Environmental study of the role of anthropogenic factors on the possible pollution of coastal marine waters in Dakhla Bay – Morocco
Abstract
The sites used for breeding and the beaches are ranked in descending order of health in 4 categories A, B, C and D according to the estimate of the microbiological quality and evaluation of the chemical contamination (circular 15.08.12 d 'August 2012). After classification, the target areas are subject to regular health surveillance, intended to verify the durability of the characteristics that have based their classification and to detect possible episodes of contamination. This monitoring covers the measurement of microbiological, chemical (heavy metal) and marine biotoxin parameters in bivalve molluscs, as well as phytoplankton pests in seawater.
The Main objective of the present survey is to make a diagnosis of the state of health of the principal beaches of the region of Dakhla Oued Eddahaba bay in years 2015, 2016 and 2017. Our sampling focused on 4 beaches: Foum Lbouir, El Moussafir, Lakeira, and Tourist Area. Bacteriological analyzes were conducted to identify the microorganisms that are indicative of faecal pollution including faecal coliforms, faecal streptococci and Escherichia coli and their enumeration by the filter membrane method on nutrient media Tergitol7 Agar, Litsky, Slanetz & Bartley.
In addition to microbiological monitoring of seawaters, the air temperature was measured "in situ" using a mercury thermometer, the temperature of the water using a pH meter, the tide (high or low) and finally the estimate of the number of bathers.
The Main results obtained made it possible to classify the four beaches in 3 categories according to the Moroccan standard for monitoring bathing water quality NM 03.7.200. The beaches of the Al Moussafir and Tourist PK25 are classified A. The beaches of Foum Lebouir with medium quality waters is classified A or B. Only the beach of Lakheira is very polluted and classified in category C.
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Introduction
The Moroccan coastline is a diverse, fragile area and today is very much threatened by profound urban and tourist pollution. With a coastline of approximately 3500 km, developing on two Atlantic and Mediterranean maritime facades, the Moroccan coastline occupies a privileged place at the level of the entire coastline of the African continent. The wealth, associated with the strategic space that represents the littoral, made of this last one a major space of development of the country in terms of urbanization, industrial zones and tourist equipments.
The Moroccan coastline is obviously a heritage of great importance for the country. It represents a Mediterranean facade stretching about 460 km from Tangier to Saidia and an Atlantic facade of 2500 km from Tangier to Lagouira.
It is a strategic area with a wide variety of natural and biological resources, including beaches, dunes, lagoons and wetlands. It is under increasing demographic pressure from urban agglomerations and the influence of various industrial, port and tourist activities.
Morocco has a strong tendency to urbanization estimated at 4.4% per year, which is accompanied by a phenomenon of coastalisation of the population. The expanding coastal agglomerations provide the bulk of urban growth with more than 60% of the total urban population of the country [1].
The coastline is also the location of most industrial units; more than 80% of industries are located near coastal areas. The industries are highly concentrated along the Kenitra-Safi axis and especially in the Casablanca agglomeration. This axis concentrates nearly 62% of industrial units and nearly 70% of industrial employment [1].
In addition, through the marine facilities located along the coast, transiting 98% of trade with the outside of this fact Moroccan water are experiencing intense shipping. Thus, hundreds of boats run daily along the Moroccan coast, including tankers and tankers that pose a permanent threat to marine pollution. Similarly, the important fisheries resources consist of more than 7137 animal species providing a fishing potential estimated at 1000 000 annual tons [2].
In recent years, tourism policy has made seaside a priority option and this by the development of certain areas such as Tangier and Agadir which concentrate 70% of the hotel capacity approved. The surge in domestic demand on the seaside has also led to the proliferation of second home projects and the occupation of the public domain, which has led to the emergence of a real lack of health infrastructure and consequently a negative impact on several beaches.
Moreover, the quality of the beaches has become over the years a criterion increasingly used by the general public to choose its holiday beaches. This led the authorities to ensure the protection of beaches against pollution by wastewater and to establish a classification of beaches according to their quality. In 2015, 373 declared beaches suitable for bathing in Morocco.
Conclusion
The assessment of the quality of the beaches that were monitored during the 2015 to 2017 surveys based on the Moroccan standard NM 03.7.200 (Tab.1) and the classification grid made it possible to list the clean beaches and the beaches. improper ranges and prioritize them as follows:
- The beache of Al Moussafir is classified A in all years 2015 to 2017;
- The beache of Foum Lebouir is classified A in 2015 and B in 2017;
- The beach of Tourist PK beach is classified A in all years 2015 to 2017;
- Unfortunately, the Lakheira beach deteriorates from class A to B then to C between 2015 and 2017. This decline was attributed to the increase in the number of tourists and the raw sewage flows discharged directly to the beach level.
In addition, the annual evolution of beach safety has shown a significant increase in bacterial contamination during the summer period, which begins in May-June. The highest infections are noted in July and August and decrease in spring and winter. This variation in the level of contamination is explained by the following facts:
- The beginning of the seaside activity by the occupation of the secondary houses at the edge of the beaches and the swimming start at the end of May;
- The school holidays in July August coincide with the maximum contaminations;
- The increase in the number of summer visitors in coastal cities, which has an impact on pollution flows from coastal emissions;
- Increased flow of tourists and Moroccans living abroad.
Observations made in the field during the summer have shown that the density of summer visitors is maximum in the afternoon, it is even more during the weekend (Table 2-10). The flow of holidaymakers reaches its peak especially during the months of July and August; period when all homes, hotels and inns are over-saturated.
The waters sampled at the beaches of Foum Lebouir and Lakheira are of average quality for bathing because of a more pronounced contamination by the indicator germs of fecal contamination. This pollution and degradation of the environment are mainly related to the activities of summer visitors during the summer. The temperature and pH of water are favorable for the survival of bacteria (Table 2-10).
This contamination is aggravated by the lack of infrastructure (garbage cans, toilets, showers, signs, etc.), the lack of liquid sanitation networks and the use of septic tanks and poor solid waste management.
Lakheira beach has an poor quality for swimming. It is a special ecosystem due to the presence of agro industry unit which reject rough wastewaters. In fact, the pollution generated is very impressive because of the tourists and industrial activities.
In fact, the sewage as soon as they arrive in the rivers is diluted by the rains. Similarly, domestic pollution is dampened by industrial and agricultural waste rich in heavy metals and pesticides that prevent the proliferation of microorganisms due to bacterial inhibition by toxicity and eutrophication.
The beaches of the Al Moussafir and Tourist PK25 are of good quality for swimming due to the absence of wastewater discharges and also the low pressure of pollution.
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