Contents of heavy metals in marine algae from Egyptian Red Sea coast

Seaweeds belonging to 14 different genera of Chlorophyta, Phaeophyta and Rhodophyta were analyzed to determine the levels of heavy metals in two areas of the Egyptian Red Sea coast. Among the trace metals analyzed, Mn and Zn showed the highest mass concentrations in the surface seawaters of the two studied areas. However, algae obtained from Suez area had the highest concentrations of the investigated heavy metals than those collected from Mars Alam area. Nevertheless, a high variability of the metal levels occurs among the studied algae and also between the investigated areas. Moreover, Zn was the most abundant metal in the seaweeds of the Suez area, while Pb was predominant in Mars Alam area in red and brown algae. L. farinosa had the highest average concentration factor of Zn in Suez (29161 fold), while it was 20091 fold in E. intestinalis at Mars Alam. The highest value of metal pollution index (MPI) was recoded in L. farinosa (22.0) at Suez. It represents 4.6 fold of that value recorded in L. farinosa at Mars Alam. Among green, brown and red algae in Suez, the highest values of MPI were recorded in Cladophora (mixed sub-species) and H. comuto (18.2 and 18.3), P. pavonia (16.2) and L. farinosa (22.1), respectively; while at Mars Alam, they were recorded in Cladophora (mixed sub-species) (6.6), P. pavonia (3.4) and L. farinosa (4.8), respectively.     

Nitropyridoindoles—Formation,characterization and mutagenicity

Nitration of pyridoindoles (β‐carbolines) was carried out using different nitration methods and structural assignments of these nitro compounds were made using different spectroscopic techniques. The mutagenic activity of these nitro derivatives was studied using Salmonella typhimurium strains TA 98 NR and TA 100 NR in the absence as well as in the presence of S‐9 mix. Only trinitro derivatives were found to be highly mutagenic to strain TA 98 NR.     

Concentration of some polycyclic aromatic hydrocarbons in rain,soil and ground water around Ismailia,Egypt

Residues of acenaphthylene, fluorene, anthracene, pyrene, chrysene, benzo(b)fluoranthene and benzo(k)fluoranthene were monitored in rain, soil and groundwater around Ismailia, in northeast Egypt. Residues detected in rain water in 1995 and 1996 were mainly of relatively low molecular weight. Both acenaphthylene and fluorene were detected in rain for the two consecutive years. Top soil has shown a wider spectrum and higher concentrations of (PAHs) than those detected in deep soil, rain and ground water. Only three compounds, acenaphthylene, fluorene and anthracene were detected in samples collected at 50 cm depth. While no traces of PAHs were detected at 1 m depth detectable concentrations of fluorene and anthracene were monitored in groundwater.     

Use of the MicroResp™ method to assess pollution-induced community tolerance to metals for lotic biofilms

Understanding the ecological status of aquatic ecosystems and the impact of anthropogenic contamination requires correlating exposure to toxicants with impact on biological communities. Several tools exist for assessing the ecotoxicity of substances, but there is still a need for new tools that are ecologically relevant and easy to use. We have developed a protocol based on the substrate-induced respiration of a river biofilm community, using the MicroResp™ technique, in a pollution-induced community tolerance approach. The results show that MicroResp™ can be used in bioassays to assess the toxicity toward biofilm communities of a wide range of metals (Cu, Zn, Cd, Ag, Ni, Fe, Co, Al and As). Moreover, a community-level physiological profile based on the mineralization of different carbon substrates was established. Finally, the utility of MicroResp™ was confirmed in an in-situ study showing gradient of tolerance to copper correlated to a contamination gradient of this metal in a small river.     

Trends in Intra- and Inter-Annual Temperature Variabilities Across Sudan

Four mean temperature variables, namely maximum (MAX), minimum (MIN), mean (MEAN) and diurnal temperature range (DTR), were considered for 14 selected observational stations throughout Sudan. The objectives were to investigate the seasonal and annual regimes, the seasonal and annual trends, the intra-annual variability (IAV) by the coefficient of variation (CV), and the interrelationships between the temperature variables and percent of possible sunshine. A mounting evidence of daytime and nighttime warming since the 1940s until 2005 is presented. The exception is the dry season which is dominated by daytime cooling attributable to the damping effect of dust haze/storms. Apparently, the progressive drought across inland locations has raised the MAXs, and to a lesser extent the MINs, of the wet season over those for the hot season. Accordingly, maximum rates of 0.451 and 0.336 degrees C decade(-1) were found for the nighttime and daytime temperatures, respectively. The extreme eastern and western locations have been frequently dominated by the warmest trend rates obtained nationwide. The prevalence of significant decreases (increases) of DTR is more apparent in the dry, hot and annual series (wet series). Depending on the temperature variable under consideration, many stations possessed significant trends toward either increased or decreased variability of the within-year monthly values, i.e. IAV. The correlation between the time series of annual CV and extreme values for each of the four temperature variables shows generally that warmer climate in Sudan is associated with higher intra-annual temperature variability and vise versa, i.e. the CV is directly correlated with the highest value within the year, but inversely correlated with the lowest one. The findings of this investigation also indicate that the DTR is directly related to percent of possible sunshine, but the relationship of the latter parameter is not so clear with MAX, MIN and MEAN.     

Low-level arsenic exposure is associated with bladder cancer risk and cigarette smoking: a case–control study among men in Tunisia

Although exposure to high levels of arsenic is associated with excess bladder cancer risk, lower exposures generally are not. This study represents the first biomonitoring of arsenic exposure in Tunisia and focuses on a possible association with bladder cancer risk. In this context, 124 male bladder cancer cases and 220 controls were recruited and blood samples were analyzed to determine the concentration of As. The study subjects were stratified into median groups based on concentrations of arsenic in their blood. Blood arsenic (B-As) was significantly two to threefold higher in bladder cancer cases than in controls (p?<?0.05). The arsenic concentrations were significantly higher among both smokers and workers in construction. However, neither drinking water nor seafood was found to be incriminated as exposure sources. The adjusted risk ratios for B-As concentration categories 0.1–0.67 and ≥0.67 μg/L were 0.18 (95% CI?=?0.014–2.95) and 2.44 (95% CI?=?1.11–5.35), respectively. Arsenic levels were not found to be associated with tumor grade or stage. The considerable risk in the category of highest cumulative exposure argues for an association between bladder cancer risk and low-level arsenic exposure. Future investigations with larger samples and using techniques that allow the distinction of the different arsenic species should better elucidate this association. Furthermore, the modulation of arsenic level according to the histological grade may be of potential to be used as a diagnostic marker of the disease process and its possible relationship etiologically.     

Treatment of industrial wastewater containing Congo Red and Naphthol Green B using low-cost adsorbent

The present work investigates the potential use of metal hydroxides sludge (MHS) generated from hot dipping galvanizing plant for adsorption of Congo Red and Naphthol Green B dyes from aqueous solutions. Characterization of MHS included infrared and X-ray fluorescence analysis. The effect of shaking time, initial dye concentration, temperature, adsorbent dosage and pH has been investigated. The results of adsorption experiments indicate that the maximum capacity of Congo Red and Naphthol Green B dyes at equilibrium (q _e) and percentage of removal at pH 6 are 40 mg/g, 93 %, and 10 mg/g, 52 %, respectively. Some kinetic models were used to illustrate the adsorption process of Congo Red and Naphthol Green B dyes using MHS waste. Thermodynamic parameters such as (ΔG, ΔS, and ΔH) were also determined.     

Chemical Compositions and Sources of Organic Matter in Fine Particles of Soils and Sands from the Vicinity of Kuwait City

Fine particles in the atmosphere from soil and sand resuspension contain a variety of organic compounds from natural biogenic and anthropogenic matter. Soil and sand samples from various sites near Kuwait city were collected, sieved to retain the fine particles, and extracted with a mixture of dichloromethane and methanol. The extracts were derivatized and analyzed by gas chromatography-mass spectrometry in order to characterize the chemical compositions and sources of the organic components. The major inputs of organic compounds were from both natural biogenic and anthropogenic sources in these samples. Vegetation was the major natural source of organic compounds and included n-alkanols, n-alkanoic acids, n-alkanes, sterols and triterpenoids. Saccharides had high concentrations (31–43%) in the sand dune and seafront samples, indicating sources from decomposed vegation materials and/or the presence of viable microbiota such as bacteria and fungi. Vehicular emission products, leakage of lubricating oils, discarded plastics and emissions from cooking operations were the major anthropogenic inputs in the samples from the urban areas. This input was mainly UCM, n-alkanes, hopanes, plasticizers and cholesterol, respectively.     

Appraisal of the groundwater balance components from multi-remote sensing datasets in a semi-arid region

Semi-arid regions across the globe are fronting water crises, signaling a challenge to ensure future water security. Given the high inter-seasonal rainfall variability and unrestrained groundwater extraction, the precise quantification of groundwater flow components in an aquifer system is a priority. To address this challenge, we used high-resolution remote sensing (RS) data (Landsat and IRS) and GIS modeling (SEBAL, ArcCN) to spatially quantify major groundwater balance (GWB) components, viz., evapotranspiration (ET), rainfall recharge (R), surface runoff (Q), groundwater extraction (PG), irrigation return flow (IRF), and ultimately changes in groundwater storage (ΔS) in a small semi-arid crystalline representative watershed. Results show that a total of ~?230 mm of groundwater is extracted during 2008–2009, creating a negative impact on the groundwater resource, which is further enhanced by limited recharge and high ET. A decrease of approximately 65 mm in groundwater storage is observed in a single hydrological year, and given a very low specific yield, this decrease will introduce large water level decline. The study establishes that declining groundwater level in the watershed is a direct result of over-extraction, and owing to this scenario, efficient irrigation and land use policies are suggested as potential approaches to minimize extraction specifically in the dry season. Our methodology provides a systematic assessment of vital GWB components at a high spatial resolution and an insight on various sustainable mitigation methods. This methodology is useful in the planning and management of groundwater resources, particularly in water-stressed areas.