Influence of Complexation and pH on Individual and Combined Heavy Metal Toxicity to a Freshwater Green Alga

Starodub, M.E.; Wong, Pierre; Mayfield, C. I.; Chau, Y. K.

doi:10.1139/f87-140

Cited by 82 publications

(34 citation statements)

References 16 publications

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“…The newly-formed iron hydroxides have large surface areas and can bind orthophosphate, thereby limiting phosphorus availability to phytoplankton (Kopacek et al, 2005). In addition, organically-bound Al and other heavy metals may also be liberated by irradiation and may reach toxic levels (Starodub et al, 1987;Kopacek et al, 2005). Winch et al (2002) found that as UVB exposure time increased, DOC concentrations declined and toxicity of some metals to Selenastrum subcapitata increased.…”

Section: Discussionmentioning

confidence: 99%

Effect of ultraviolet and visible radiation on iron lability in boreal and artificial waters

2007

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Dialysis experiments were used to assess lability of Fe in boreal stream waters as well as synthetic solutions with the chelators ethylenediaminetetraacetic acid (EDTA) and 8-hydroxyquinoline in Bold Basal Medium (BBM). It was hypothesized that irradiation (UV and visible) of organic-Fe complexes would result in enhanced movement of Fe across a dialysis membrane with a 100 Da molecular weight cutoff. Irradiation of boreal stream waters at pH 4 with UV plus visible radiation consistently resulted in increased Fe concentrations in the dialysis tubing containing 1.0 mM deferoxamine (a chelator) compared to the dark controls. Signifi cant Fe lability occurred in the absence of UVB and UVA when stream water was exposed to visible wavelengths between 400 and 700 nm, but not when exposed to 550-700 nm. Irradiation of BBM media with EDTA with and without UVA under visible light increased lability of Fe and Co but not Mn, Cu or Zn, relative to dark controls indicating that EDTA binding strength is light sensitive for some metals. In contrast, Fe lability in the presence of 8-hydroxyquinoline was not signifi cantly affected by UVA plus visible light relative to a dark control. If lability is used an indicator of biologically availability, then light intensity and spectral quality likely affects the supply rate of biologically available Fe and perhaps other metals in situ. Light conditions may also affect supply rates of biologically available metals in algal cultures, depending on the chelator used.

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Section: Discussionmentioning

confidence: 99%

Effect of ultraviolet and visible radiation on iron lability in boreal and artificial waters

2007

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“…Metal pollution in aquatic systems is related to pH, i.e., when the pH of water decreases, the solubility and speciation of metals are enhanced thus increasing their toxicity (Campbell and Stokes, 1985;Starodub et al, 1987;Rai et al, 1993). Arsenic, cadmium, copper, lead, and mercury are the most common heavy metal contaminants.…”

Section: Metalsmentioning

confidence: 99%

Water quality in the Okavango Delta

Mmualefe¹,

Torto²

2011

WSA

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The Okavango Delta ecosystem sustains a large number of plant and animal species as well as providing resources for the livelihood of the riparian human population. Despite changes in flow patterns, rainfall and other climatic conditions over the past decades, the system has responded well to maintain low salt-water balances through evapotranspiration and chemical precipitation processes. The electrical conductivity and total dissolved solids are generally low, with values less than 200 µS•cm -1 and averaging 40 mg•ℓ -1, respectively. The dissolved oxygen and dissolved organic carbon range from 1.8 to 8.8 and 5 to 15 mg•ℓ -1 , respectively, while pH ranges from 6.7 to 10.3. Total nitrogen and phosphorus are generally low with maximum concentrations of 1.7 and 1.6 mg•ℓ -1 , respectively, recorded downstream of the Delta. Even though most of these quality parameters are within limits for potable water, the Delta's ecosystem needs to be protected from anthropogenic activities. Past use of persistent organic pollutants requires monitoring of impacts of their residues on the plants and animal species within the ecosystem, in order to maintain its rich biodiversity. This review focuses on chemical quality data for water and sediments in the Okavango Delta published between 2000 and 2010. Despite the shortage of published data, it is hoped that this review will provide an overall picture of the status quo of the Delta's water and will set the direction for future monitoring efforts.

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“…Those released by phytoplankton and bacteria have been the most studied (McKnight and Morel, 1980;Jardim and Pearson, 1984;Mittelman and Geesey, 1985;Starodub et al, 1987;Xue and Sigg, 1990;Geesey et al, 1992;Leppard, 1995;Myklestad, 1995;Humble et al, 1997). The quantity and quality of extracellular products are dependent upon species, growth phase, physiological conditions and nutrient concentrations, making generalisations difficult.…”

Section: 434mentioning

confidence: 99%