Evaluation of human fecal contamination in irrigation water used in Urban Gardens of Salvador/BA

Abstract

In Brazil, the main problem regarding natural water bodies is the incorrect disposal of 18 domestic sewage directly into rivers. This constant degradation of water bodies combined with 19 lack of basic sanitation compromises the environment health, facilitating waterborne diseases. This 20 problem can become more sensitive when contaminated water is used for irrigation of agricultural 21 crops. Due this problem, water needs to be analyzed and is necessary to identificate the source of 22 the problem. To protect consumers from contaminated water, CONAMA’s resolution was created 23 (Resolução Nº 357/2005) to identificate the water that are within thee defined standard. Even 24 though, the constant control of these waters is very complicated due to the size of Salvador and 25 quantity of points distributed in all city. This article aims to identify and describe the contaminated 26 urban gardens and identify the possible source of contamination, focusing on specific human 27 bacteria. We performed coliform analysis for identificate urban gardens with fecal contamination 28 and, to identify more specific fecal sources was used Microbial Source Tracking (MST), with 29 Human bacteroides and Lachnospira primers. Using bacterial counts to assess water 30 contamination, 43.8% of the evaluated urban gardens were not suitable for human use and/or 31 irrigation. PCR results indicated 31.25% of the sites with Human bacteroides positive samples and 32 6.3% with Lachnospira positive samples. So, water is being compromised due to the disposal of 33 decomposed organic material or faeces, even with CONAMA’s resolution. Those waters should 34 be monitored and shouldn’t be contaminated, considering the importance they represent to the 35 community.