أجريت اختبارات السمية الحادة للمبيد الحشري كلوربيريفوس لتحديد متوسط التركيز القاتل النصفي LC50 خلال فترة تعرض 48 ساعة على ثلاثة أنواع من العوالق الحيوانية هي : Brachionus calyciflorus من الدوارات Rotifera، و الميزوسيكلوب Mesocyclops leuskarti من مجذافيات الأرجل Copepoda و الدافنيا Daphnia magna من متفرعات القرون Cladocera .
و قد تبين أن النوع Daphnia magna هو الأكثر حساسية للمبيد كلوربيريفوس حيث بلغت قيمة 48h-LC50 = 1.28 µg/L ، يليه النوع Mesocyclops leuskarti 48h-LC50 = 28 µg/L ، بينما لوحظ ضعف شديد في حساسية النوع Brachionus calyciflorus اتجاه المبيد 48h-LC50 = 910 µg/L .
و اعتماداً على قيم الوحدات السمية TU فقد تبين أن سمية المبيد كلوربيريفوس هي من المستوى الرابع = عالي السمية (TU= 78.30) بالنسبة لل Daphnia ، و من المستوى الثالث = حاد السمية (TU= 3.57) بالنسبة لل Mesocyclops ، بينما هو من المستوى الأول = عديم السمية (TU= 0.11) بالنسبة للدواري Brachionus .
و قد تبين أن كل زيادة في تركيز المبيد واحد ميكروغرام بالليتر تزيد معدل النفوق في أفراد جماعة النوع المدروس حوالي : Daphnia magna 68.79 % ، Mesocyclops leuskarti 0.22 % ، Brachionus calyciflorus 0.0468 %
و بالنتيجة يمكن أن نتوقع أن وصول المبيد إلى النظم البيئية المائية سوف يؤثر على المجتمع الحيوي في هذه النظم و على جملة العلاقات القائمة فيه و هذا بدوره من الممكن أن يكون سبباً لاختلال التوازن البيئي مع عواقب مبهمة من الصعب إدراك ابعادها.
Acute toxicity of the pesticide Chlorpyrifos tests were conducted to determine the
Lethal concentration LC50 during 48 hours exposure on three species of fresh water
Zooplankton: Brachionus calyciflorus ( Rotifera), Mesocyclops leuskarti (Copepoda) and
Daphnia magna ( Cladocera).
• It was found that the species Daphnia magna is the most sensitive to the pesticide
Chlorpyrifos as the value of 48h-LC50=1.28 μg/L, followed by the species Mesocyclops
leuskarti 48h-LC50=28 μg/L while it was observed severe lack of sensitivity of the species
Brachionus calyciflorus to the pesticide 48h-LC50=910 μg/L.
• Depending on the values of the units of toxicity TU has been shown that the
toxicity of the pesticide Chlorpyrifos is from the fourth level = highly toxic (TU = 78.30)
for Daphnia, and Level III = acute toxicity (TU = 3.57) for Mesocyclops, while it is the
first level = non toxic (TU = 0.11) for Brachionus.
• Each increase in the concentration of the pesticide 1.0μg/L lead to increase the
mortality rate in the species studied about: Daphnia magna ، % 68.79 Mesocyclops
leuskarti ، % 0.22 Brachionus calyciflorus % 0.0468
As a result, we can expect that the arrival of the pesticide to aquatic ecosystems will
affect the whole bio-community in these ecosystems and the inter their relationships,
which in turn could be the cause of the disruption of the ecological balance with vague
consequences that are difficult to understand its dimensions.
References used
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