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Use of toxicity identification evaluations to determine the pesticide mitigation effectiveness of on-farm vegetated treatment systems
2008
Hunt, John | Anderson, Brian | Phillips, Bryn | Tjeerdema, Ron | Largay, Bryan | Beretti, Melanie | Bern, Amanda
Evidence of ecological impacts from pesticide runoff has prompted installation of vegetated treatment systems (VTS) along the central coast of California, USA. During five surveys of two on-farm VTS ponds, 88% of inlet and outlet water samples were toxic to Ceriodaphnia dubia. Toxicity identification evaluations (TIEs) indicated water toxicity was caused by diazinon at VTS-1, and chlorpyrifos at VTS-2. Diazinon levels in VTS-1 were variable, but high pulse inflow concentrations were reduced through dilution. At VTS-2, chlorpyrifos concentrations averaged 52% lower at the VTS outlet than at the inlet. Water concentrations of most other pesticides averaged 20–90% lower at VTS outlets. All VTS sediment samples were toxic to amphipods (Hyalella azteca). Sediment TIEs indicated toxicity was caused by cypermethrin and lambda-cyhalothrin at VTS-1, and chlorpyrifos and permethrin at VTS-2. As with water, sediment concentrations were lower at VTS outlets, indicating substantial reductions in farm runoff pesticide concentrations. Toxicity identification evaluations identified key pesticides in agricultural runoff, and their concentrations were reduced by farmer-installed vegetated treatment systems.
اظهر المزيد [+] اقل [-]Cellular Distribution of Metals in a Liverwort and a Moss Transplanted to Two Streams of Differing Acidity
2008
Thiébaut, G. | Giamberini, L. | Ghanbaja, J.
To investigate the consequences of acidification and metal accumulation on the biology of aquatic bryophytes, the acid-tolerant liverwort Scapania undulata (L.) Dum. and the acid-sensitive moss Rhynchostegium riparioides (Hedw.) Cardot were transplanted from one stream to two other streams of differing acidity (pH 5.20 and 6.38). The bryophytes were collected in a circumneutral (pH 6.57) stream in the Vosges Mountains. Metal accumulation was semi-quantitatively measured in shoots by energy dispersive TEM X-ray spectroscopy (EDXS). After 1 month, the two species remained green without alteration signs. Although no marked ultrastructural damage was observed in either species, some cells seemed to be necrotic, with flattened chloroplasts, in R. riparioides. Lipid droplet accumulation was observed in some leaf cells of S.undulata when transplanted to the most acidic stream. Metal was mostly localised in the cell wall, and was only sometimes detected in small vacuoles. Under acidic conditions, R. riparioides showed the highest relative amount of Al and the lowest amount of Fe, whereas the acid-tolerant bryophyte species S. undulata contained more Fe and less Al. The capability to limit the uptake of metals into the cytoplasm varies according to the bryophyte species. This could be an explanation of the tolerance of S. undulata to acidification.
اظهر المزيد [+] اقل [-]Assessment of the Hyperaccumulating Lead Capacity of Salvinia minima Using Bioadsorption and Intracellular Accumulation Factors
2008
Sánchez-Galván, Gloria | Monroy, O. (Oscar) | Gómez, Jorge | Olguín, Eugenia J.
Salvinia minima has been reported as a cadmium and lead hyperaccumulator being the adsorption and intracellular accumulation the main uptake mechanisms. However, its physicochemical properties, the effect of metal concentration and the presence of organic and inorganic compounds on its hyperaccumulating capacity are still unknown. Furthermore, the specific adsorption and accumulation mechanisms occurring in the plant are not clear yet. Thus, based on a compartmentalization analysis, a bioadsorption (BAF) and an intracellular accumulation factor (IAF) were calculated in order to differentiate and quantify these two mechanisms. The use of kinetic models allowed predicting the specific type of uptake mechanisms involved. Healthy plants were exposed to five lead concentrations ranging from 0.80 ± 0.0 to 28.40 ± 0.22 mg Pb²⁺l⁻¹ in batch systems. A synthetic wastewater, amended with propionic acid and magnesium sulfate, and deionized water were used as media. The BAF and IAF contributed to gain an in-depth insight into the hyperaccumulating lead capacity of S. minima. It is clear that such capacity is mainly due to adsorption (BAF 780–1980) most likely due to its exceptional physico-chemical characteristics such as a very high surface area (264 m² g⁻¹) and a high content of carboxylic groups (0.95 mmol H⁺g⁻¹ dw). Chemisorption was predicted as the responsible mechanism according to the pseudo-second order adsorption model. Surprisingly, the ability of S. minima to accumulate the metal into the cells (IAF 57–1007) was not inhibited at concentrations as high as 28.40±0.22 mg Pb²⁺l⁻¹.
اظهر المزيد [+] اقل [-]Nitrogen Phytoremediation by Water Hyacinth (Eichhornia crassipes (Mart.) Solms)
2008
Fox, L. J. | Struik, P. C. | Appleton, B. L. | Rule, J. H.
The phytoremediation potential of water hyacinth, Eichhornia crassipes (Mart.) Solms, was examined in two independent studies under nitrogen (N) rates of 0, 40, 80, 100, 150, 200, and 300 ppm. A modified Hoagland solution was added to ponds containing water hyacinths which were rated and measured weekly for 4 weeks. The hyacinths accounted for 60–85% of the N removed from solution. Net productivity, as measured by dry matter gain, increased with an increase in N rate until 80 ppm. Above that level dry matter productivity was similar. Tissue N increased linearly with dry matter gain, but total nitrogen removal from the water increased exponentially with net dry matter gain or with an increase in canopy cover. The relation between total N in plant tissue and N removal from the water was similar for the two experiments.
اظهر المزيد [+] اقل [-]The degree of metals (Fe and Cu) accumulation in aquatic macrophytes in lakes near city Kragujevac [Serbia] | Stepen akumulacije metala (Fe i Cu) u nekim vodenim makrofitama jezera u okolini Kragujevca [Srbija]
2008
Brankovic, S., Prirodno-matematicki fakultet, Kragujevac (Serbia) | Pavlovic, D., Prirodno-matematicki fakultet, Kragujevac (Serbia) | Topuzovic, M., Prirodno-matematicki fakultet, Kragujevac (Serbia) | Milivojevic, J., Institut za strna zita, Kragujevac (Serbia)
The results of researches of the degree of metals (Fe and Cu) of accumulation in certain species aquatic macrophytes and their organs which sampled in three lakes near city Kragujevac are exposed in this study. The results show variability of the degree of accumation of Fe and Cu among species, their organs and researched localities, and capacity of some aquatic macrophytes species and their organs which accumulate high level of mentioned metals from aquatic environment. Results obtained in this reserches pointed important role of macrophytes vegetation in bioindication and phytoremediation, and ability for use for monitoring pollutants, in studies of quality aquatic ecosystems and their protection, repairing and revitalization.
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