The Editor
Barbados Underground
Barbados,W.I
Dear Sir/Madam,
According to an article in Barbados Today of 2nd.February 2019, Minister of Energy and Water Resources Wilfred Abrahams had the following to say: “We have come in eight months….. Graeme Hall swamp which was receiving raw sewage for over three years is on the rebound, fish have come back, the water quality is great, smells have gone down, the mosquitoes have been controlled.” He added “that the water in the swamp has remained at acceptable levels since the outfall was commissioned and the Environmental Protection Department has reported that the water quality samples have “comfortably passed” international standards for health and safety. However, oceanographic studies of the beach will be continued to make sure that the 12-inch outfall does not impact the water quality of nearshore or offshore reefs.”
I have some comments to make on the above statements. It is noticeable that no testing seems to have been done on the following: sediments at the bottom of the swamp; the presence of protozoans and lastly the presence of bacteriophages.The protozoan parasites Giardia duodenalis and Cryptosporidium spp.,are pathogens that are resistant to a number of environmental factors and pose significant risks to public health worldwide. “Their environmental transmission is closely governed by the physio-chemical properties of their cysts (Giardia) and oocysts (Cryptosporidium)allowing their transport, retention, and survival for months in water,soil,vegetables (Dumetre and others (2012).“Interaction Forces Drive the Environmental Transmission of Pathogenic Protozoa.’ Applied and Environmental Microbiology.p905-912. Note ,cysts and oocysts are survival bodies that are extremely resistant to different methods of destruction. It really does not make sense to say because the water is less cloudy that microbial conditions have improved significantly. Since sedimentation occurs over time, there is obviously going to be a gradation from the surface to the bottom of the swamp in the concentration of effluents. At each sub-stratum level, there will be different numbers of viable micro-organisms. The numbers being dependent on the ability of the sunlight to penetrate the water. Obviously,if there is significant amount of sewerage entering the swamp and little exiting into the sea (as seems to be the case locally), penetration of sunlight is going to be restricted due to the high levels of effluent present. The most important factor for the removal of viral and bacterial pathogens is sunlight exposure, although other factors such as temperature, dissolved oxygen and pH are also important. Sedimentation is the most important factor for the removal of protozoan pathogens. Therefore, sampling of the of the different strata and sediment have to be done to reflect the true microbial condition of the swamp’s ecosystem. It is interesting to note that the water quality samples have “comfortably passed” international standards for health. I do not know what this is supposed to mean. For example “Guidelines for the microbiological quality of treated wastewater used in agriculture: recommendations for revising WHO guidelines (Blumenthal and others.2000.Bull.WHO 78:9:1104-1116) reported that The United States Environmental Protection Agency (USEPA) and the US Agency for International Development(USIAD) have recommended strict guidelines for wastewater use as being zero fecal coliform bacteria/100 ml for water used to irrigate crops that are eaten raw(compared with the1989 WHO guidelines of < 1000 fecal coliform bacteria/100 ml), and for irrigation of commercially processed and fodder crops. It would be useful if the results of local sampling were made available to the public.
Sediments may provide a stable index of the general quality of the overlying water, particularly where there is great variability in its bacteriological quality. It should be noted also, however, that if the sediments at the bottom of the swamp are disturbed due to excess surface run-off which causes turbulence at the interface of water and sediment,there is an up-welling of sediment which can cause co-mingle,thereby re-contaminating the water.
Viruses which infect bacteria, are known as bacteriophages or simply as phages. Normally,phages infect a specific strain of bacteria. Enteric micro-organisms associated with fecal contamination are E.coli, klebsiella spp.,Shigella etc. There is a direct relationship between the number of phages and the intensity of fecal contamination. It should be noted here that the bacteriophage hijacks the bacterium DNA to make copies of itself,resulting in the death of the host(bacterium). Therefore, the failure to detect pathogenic bacteria does not mean that the water quality is adequate
The outfall which is being used to pump partially treated effluent into the sea,is going to cause an algae bloom,resulting in eutrophication (depletion of dissolved oxygen).As a result,there is going to be what can be termed a desert being formed in the affected area of the sea in which there is an absence of biotic life.
Sincerely
Robert D. Lucas, PH.D and CFS
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