Fuzzy comprehensive assessment of metal contamination of water and sediments in Ondo Estuary, Nigeria

A more reliable methodology for evaluating metal contamination of coastal water and sediments using fuzzy comprehensive assessment (FCA) is presented by this study. Ten metals (As, Cd, Cu, Cr, Fe, Mn, Ni, Pb, V and Zn) were investigated in water and sediments from ten sampling sites and formulated into fuzzy matrix based on three contamination classifications of pristine, moderately enriched and extremely impacted categories using regulatory limits as criteria. The products of the matrices from membership function of the observed data and the weight matrices generate indices that classify the degree of metal impact on the sites. The results of the FCA show that the estuary is negatively impacted by metals in a range of 45.5–75.1% membership in the extremely impacted category with potential adverse effects on the ecosystem of the neighbouring Atlantic Ocean. The crude oil exploration activity at site 1 is the major source input of the metals beside Fe and Mn which are natural to the geological structure of the area while domestic waste discharges contribute notably to metal contamination in some sites.

[1]  Awwa,et al.  Standard Methods for the examination of water and wastewater , 1999 .

[2]  Yilmaz Icaga,et al.  Fuzzy evaluation of water quality classification , 2007 .

[3]  M. Enea,et al.  Fuzzy approach to the environmental impact evaluation , 2001 .

[4]  Richard J. Lewis,et al.  Hazardous chemicals desk reference , 1987 .

[5]  L. Hall.  A preliminary investigation into the speciation of trace metals in sediments from the gulf of Paria off the coast of Trinidad , 1991 .

[6]  D. Taylor,et al.  The Acute Toxicity and Bioaccumulation of Some Lead Alkyl Compounds in Marine Animals , 1980 .

[7]  P. Wong,et al.  Biotransformation and Toxicity of Lead in the Aquatic Environment , 1980 .

[8]  Helen M. Regan,et al.  Mapping epistemic uncertainties and vague concepts in predictions of species distribution , 2002 .

[9]  Mehmet Cakmakci,et al.  Fuzzy logic modeling of the dissolved oxygen fluctuations in Golden Horn , 2005 .

[10]  Des Connell,et al.  Chemistry and ecotoxicology of pollution , 1984 .

[11]  Z. Baysal,et al.  Removal of Pb(II) from wastewater using wheat bran. , 2006, Journal of environmental management.

[12]  P. Balls,et al.  Dissolved Trace Metals in the Tay Estuary , 1997 .

[13]  A. Flegal,et al.  Intercalibrated lead concentration measurements in the Atlantic Ocean , 2001 .

[14]  Steven Mackinson,et al.  An adaptive fuzzy expert system for predicting structure, dynamics and distribution of herring shoals , 2000 .

[15]  J. Nriagu,et al.  Trace metals in wild rice sold in the United States , 1995 .

[16]  R. T. Powell,et al.  Analytical intercomparison results from the 1990 Intergovernmental Oceanographic Commission open-ocean baseline survey for trace metals: Atlantic Ocean , 1995 .

[17]  Dong-Hoon Park,et al.  Fuzzy expert system to determine stream water quality classification from ecological information , 1997 .

[18]  Shang-Lien Lo,et al.  Diagnosing reservoir water quality using self-organizing maps and fuzzy theory. , 2002, Water research.

[19]  A. E. Greenberg,et al.  Standard methods for the examination of water and wastewater : supplement to the sixteenth edition , 1988 .

[20]  G. Önkal-Engin,et al.  Assessment of urban air quality in Istanbul using fuzzy synthetic evaluation , 2004 .

[21]  S. Hull,et al.  Trace metal in Scottish Estuarine and coastal sediments , 1997 .

[22]  H. Pekey.  The distribution and sources of heavy metals in Izmit Bay surface sediments affected by a polluted stream. , 2006, Marine pollution bulletin.

[23]  Kun She Low,et al.  Sorption of cadmium and lead from aqueous solutions by spent grain , 2000 .

[24]  William Silvert,et al.  Fuzzy indices of environmental conditions , 2000 .

[25]  B. Fisher.  Fuzzy environmental decision-making: applications to air pollution , 2003 .

[26]  Wang Haiyan,et al.  Assessment and prediction of overall environmental quality of Zhuzhou City, Hunan Province, China. , 2002, Journal of environmental management.

[27]  L. Tuxen,et al.  Integrated risk information system (IRIS) , 1990 .

[28]  N B Chang,et al.  Identification of river water quality using the fuzzy synthetic evaluation approach. , 2001, Journal of environmental management.

[29]  William Ocampo-Duque,et al.  Assessing water quality in rivers with fuzzy inference systems: a case study. , 2006, Environment international.

[30]  Mandalay Grems,et al.  Standards , 1987, CACM.

[31]  U. Borgmann,et al.  Lac Dufault sediment core trace metal distribution, bioavailability and toxicity to Hyalella azteca. , 2006, Environmental pollution.

[32]  Bernard De Baets,et al.  Fuzzy rule-based models for decision support in ecosystem management. , 2004, The Science of the total environment.

[33]  Guoqing Shen,et al.  Status and fuzzy comprehensive assessment of combined heavy metal and organo-chlorine pesticide pollution in the Taihu Lake region of China. , 2005, Journal of environmental management.