. The pixels of the LST images were grouped based on temperature ranges using ENVI 5.5 software, and were then delineated into classification images of HIS and IHIS areas. Analysis of these images revealed that the overall area of HIS dynamics in both Abha and Khamis ranged from 562 to 826 km2, with temperature variations between 36.0 °C and 41.0 °C, while IHIS ranged from under 1 to 14 km2, with temperature fluctuations ranging between 40 and 46 °C. The city of Khamis had larger summer HIS and IHIS areas than the city of Abha. This study has a strong potential to support local stakeholders, including urban planners, in tracking and offsetting the negative urban heat island (UHI) effects that result from population growth and an increase in impervious surfaces.

The position of Sinai Peninsula as an area of transit from Africa to Asia and vice-versa, is so strongly reflected on its importance on the projects of sustainable development in Egypt. Wadi El-Arish basin, largest drainage system in Sinai Peninsula, exhibits variable morphologic features due to the impact of the local lithologic, tectonic, topographic features and arid climatic conditions with intermittent flash floods. The present work attempts to determine the flood parameters: peak discharge, runoff volume and time to peak discharge. Due to lack of runoff measurement, Soil Conservation Service (SCS) unit hydrograph method is used to compute the runoff hydrographs. Rainfall data of all effective rainfall stations for 100 years design storm is incorporated in the Hec-1 hydrologic module. Also, the land use and soil type map are used to estimate the water losses and accordingly the excess rainfall which causes runoff. For that, Wadi El-Arish has been subdivided into nine sub-basins; ranging in area from 509 to 6111 km2. Drainage network, geometry and relief aspects were determined for the different sub-basins. The runoff volume ranges from 4.19 to 59.30 million m3. Additionally, geophysical technique in the form of gravity data with geological and hydrological techniques have been employed to delineate groundwater potential zones in Wadi El-Arish catchment area using GIS-based techniques. The resulting GIS model shows that the most favorable areas for groundwater potentiality are located at the southern part of Wadi El-Arish at Wadi Abu Tareifiya sub-basin and to the south of Wadi El-Azariq sub-basin.

The current study aims to form new prediction models to approximate the possible uptake of six heavy metals (HMs) (Cd, Cu, Fe, Ni, Pb and Zn) in Phragmites australis tissues, including stems, leaves and belowground tissues (BGT). Samples of different plant tissues from two populations with different ages and sediments were collected monthly during one growing season (January–December) from 9 sites at Lake Burullus, and the tissues were analysed. A nonsignificant difference was observed between the actual and predicted quantities of HMs in the three tissues using t values, which reflects the goodness of fit of these equations for predicting the uptake of these HMs. Such types of equations may be helpful for evaluating the potential of this plant to phytoremediate these six HMs in Lake Burullus.