Instrument for sunlight extinction measurement in water bodies

Abstract

A comprehensive study aimed at evaluating the occurrence, significance of concentrations and spatial distribution of priority pollutants (PPs) along the Comunidad Valenciana coastal waters (Spain) was carried out in order to fulfil the European Water Framework Directive (WFD). Additionally, PPs concentrations were also analysed in the effluent of 28 WWTPs distributed along the studied area, since these infrastructures are usually considered a significant point source of many of these toxic substances.In coastal waters 36 organic pollutants of the 71 analysed, including 26 PPs (8 of them priority hazardous substances) were detected although many of them with low frequency of occurrence. Only 13 compounds, which belong to four different classes (VOCs, organochlorinated pesticides, phthalates and tributyltin compounds (TBT)) showed a frequency of occurrence above 20% in coastal waters. Toluene was the most ubiquitous pollutant (detected in 100% of the samples) with maximum concentration of 1.6 g/l. All analysed coastal waters showed the presence of PPs, being di(2-ethylhexyl)phthalate (DEHP) the most frequent one (detected in 57% of the samples) reaching concentrations up to 15 g/l. In the results obtained until now, there are four compounds that exceed the established Environmental Quality Standards (EQS): octylphenol, pentachlorobenzene, DEHP and TBT exceeded the annual average concentration (EQS-AAC), and only TBT surpassed the maximum allowable concentration (EQS-MAC).Despite its prohibition, endosulfan and hexachlorocyclohexane (HCH) were detected in 9% and 30% of the samples, respectively, and their concentrations were relatively close to their EQS-AAC value (around the 70 %). The most frequent contaminants determined in coastal waters were also present in WWTP's effluents. Generally, effluents from WWTPs exhibited higher frequency of occurrence and concentration than in coastal waters, except for DEPH.

Influence of Environmental Pollutants on Water Quality and Biochemical Parameters of Fish Tissue

“…In natural waters, it is important to know about the sunlight that penetrates in the water column because there are several water parameters that directly depend on sunlight. One of these parameters is the photosynthetic process that can only take place if the light intensity is above a minimum level [9]. The water quality in the shallow lake is affected by resuspension and settling of bottom sediments at least in two ways.…”

Quantifying Contributions to Light Attenuation in Estuaries and Coastal Embayments: Application to Narragansett Bay, Rhode Island

“…Where E 0 (λ) is the irradiance of the incident wavelength λ as quantum flux density (μmol quanta m −2 s −1 nm −1 ) at the water surface, E1 (λ) is the irradiance of wavelength λ (μmol quanta m −2 s −1 nm −1 ) at a downward distance ℓ 1 = z 1 -z 0 (meter, m), and K 1 is the extinction coefficient of the downward propagating irradiance (m −1 ) (Lee and Rast 1997;Barausse 2008;Civera et al 2011;Oviatt et al (submitted)). The irradiance of the incident wavelength λ can be represented by…”

Current-to-Frequency Converter Based Photometer Circuit

“…The general idea behind the classic photometer schematic diagram shown in Fig. 1, based on the photodiode operating in photovoltaic mode and coupled to a transimpedance amplifier, has found many practical applications [11]- [18]. However, despite the advantages that were mentioned in previous paragraphs, especially the low noise and that the output voltage varies linearly with respect to the photodiode current (i.e., the short-circuit current), the rejection of the photometer circuit to additive noise that contaminates the input signal can be improved.…”