Little Egret (Egretta garzetta) as a bioindicator of trace element pollution in Tunisian aquatic ecosystems

The Little Egret, Egretta garzetta, has breeding colonies in the island of Chikly (in the lake of Tunis) and in Thyna saltpans (in the gulf of Gabès), two important Tunisian wetlands that are strongly affected by anthropogenic activity. Here, we used E. garzetta chick feathers for environmental monitoring of breeding grounds of this species. Since trophic ecology is fundamental when interpreting contamination levels, our approach combined both trace-element (Hg, Pb, Cd, and Se) and stable-isotope analysis of ??¹³C, ??¹⁵N, and ??³⁴S. Hg, Se, and ??¹⁵N levels were higher in specimens collected on Chikly than in Thyna. These observations highlight the degree of eutrophication of the lake of Tunis. Yellow-legged gulls (Larus michahellis) breeding in the same areas also feeds in the lake and attains similar concentrations of Hg and Se. In Thyna, egrets and gulls exploit distinct foraging habitats, as demonstrated by stable isotope analysis. The highest Hg and Se concentrations were found in Thyna. This result is consistent with greater exploitation of marine resources from the gulf of Gabès.     

Communicating About Bioenergy Sustainability

Defining and measuring sustainability of bioenergy systems are difficult because the systems are complex, the science is in early stages of development, and there is a need to generalize what are inherently context-specific enterprises. These challenges, and the fact that decisions are being made now, create a need for improved communications among scientists as well as between scientists and decision makers. In order for scientists to provide information that is useful to decision makers, they need to come to an agreement on how to measure and report potential risks and benefits of diverse energy alternatives in a way that allows decision makers to compare options. Scientists also need to develop approaches that contribute information about problems and opportunities relevant to policy and decision making. The need for clear communication is especially important at this time when there is a plethora of scientific papers and reports and it is difficult for the public or decision makers to assess the merits of each analysis. We propose three communication guidelines for scientists whose work can contribute to decision making: (1) relationships between the question and the analytical approach should be clearly defined and make common sense; (2) the information should be presented in a manner that non-scientists can understand; and (3) the implications of methods, assumptions, and limitations should be clear. The scientists’ job is to analyze information to build a better understanding of environmental, cultural, and socioeconomic aspects of the sustainability of energy alternatives. The scientific process requires transparency, debate, review, and collaboration across disciplines and time. This paper serves as an introduction to the papers in the special issue on “Sustainability of Bioenergy Systems: Cradle to Grave” because scientific communication is essential to developing more sustainable energy systems. Together these four papers provide a framework under which the effects of bioenergy can be assessed and compared to other energy alternatives to foster sustainability.     

Greenhouse Gases in Cold Water Filaments in the Arabian Sea During the Southwest Monsoon

 The distribution of partial pressure of carbon dioxide and the concentrations of nitrous oxide and methane were investigated in a cold water filament near the coastal upwelling region off Oman at the beginning of the southwest monsoon in 1997. The results suggest that such filaments are regions of intense biogeochemical activity which may affect the marine cycling of climatically relevant trace gases. Received: 1 March 1999 / Accepted in revised form: 16 June 1999     

Impact of Fenton and ozone on oxidation of wastewater containing nitroaromatic compounds

Fenton and ozone treatment was investigated at laboratory scale for the degradation of aqueous solutions of nitrobenzene (NB).Effects of reactants concentration (O3,H2O2,and Fe(II)),temperature,and pH on NB degradation were monitored.Reaction kinetic of these processes was also assessed.A rapid reaction took place for Fenton process at higher initial concentration of H2O2,higher temperatures,and more acidic conditions(pH 3).Similarly, ozonation reaction exhibited rapid rates for higher ozone dose,higher temperatures,and more basic conditions(pH 11).Complete NB degradation in 65 min Was achieved using Fenton process.The conditions of complete elimination of 100 mg/L of initial NB concentration,were 250 mg/L of H2O2 concentration,pH 3,and 10 mg/L of Fe(Ⅱ) concentration.Under these conditions,55% organic carbon elimination Was achieved.Total organic carbon mineralization Was attained in 240 min reaction time by Fenton process with 900 mg/L of H2O2 concentration,and 30 mg/L of Fe(II) concentration.Fenton reaction showed a pseudo-first order kinetic;the reaction rate constant Was ranged from 0.0226 to 0.0658 min-1.Complete NB degradation wag also achieyed for an ozone dose of the order of 2.5 g/L.The ozonation Was studied at different ozone doses.different initial pH(7-11)and at difierent temperatures(15-35℃).NB ozonation kinetic Was represented by a bi-molecular kinetic model which was reduced to pseudo-first order kinetic.The pseudo-first order reaction rate constant was determined to increase at 20℃ from 0.004 to 0.020 min-1 as the used ozone increased from 0.4 to 1.9g/L.     

Impact of invasive mammal species on natural ecosystems: An example of the Prioksko-Terrasnyi Biosphere Reserve

On the basis of Annals of Nature of the Prioksko-Terrasnyi Biosphere Reserve, its colonization by invasive mammal species and the current state of their populations have been analyzed. In the mammal fauna of the reserve, 13 out of 60 species can be classified as invasive. They differ in the degree of impact on the biota. The house mouse, Norway and black rats, and European bison have virtually no effect on natural ecosystems; the effect of the muskrat, raccoon dog, American mink, red and axis deer is insignificant; and that of stray dogs and Tartarian roe deer is considerable. The European beaver and wild boar play an environment-forming role. The impact of beaver activities is strong but local, whereas activities of wild boars put into question the very possibility of conservation and analysis of representative biosphere areas and biological diversity in the reserve.     

Rapid release of heavy metals and anions from polyethylene laminated paper cups into hot water

Polyethylene laminated disposable paper cups are commonly used as a container for hot drinks, yet there is limited knowledge on the transfer of contaminants from the cup to the drink. Here we poured 95^?C hot water in 14 cups, to simulate the preparation of hot beverage for daily use. We studied the water composition after 15 min by inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography. Results show the presence of metals such as vanadium, chromium, copper, cobalt and arsenic at concentration ranging from 0.04 to 1.80 µg/L. Nitrate, nitrite, chloride, bromate, fluoride and sulfate ions were also detected at concentration from 0.003 to 49.21 mg/L. All concentrations are below the WHO maximum permissible limits in drinking water. However, the levels of vanadium at 1.24 µg/L and fluoride ions at 1.03 mg/L are likely to induce a health risk by bioaccumulation after long-term water ingestion. Therefore paper cups composition should be modified to avoid the release of contaminants in hot drinks.

     

Occurrence of toxic metals and their selective pressure for antibiotic-resistant clinically relevant bacteria and antibiotic-resistant genes in river receiving systems under tropical conditions

Environmental Science and Pollution Research - The co-occurrence of heavy metals, antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) from hospital effluents spreading into...     

Microfibrillated Cellulose-Silver Nanocomposite Based PVA Hydrogels and Their Enhanced Physical,Mechanical and Antibacterial Properties

Journal of Polymers and the Environment - Modification of cellulose with silver nanoparticles produces various nanocomposites with significantly developed properties. This work aims to prepare a...     

Metals in agricultural soils and plants in Egypt

Since analysis of both soil and plants are useful to assess contamination of a geographic area, concentrations of five representative metals: copper (Cu), zinc (Zn), cadmium (Cd), lead (Pb), and iron (Fe) in soil and associated plants were measured by atomic absorption spectroscopy. Samples were collected from four different Egyptian regions (El-mehala El-kobra, Kafr El-Sheikh, Kafr El-zayat, and Al-fayoum) during spring and summer 2010. Concentrations of the selected metals in agricultural soils were significantly different among locations and seasons. Concentrations of Cd and Fe in soils at the four locations exceeded the maximum allowable concentrations for Cd (8 mg/kg, dry mass (dm)) and Fe (1000 mg/kg, dm). Accumulation was different for clover and cotton. Clover blossoms grown in soil from Kafr El-zayat contained the greatest concentrations of Cu, Zn, Pb, and Fe. Cotton flowers from El-mehala El-kobra accumulated the highest levels of Cd. Concentrations of Cd and Pb in both clover and cotton flowers from the four locations exceeded maximum allowable concentrations (3 mg/kg, dm) for both Cd and Pb. Using such agricultural soils for cultivation of edible crops for consumption may result in chronic hazards to human health.     

A comparative study of the toxicity of lead and its impact on the carbohydrate metabolism and some haematological parameters of cichlid fish,oreochromis niloticus and catfish,clarius gariepinus from saudi arabia

Fresh and healthy specimens of Oreochromis niloticus (mean weight 70.5± 1.23 g and mean length, 12.3± 1.5cm) and Clarias gariepinus (mean weight, 41.8±2.3 g and mean length 13.78 ± 1.2 cm) were exposed to heavy metal lead, ranging in concentration from 10 to 18 mg L^‐1 for O. niloticus and 20 to 28 mg L^‐1 for C. gariepinus respectively. The 96 h LC₅₀ for both the species was computed as 12.45 mg L^‐1 (O. niloticus) and 22.65 mg L^‐1 (C. gariepinus). The cichlid fish was exposed to sublethal concentration of lead (2, 4 and 6 mgL^‐1) and catfish (4, 8 and 12 mgL^‐1). The erythrocytes count, haemoglobin concentration, haematocrit and the value of serum glucose increased significantly (P < 0.01), whereas leucocytes count, serum protein and serum triglyceride after intoxication declined in both the species with the same pattern but in different quantity. After 96 h of time a significant depletion of muscle and liver glycogen was noted, being greater in muscle (16.7% in O. niloticus) and in liver (15.9% in C. gariepinus). The response of fish to lead was dose dependent.