Toxicología ambiental y analítica

Evaluation of Surface Water Quality Impacted by Sewage Overflows from Animal and Residential Lagoon Systems using Principal Component Analysis

Abstract

Abua Ikem, Bob Broz, Jimmie Garth, Samson Tesfaye and Lin Chung-Ho

This study was conducted to: (1) evaluate the water quality of Gans Creek (Missouri, United States), (2) assess the physical and chemical characteristics of two sewage lagoon overflows (confined animal lot lagoon overflow: CALLO, and domestic sewage lagoon overflow: DSLO) discharged into Gans Creek, and (3) understand the most significant analytical variables and major controlling processes influencing Gans Creek water quality using principal component analysis (PCA). Monthly (May 2009-February 2010) sampling was conducted along Gans Creek and at lagoon overflow points. Ammonia-nitrogen (NH3-N) in Gans Creek and the overflows was monitored for another year (March 2010-July 2011) because of its potential toxicity to stream health. Thirty-one variables including pH, electrical conductivity (EC), elemental and anionic species, total nitrogen (TN) and total organic carbon (TOC) were measured in samples. We observed that DSLO samples had the highest level of NH3-N, total phosphorus (TP), TN, TOC and B compared to the corresponding levels in both CALLO and Gans Creek samples. Major stressors for this stream system were dissolved materials and ammonia. PCA showed that the first four rotated components (RC1, RC2, RC3 and RC4) accounted for approximately 60% of the total variability of the dataset. Mineralization (RC1: 20%), sewage overflows (RC2: 19%), diffuse pollution (RC3: 12%), and runoffs from cattle grazing areas (RC4: 9%) were the major controlling processes at the study area. Over twenty water quality determinands were significant in the rotated components. Overflows from the lagoon systems need consistent treatment and management for adequate protection of Gans Creek ecosystem.