4 research outputs found
The Trophic status of Bidighinzu Reservoir (Sardinia) before and after the diversion of waste waters
The purpose of this paper was to assess the effect of the diversion of wastewater on the trophic status of Lake Bidighinzu, a hypertrophic
man-made lake in Northern Sardinia, used as a drinking water reservoir. There have been problems with potabilization
since the early years of the diversion operation, particularly in the summer-autumn period. Data available (August 1978, February
1979 and March 1985) before the reservoir (1987) were compared with those collected during a study carried out in the annual cycle
immediately after (1988-1989) and after some years (1994 and 1996-1997). The study examined the dynamics of temperature,
main nutrients (total phosphorus, nitrate and ammonia), chlorophyll-a and phytoplanktonic biomass. No particular variation in the
water nutrient availability emerged from the comparison between these two situations - especially for total phosphorus, whose annual
mean concentrations were similar in the two annual cycles (386 mg P m-3 in 1988-1989 and 305 mg P m-3 in 1996-1997). Chlorophyll-
a and biomass were high during each period of study (annual mean values were 17 mg m-3 and 3.7 mg l-1 in 1988-1989 and
11 mg m-3 and 4.6 mg l-1 in 1996-1997). However, peaks were never higher than values recorded in August 1978 (112 mg m-3 and
133 mg l-1) due to an extraordinary bloom of Ceratium hirundinella (O.F. Müller). Species composition of phytoplankton was typical
of highly trophic conditions and was frequently characterised by the presence of Cyanophyceae and Bacillariophyceae. Results demonstrated
that, ten years after construction of the by-pass, the lake had shown no improvement in its trophic status. This might depend on many factors, among which the most likely might be the non-use or partial use of the diversion system, which allows the
sewage to continue to flow into the lake and keep its trophic status almost unchanged
The trophic status of Bidighinzu Reservoir (Sardinia) before and after the diversion of waste waters
The purpose of this paper was to assess the effect of the diversion of wastewater on the trophic status of Lake Bidighinzu, a hypertrophic man-made lake in Northern Sardinia, used as a drinking water reservoir. There have been problems with potabilization since the early years of the diversion operation, particularly in the summer-autumn period. Data available (August 1978, February 1979 and March 1985) before the reservoir (1987) were compared with those collected during a study carried out in the annual cycle immediately after (1988-1989) and after some years (1994 and 1996-1997). The study examined the dynamics of temperature, main nutrients (total phosphorus, nitrate and ammonia), chlorophyll-a and phytoplanktonic biomass. No particular variation in the water nutrient availability emerged from the comparison between these two situations - especially for total phosphorus, whose annual mean concentrations were similar in the two annual cycles (386 mg P m-3 in 1988-1989 and 305 mg P m-3 in 1996-1997). Chlorophyll-a and biomass were high during each period of study (annual mean values were 17 mg m-3and 3.7 mg l-1 in 1988-1989 and 11 mg m-3and 4.6 mg l-1 in 1996-1997). However, peaks were never higher than values recorded in August 1978 (112 mg m-3and 133 mg l-1) due to an extraordinary bloom of Ceratium hirundinella (O.F. Müller). Species composition of phytoplankton was typical of highly trophic conditions and was frequently characterised by the presence of Cyanophyceae and Bacillariophyceae. Results demonstrated that, ten years after construction of the by-pass, the lake had shown no improvement in its trophic status. This might depend on many factors, among which the most likely might be the non-use or partial use of the diversion system, which allows the sewage to continue to flow into the lake and keep its trophic status almost unchanged
First report of <i>Cylindrospermopsis raciborskii</i> in Italy
Cylindrospermopsis raciborskii is a
freshwater cyanobacterium of tropical
origin, also found in temperate regions.
It can produce toxins like
cylindrospermopsin (CYN) and
saxitoxins (STX, NEO). In 2004, it was
detected in three Italian lakes (Albano
Lake, Trasimeno Lake and Cedrino
Lake). Two of the three examined cases
were toxic to a liquid chromatography
coupled with tandem spectrometry apparatus
(LC-MS/MS), and analysis
demonstrated the presence of
cylindrospermopsin (CYN).
Formerly C. raciborskii blooms
were detected in 1995 (Trasimeno
Lake), in 2002 (Albano Lake) and in
2003 (Cedrino Lake), but in those cases
no toxicity analysis were performed due
to the lack of a standard toxin
Cyanobacterial toxins in Italian freshwaters
This study focuses on the occurrence and distribution of cyanobacterial toxins from 1989 to 2006 in several Italian
lakes of different characteristics and human uses, the latter including drinking water abstraction and recreation.
Phytoplankton and LC/MS/MS toxin analyses were performed on surface water samples collected from 28 lakes. The
most widespread species associated with toxin production belonged to the genera Microcystis, Planktothrix and
Anabaena. Extracellular concentrations varied from non-detectable values up to 226.16 ng/mL for microcystins (sum of
all variants), to 126 ng/mL for total cylindrospermopsin, and to 100 mg/g (dry weight) for anatoxin-a.
The toxin concentrations in the lake waters did not always correlate with the cyanobacteria cell densities. This
implies a need for control studies including toxin detection in water together with microscopic cell evaluations, in order
to avoid possible toxin underestimates