Aerobic degradation of BTEX compounds by Streptomyces species isolated from activated sludge and agricultural soils.

In this study, we tested the ability of Streptomyces to use for their growth benzene, toluene, ethylbenzene, and o-, m-, p-xylenes as sole source of carbon and energy. These bacteria were isolated from agricultural soils and activated sludge samples from a wastewater treatment plant. The results show that Streptomyces are capable of degrading at least one of the BTEX compounds. Among them, 3 isolates from activated sludge called (U, F and V) and a single isolate (SA13) isolated from an agricultural soil, can use as the sole source of carbon and energy, all of these BTEX compounds at concentrations of 1500 mg/L. Based on the analysis of the 16S rRNA gene sequence, two active strains were identified as Streptomyces fimicarius, Streptomyces cavourensis, Streptomyces flavogriseus and Streptomyces pratensis. These strains can be excellent candidates for the bioremediation of the telluric and aquatic sites polluted by these xenobiotics.

Assessment of water quality at the largest dam in Algeria (Beni Haroun Dam) and effects of irrigation on soil characteristics of agricultural lands.

Beni Haroun Dam is a vital water resource for both potable water and irrigation in eastern Algeria. This study assessed water quality at the dam and investigated the impacts of this water on some soil characteristics of irrigated lands. The physicochemical parameters of the water were measured monthly at eight sites and related to soil characteristics sampled from six irrigated areas, which were compared to non-irrigated soils. The chemical facies of the water were chloride sulfate and calcium magnesium. The water had low levels of cadmium (8.9 µg/L) and lead (4.55 µg/L), excessive contents of chloride and bicarbonate, while pH ranged between 6.5 and 8.4. High levels of electrical conductivity were measured in 39% of samples that exceeded standard for irrigation use. Richard diagram identified four classes of water: (i) C3S1 with 61.5% of samples having moderate or poor quality, (ii) C4S1 (30.2%) having poor or bad quality, (iii) C4S2 (5.2%) having very bad quality, and (iv) C5S3 (3.1%) determined unsuitable for irrigation. A Wilcox diagram revealed that 58% of samples had good quality while 42% were inappropriate for irrigation. Soil pH, EC and OM increased in irrigated soils, particularly in the surface horizon, compared to the control sites; whereas total CaCO3 decreased at all soil depths measured. High levels of bioavailable lead (35.82 µg/g) and cadmium (0.22 µg/g) were recorded in the surface soil. The study suggests that adequate protection measures with appropriate guidelines for various water and soil parameters are needed to minimize the detrimental effects of irrigation water on agricultural lands.

Sources and levels of particulate matter in North African and Sub-Saharan cities: a literature review.

In order to assess the significance of PM in ambient air, it is necessary to evaluate their physical and chemical characteristics as well as identify their major emission sources. On a global scale, particulate matter in the atmosphere arises mainly from the combustion process of motorized vehicles, but natural sources are still considered as the major contributors. In Africa, PM emissions differ from those in developed countries; human activities such as biomass burning in households, poor household waste management, and the high number of diesel-powered vehicles are the predominant anthropogenic sources. Natural contributions are also observed. Saharan dust and savanna fires are the most common atmospheric natural sources of particulate matter. The present literature review gives an overview of the status of air quality in African cities and highlights the various sources of particulate matter emissions and local human activities specific to each African region. This could likely serve as a reference to evaluate the current air quality in this region and will be a useful tool in the future to develop pollution mitigation strategies at the source. Recommendations are proposed in the conclusion in order to reduce emissions from their sources, taking into account the low-income African countries.