Contamination of groundwater by necro-leachate and the influence of the intervening factors in cemeteries of the municipality of Lages – Brazil

ABSTRACT Cemeteries are potential sources of groundwater contamination and, despite the several studies that evidence this sort of contamination, only a few consider how the aspects and characteristics of the unsaturated zone interfere in this process. This study evaluated the quality of groundwater in the areas of two cemeteries under the same precipitation regime, climate and burial practices, but with pedological differences. During one year, the physicochemical parameters potential hydrogen (pH), electrical conductivity, oxidation-reduction potential, dissolved oxygen, total dissolved solids, chemical oxygen demand, total phenols, total phosphorus and ammonia (NH3), as well as the heavy metals cadmium (Cd), lead (Pb), copper (Cu), chromium (Cr), nickel, (Ni) and zinc (Zn), were monitored in the groundwater from two cemeteries located in the urban area of the municipality of Lages, Brazil. Samplings were performed in monitoring wells inside the cemeteries and the local rainfall was registered. The quality of the groundwater from both cemeteries indicates contamination by necro-leachate constituents such as mineral salts, NH3, total phenols, Cd, Cr and Ni, which, besides being harmful to the environment, pose a risk to public health. The precipitation, which had a direct effect on the height of the water level in the groundwater aquifer, increased the levels of contaminants, while the reduced values of cation-exchange capacity (CEC), considering that a large part of the soil is occupied by Al3+ ions, reduced the adsorption potential of the other metals. RESUMO Os cemitérios são fontes potenciais de contaminação das águas subterrâneas e, apesar dos diversos estudos que evidenciam essa contaminação, poucos são os estudos que consideram como os aspectos e características da zona não saturada intervêm nesse processo. Este estudo avaliou a qualidade das águas subterrâneas nas áreas de dois cemitérios condicionados ao mesmo regime pluviométrico, clima e costumes de sepultamento, porém com diferenças pedológicas. Durante o período de um ano foram monitorados parâmetros físico-químicos: potencial hidrogeniônico (pH), condutividade elétrica (CE), potencial de oxidação/redução (ORP), oxigênio dissolvido (OD), sólidos totais dissolvidos (STD), demanda química de oxigênio (DQO), fenóis totais, fósforo total e amônia (NH3) e metais pesados: cádmio (Cd), chumbo (Pb), cobre (Cu), cromo (Cr), níquel (Ni) e zinco (Zn), nas águas subterrâneas de dois cemitérios localizado