الغرر في العقود, دراسة فقهية مقارنة بين المذاهب الأربعة

Islam is a way of life and it does not allow betray of any kind to anyone especially in trade and business. Islam does not allow to buy or sell any type of commodity by any means in which there is a chance of betray, and along with it Islam also does not allow jugglery, betting, selling of item before purchasing and selling a commodity without having a possession. In Islamic Jurisprudence these conditional trade is known asGhararIt is then divided in two types of which the first type is prohibited by all school of thoughts and the other type is allowed by some school of thoughts

Acute Toxicity of Metals to the Fish Channa Marulius, Mystus Seenghala and Wallago Attu

The toxic effects of water-borne metals to the three carnivorous fish species viz. Channa marulius, Mystus seenghala and Wallago attu were determined in two phases i.e. (i) acute toxicity of individual metals and metals mixture to the fish and (ii) bioaccumulation of metals in the fish organs during acute toxicity exposures. The acute toxicities of individual metals viz. aluminium (Al), arsenic (As), cobalt (Co), nickel (Ni) and Al+As+Co+Ni mixture (MM), in terms of 96 h LC50 and lethal concentrations, to three length groups (50, 100 and 150mm) of C. marulius, M. seenghala and W. attu were determined at constant water temperature, pH and total hardness of 28oC, 8 and 250mgL- 1, respectively. The metals accumulation pattern in the fish organs viz. gills, liver, kidney, heart, gut, intestine, muscles, bones and skin of three fish species of 50, 100 and 150mm length groups was also determined at both 96 h LC50 and lethal concentrations of individual metals and MM, separately. Moreover, during each acute toxicity trial, the physico-chemical parameters viz. water temperature, pH, dissolved oxygen, carbondioxide, total hardness, total ammonia, electrical conductivity, calcium, magnesium, sodium and potassium of the test media, used for individual metals and MM, were also determined on 12 hourly basis. The tolerance limits of three carnivorous fish species for individual metals and metals mixture varied significantly at p<0.05. However, 150mm length groups of fish were significantly more tolerant to all the individual metals and MM toxicity than that of 100 and 50mm length groups. M. seenghala exhibited significantly (p<0.05) higher sensitivity to all the individual metals and MM, followed by W. attu and C. marulius. The overall sensitivity measured in terms of 96 h LC50 of all the three fish species towards individual metals and MM followed the order: MM>As>Al>Co>Ni while that of lethal concentrations was MM>As>Al>Ni>Co indicating that exposure of MM to the fish caused additive effects on the fish. The accumulation of metals in the body organs of three fish species varied significantly due to acute exposure of individual metals and MM. Three length groups of fish showed significant variability to amass metals in their body organs also. The ability of three length groups of fish to bioaccumulate metals in their bodies, under acute exposure of individual metals and MM, followed the order: 150mm ˃ 100mm ˃ 50mm. At acute toxicity exposures, the overall ability of three species of fish to accumulate metals in their body organs followed the order: C. marulius ˃ W. attu ˃ M. seenghala with significant differences. “Therefore, these fish species may act as bio-indicators of metals pollution in the natural freshwaters” At 96 h LC50 exposure, the overall accumulation of metals was significantly higher due to exposure of MM (254.44±78.40µgg-1) in all the three fish species, followed by that of Co (163.12±57.11µgg-1), Ni (162.53±66.14µgg-1), Al (128.98±54.16µgg-1) and As (46.16±13.52µgg-1). However, at 96 h lethal concentration, the overall accumulation of metals in the body organs of all the three species of fish followed the order: MM ˃ Ni ˃ Co ˃ Al ˃ As. At 96 h LC50 exposure, the overall pattern of Al and As accumulations in the organs of all the three species of fish followed the order: liver > kidney > gills > heart > gut > intestine > bones > skin > muscles with significant differences. However, Co accumulation in the fish varied significantly (p˂0.05) that followed the order: liver ˃ kidney ˃ heart ˃ gills ˃ intestine ˃ gut ˃ bones ˃ skin ˃ muscles. Ni accumulation was significantly higher in the fish liver, followed by that in kidney, heart, gills, gut, intestine, bones, skin and muscles. In general, the 96 h lethal concentration exposure caused significantly higher amassing of Al and Co in the fish liver, followed by that in kidney, gills, heart, gut, intestine, bones, skin and muscles. Fish kidney showed significantly maximum ability to concentrate As while muscles had significantly minimum amassing of As. The accumulation of Ni in the body organs of three fish species followed the order: liver > kidney > heart > gills > gut > intestine > bones > skin > muscles. However, the overall accumulation pattern of metals in the fish organs varied significantly as liver > kidney > gills > heart > gut > intestine > bones > skin > muscles. The toxicity of individual metals and MM to fish modified significantly due to dissolved oxygen, carbondioxide, total ammonia, calcium and magnesium of the test media. Both 96 h LC50 and lethal concentrations of fish showed significantly positive correlations with carbondioxide and total ammonia contents of the test media. Moreover, LC50 and lethal concentrations of individual metals and MM showed significantly direct relationships with the accumulation of metals in the body organs of fish demonstrating significantly direct impacts on each other. This also shows significantly variable susceptibility of three fish species towards individual metals and MM. The significant differences among three fish species for their tendency to amass various metals in their body organs showed species specificity that correlates with their sensitivity to individual metals and MM. At higher concentration of metallic ions, fish encountered stressful conditions that caused significantly more activity of the fish resulting into an excessive excretion of ammonia and carbondioxide. The stressful concentrations of metals/MM also resulted into significant decrease in the dissolved oxygen contents of the test media. These hypoxic conditions would have resulted into higher ventilation rate leading to enhanced water flow over the fish gills. This situation leads to more vigorous consumption of oxygen by the fish resulting into significant decline of dissolved oxygen contents of the test media at higher concentration of metallic ions as observed during present investigation.