Article

Screening analysis of river seston downstream of an effluent discharge point using near-infrared reflectance spectrometry and wavelet-based spectral region selection.

Universidade Federal da Paraíba, CCEN, Departamento de Química, Caixa Postal 5093, 58051-970-João Pessoa, PB, Brazil.
Water Research (Impact Factor: 4.66). 09/2005; 39(13):3089-97. DOI: 10.1016/j.watres.2005.05.018
Source: PubMed

ABSTRACT A methodology for screening analysis of river seston downstream of an industry effluent by using near-infrared reflectance spectrometry was developed. A wavelet transform (WT)-based strategy is used to select a spectral region in which the effect of the effluent on the optical properties of the seston is more evident. The methodology was applied to samples from the River Mumbaba in northeast Brazil. Four sites were monitored: two upstream (1 and 2), one at the discharge point of the effluent (3), and another downstream (4). Soft Independent Modelling of Class Analogies (SIMCA) models were built for site 1 and were then applied to the classification of samples from sites 2 and 4. The results reveal that the WT-based spectral region selection is essential to ensure good sensitivity and specificity with respect to the detection of events associated to the effluent discharges at site 3. In fact, the changes in site 4 caused by the effluent are masked by other environmental factors when the full spectrum is employed.

0 Bookmarks
 · 
161 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Lake Erie is part of the Great Lakes systems in North America, which represent the largest continental lake systems in the world. Anthropogenic eutrophication in the Western Basin of Lake Erie, a Case II environment, has an adverse impact on the surrounding ecosystems and the regional economy. The optical complexity found in Lake Erie is a feature of many aquatic environments making it a challenging setting for remote-sensing applications. To assess the controls on these optical properties, we sampled 20 locations, encompassing a variety of optical environments in the Western Basin and Sandusky Bay during four research cruises. Strong correlations between light extinction and phycocyanin correlation coefficient, r ≥ 0.95, suspended sediment r = 0.90, and chlorophyll-ar ≥ 0.86 indicate that surface conditions are representative down to at least the first optical depth. Application of varimax-rotated principal component analysis to lab-based, hyperspectral reflectance data identified three components related to a diatom/green algae community, and two blue-green algae communities, one of which was associated with suspended sediment. Phycocyanin and chlorophyll-a content inferred using a semi-analytic red/near-infrared algorithm correlated well with concentrations measured in situ using a multiparameter sonde. Chlorophyll-a retrievals from a regional, blue : green algorithm developed for the Western Basin of Lake Erie compared well with retrievals from the semi-analytic algorithm for all samples from the Western Basin and 25% of samples from Sandusky Bay. Chlorophyll-a retrieval errors using the blue : green algorithm occurred when high ratios of suspended sediment to phycocyanin biased samples from the extremely turbid waters of Sandusky Bay. The bias likely resulted when suspended sediment altered the blue : green ratio or when phycocyanin interfered with the chlorophyll-a absorption peaks. This approach can be applied to other Case II environments to provide insights during the design of experimental field studies and for spectral band selection with the next generation of visible near-infrared remote-sensing instruments.
    International Journal of Remote Sensing 10/2013; 34(24):8854-8880. · 1.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper proposes a method for determination of chemical oxygen demand (COD) in domestic wastewater. The proposed method is based on near-infrared reflectance (NIRR) measurements of seston collected from wastewater samples by filtration. The analysis does not require any special reagent, catalyst or solvent. Inherent baseline and noise features present in NIRR spectra are removed by a Savitzky-Golay derivative procedure followed by wavelet denoising. The resulting wavelet approximation coefficients are used for partial-least-squares modelling and subsequent prediction of COD values in new samples. The model is calibrated by using COD values obtained according to the American Public Health Association (APHA) reference method. The proposed method is applied to effluent samples from the anaerobic ponds of the Mangabeira municipal wastewater treatment plant in the city of João Pessoa (Paraíba, Brazil). By comparing the NIRR prediction results with the APHA reference values, a root-mean-square error of prediction (RMSEP) of 19 mg O2 L(-1) and a correlation of 0.97 were obtained. Such results are deemed adequate in view of the joint estimate of the standard error of the reference method, which was calculated as 21 mg O2 L(-1).
    Analytica chimica acta 05/2007; 588(2):231-6. · 4.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Maintaining a clean water supply is one of the key challenges facing humanity today. Pollution, rising population and climate change are just some of the factors putting increased pressure on our limited water resources. Contamination of the water supply presents a high risk to public health, security and the environment; nevertheless, no adequate real-time methods exist to detect the wide range of potential contaminants. There is a need for rapid, low cost, multi-target systems for water quality monitoring. Information-rich, multivariate techniques such as vibrational spectroscopy have been proposed for this purpose. This review presents developments in the applications of vibrational (NIR, MIR and Raman) spectroscopy to water quality monitoring over the past 20 years, identifies emerging technologies and discusses future challenges.
    Critical Reviews in Environmental Science and Technology 10/2011; 2011(Early Version). · 3.38 Impact Factor

Full-text

Download
23 Downloads
Available from
May 15, 2014