Environmental Studies

This research aimed to determine the radiocarbon content in annual plants growing in rural areas distributed along villages located in the surrounding of a cement factory at Mount Lebanon province. This determination was carried out at different environmental conditions in order to study the factors affecting this content in clean zones, and to map C-14 distribution. As well as, this study also quantified the depletion of radiocarbon in polluted zones in order to assess the anthropogenic impact caused by fossil fuel combustion or Suess effect in urban and industrialized areas.

This study reviewed the detection of pesticides in different surface and groundwater samples collected from South Litani region in South Lebanon using an optimized and validated solid phase extraction method followed by gas chromatography coupled with mass spectrometry. Organochlorine and organophosphate pesticides were mostly noted at levels below the recommended value for individual pesticide in water except pirimiphosmethyl that was recorded at 300.87 ng L−1 in groundwater sample, designated for drinking water and collected in February. DDE concentration exceeded 100 ng L−1 in both surface and groundwater in October. The reported results represent the first Lebanese statistical data illustrating the quantification of pesticides in water over a period of time. More importantly, it draws attention to the need of pesticides’ monitoring programs in the Lebanese water resources.

A new potent Lebanese bacterial isolate, B. licheniformis HE, was able to remove 99.8% of MB color. The finding of the phytotoxicity study manifested the detoxification of decolorized MB, which declared the possible utilization of B. licheniformis HE for the bioremediation of dye containing wastewater.

Pseudomonas sp. DHZ2 and Stenotrophomonas sp. DHZ1 were isolated from tomato rhizospheres along the Lebanese coast and tested for their inhibitory effects on Fusarium sp. and Botrytis sp. The suppressive metabolites produced belonged to the siderophore group and showed maximal activities in fungal growth bioassay at neutral and alkaline pH. These antifungal agents were also highly regulated by iron and phosphorus, which is a distinctive feature of phenazine used in controlling the plant diseases.

Keratinous wastes generated from various industries are increasingly accumulating in the environment. Bacillus licheniformis L. was isolated from soil collected from a Lebanese poultry barn. Purified feather meal and keratin solution were successfully prepared from feathers. Optimization of the factors affecting keratin-degradation and keratinase production was achieved using Plackett Burman design. Determination of amino acids formed in degraded feather and partial purification of the crude enzyme were also determined.

A comparative study of indoor contamination in three private and three official schools in Aley, Lebanon was conducted. Sampling was performed in each school, from the air, desk-surfaces of classes and water taps of bathrooms, for the evaluation of microbial contamination. Official schools showed to be highly contaminated with respect to private schools. Among the three educational levels, the elementary level was the most contaminated.

The isolated Lebanese Candida tropicalis H was able to degrade (after optimization of the nutritional and environmental factors affecting phenol degradation process) 99.91 % of 2000 mg/l phenol within 3 days. A phytotoxicity study revealed that the biodegradation of phenol resulted in its detoxification, which indicated a possible use of phenol containing-effluents in the irrigation of plants after bioremediation process.

The physical, chemical, and microbiological characteristics of seawater along Tyre city coastline, Southern Lebanon, were studied in order to assess its quality and its impact on the marine ecosystem. Untreated sewage discharge into the marine environment contaminates seawater, sediment, and marine flora and fauna. High total and fecal coliforms levels were recorded indicating high microbiological contamination of seawater exceeded the international accepted limit. In addition, pollution by heavy metals is a serious ecological problem; results indicated hifh concentration of iron, copper, cadmium, manganese, zinc, chromium and lead.