Correction to: Toxicity prediction and assessment of an environmentally realistic pesticide mixture to Daphnia magna and Raphidocelis subcapitata.

Acknowledgements This work was supported by LEAF (UID/AGR/04129/2013) and CESAM (UID/AMB/50017/2013) from FCT/MEC through national funds, and the cofunding by FEDER (POCI-01-0145-FEDER-007638), within the PT2020 Partnership Agreement and Compete2020.

Toxicity prediction and assessment of an environmentally realistic pesticide mixture to Daphnia magna and Raphidocelis subcapitata.

In a regulatory perspective addressing the cumulative effect of co-occurring chemicals is the first and most important step in providing a more realistic hazard assessment of chemical cocktails to both man and environment. This study was conducted to show if joint effects on the immobilisation of the crustacean Daphnia magna and on the growth inhibition of algae Raphidocelis subcapitata follow additivity (concentration addition (CA) or independent action (IA) predictions) or if there is an interaction between chemicals in the organisms upon exposure to an environmentally realistic mixture of chlorpyrifos and terbuthylazine, with expected different molecular sites of action. A pattern of antagonism at lower doses and synergism at higher doses was found for acute immobility data, while no deviation from the additive conceptual models was observed in the algae inhibition test. Results in relation to the relevant set of regulatory acceptable concentrations (RACs) and environmental quality standards (EQSs) derived for individual chlorpyrifos and terbuthylazine were evaluated.

Pesticides in Portuguese surface and ground waters.

Pesticides used in Portuguese agricultural areas have been found in surface and ground waters. In the surface water collected in three river basins from 1983 to 1999, insecticides and herbicides were detected from the monitored pesticides, particularly atrazine, chlorfenvinphos (Z+E), alpha- and beta-endosulfan, lindane, molinate and simazine, reaching the maximum values, respectively, of 0.63, 31.6, 0.18 microg/L (alpha-endosulfan), 0.18 microg/L (beta-endosulfan), 0.24, 48 and 0.3 microg/L. In the ground water collected from the wells of seven agricultural areas from 1991 to 1998, several monitored herbicides were detected: alachlor, atrazine, metolachlor, metribuzine and simazine, reaching the maximum concentration values of 13, 30, 56, 1.4 and 0.4 microg/L, respectively. The herbicides more frequently detected were atrazine (64%), simazine (45%) and alachlor (25%). Other than these, the monitored pesticides can be present in Portuguese surface and ground waters. Therefore, to improve the analytical conditions, the use of multiresidue methods and automated techniques are desirable in future work.

Use of new microbiotests with Daphnia magna and Selenastrum capricornutum immobilized forms.

A preliminary assessment of toxicity to aquatic life of water from rice fields treated with pesticides, and particularly with the herbicides molinate and quinclorac, was performed from June to August 1996 in a rice paddy area integrated in a Natural Reserve. New rapid-screening microbiotests with Daphnia magna and Selenastrum capricornutum were used. Water samples were collected from: a water source for irrigating the rice fields, two rice plots, a drainage channel and the river in which the water is discharged. The results showed that while the water for irrigation was not toxic to D. magna, the samples collected from the river were very toxic causing 100% immobility in D. magna and substantial inhibition of Selenastrum growth. This, however, is due to the brackish nature of the river water. Water collected in the drainage channel of the rice fields were also found to be quite toxic. A greater effect was detected in samples from the rice plot treated with molinate than from that treated with quinclorac, suggesting that molinate treatment was more toxic to both species. The results indicate that the rapidity, simplicity and relatively low cost of the new microbiotests make them very practical for initial acute toxicity screening and offer an alternative to provide evidence for changes needed in agriculture practices for a better protection of the aquatic environment.