Origin and Distribution of Suspended Organic Matter As Inferred From Carbon Isotope Composition in A Mediterranean Semi-Enclosed Marine System

Abstract

The origin and distribution of suspended organic matter, the trophic features and the stable carbon isotopic composition of particulate organic carbon (POC) were studied monthly in a Western Mediterranean semi-enclosed basin. Sampling stations were selected as a function of wind-exposure and the degree of vegetation cover and then compared with an adjacent unvegetated site. the predominant vegetation was seagrass (Posidonia oceanica and Cymodocea nodosa) and Caulerpa prolifera. Water samples were analyzed for total suspended matter (inorganic and organic fractions), photosynthetic pigments (chlorophyll-a and phaeopigments), dissolved organic carbon, particulate organic carbon and their isotopic composition. Temperature and salinity were also measured at the same sampling sites within range of Mediterranean limits. the suspended organic matter concentration was 1.77 ± 1.55 mg l^?1; the chlorophyll-a concentration was low (0.35 ± 0.24 μg l^?1); the disolved organic carbon concentration was 2,140 ± 2,010 μg l^?1; the particulate organic carbon concentration was 212 ± 106 μg l^?1 and the isotopic composition was 18.77 ± 2.51%_°. There were significant temporal differences except for phaeopigments, POC and its POC isotopic composition, and there were no spatial differences other than for δ¹³C. This picture highlighted a general seasonal trend and trophical features similar to adjacent sea.

Spatial differences in δ¹³C showed that the source of suspended organic matter was different between stations as that between sources and wind-hydrodynamic constraints. In     

The distribution,metabolism and toxicity of 14c-DDT in model aquarium tanks with fish and sediment simulating a tropical marine environment

Studies conducted on the distribution, fate and metabolism of DDT in a model ecosystem simulating a tropical marine environment of fish, Gobious nudiceps, Lethrinus harak, Gobious keinesis, Gobious nebulosis and white shrimp (Panaeus setiferus), show that DDT concentration in the water decreases rapidly within the first 24?h. Rapid accumulation of the pesticide in the biota also reaches a maximum level in 24?h before gradually declining. The bioaccumulation factors calculated for the fish species (G. keinesis) and white shrimp (P. Setiferus) were 270 and 351, respectively, after 24?h. There was a steady build up of DDT residues in the sediment during the first 24?h which continued to a maximum concentration of 6.66?ng/g in the seawater/fish/sediment ecosystem after 3 weeks and 5.27?ng/g in the seawater/shrimps/sediment ecosystem after 2.7 days. The depuration of the accumulated pesticide was slow with only 54% lost in G. nudiceps within 3 days of exposure in fresh sea water. By contrast, depuration was fast in the white shrimp, which lost 97% of the accumulated pesticide under the same conditions. DDT was found to be toxic to two of the fish species (G. nebulosis and L. harak) and to white shrimp, and the degree of toxicity was dependent on the particular species. The 24?h LC₅₀ at room temperature for the fish species G. nebulosis and white shrimp was found to be 0.011 and 0.116?mg/kg, respectively. These levels are comparable to the ones recorded for the temperate organisms. Degradation of DDT to its primary metabolites, DDE and DDD, was found in all the compartments of the ecosystem with DDE being the major metabolite in the fish, shrimps and sediment, while in seawater, DDD dominated as the major metabolite.     

Effect of white African mineral hair dye on the activities of phosphatases and malondialdehyde level in selected tissues of albino rats

The effect of white African mineral dye Yombofita (YF) on the activities of alkaline phosphatase (ALP), acid phosphatase (ACP) and malondialdehyde (MDA) levels in the skin, liver, kidney and serum of albino rats was investigated. The chemical analysis of the dye was first carried out using solubility test, pH determination and X-ray fluorescence (XRF) elemental analysis. Six different concentrations (0.05, 0.15, 0.25, 0.5, 0.75 and 1.00%) of the dye were prepared using hydrogen peroxide (30 volume) as solvent. A total of 80 albino rats (Rattus norvegicus) were used for the study. The rats were divided into 8 groups of 10 each and were maintained on commercial feed for the period of the experiment i.e. 30 days. In group 1, the control group, the animals were applied distilled water on their heads, whereas in group 2 the vehicle i.e. hydrogen peroxide was applied. In groups 3 to 8 various concentrations of YF (white) dye ranging from 0.05, 0.15, 0.25, 0.5, 0.75 to 1.00% was applied respectively. At the end of the experiment, blood samples were collected and portions of the selected tissues were excised for the determination of ALP and ACP activities. The MDA level was also determined in the skin of experimental animals. The results revealed a significant decrease (p?p?相似文献   

Fatty acid composition of marine macroalgae from the Black Sea and Dardanelles

The fatty acid (FA) composition was determined in 14 species of marine macroalgae belonging to the Chlorophyta, Phaeophyta and Rhodophyta, which were collected from ?ile in the Black Sea and Kepez in the Dardanelles. Generally, polyunsaturated FAs and monounsaturated FAs were major components (50–77%). Total saturated FAs ranged from 22% to 50%, with 16?:?0 as the most abundant saturate (32–38%). Two samples of Cystoseira barbata collected from a different station had some differences from each other in their contents of 18?:?2n-6 and 18?:?3n-3 and in the 18?:?2n-6/20?:?4n-6 ratios. Green algal species had a significantly higher proportion of unsaturated FAs and a significantly lower proportion of saturated FAs than the red and brown algae. The amount of n-3 FAs was significantly higher in Ulva rigita, Chaetomorpha linum, Enteromorpha linza and Gracilaria verrucosa (8.88, 6.44, 5.31 and 5.24, respectively).     

Analysis of the toxicity of glyphosate and Faena® using the freshwater invertebrates Daphnia magna and Lecane quadridentata

With the present contribution an evaluation of the toxicity of the pure herbicide glyphosate and its commercial formulation Faena® is reported using the cladoceran Daphnia magna Strauss and the rotifer Lecane quadridentata Ehrenberg. LC₅₀, EC₅₀, NOEC, and LOEC values for each toxicant and for both test organisms are obtained. Regarding acute toxicity, Faena was 11-fold more toxic to L. quadridentata than pure glyphosate and slightly more toxic to D. magna (1.7-fold). Inhibition of esterase activity in L. quadridentata by glyphosate was the most sensitive end-point; the EC₅₀ was 1500-fold smaller than the LC₅₀. The implications of these results and their comparison with established international and national limit values for glyphosate are discussed.     

Adult respiratory distress syndrome in human organophosphate poisoning cases

Adult respiratory distress syndrome (ARDS) is a clinical syndrome which occurs due to various direct or indirect noxious agents and pyhsical mechanisms. One of the etiological factors is ingested chemicals (e.g. paraquat, ethylene glycol). The organophosphorous (OP) insecticides are the most toxic and frequently encountered chemicals that produce poisoning in humans. Studies were undertaken to investigate whether OP insecticides may produce ARDS. Fifteen autopsy cases due to suicidal OP insecticide poisoning were investigated. Toxicological analyses were performed with a gas chromatography-nitrogen phosphorous detector (GC-NPD). Methamidophos, dimefox and dichlorvos were the detected OP. Lungs were examined macroscopically. Two cases showed features compatible with ARDS in which the only cause of death was OP poisoning. Due to the severity of ARDS it is important to assess insecticidal exposure in an attempt to enhance survival patterns following OP poisoning in patients in order to initiate therapy.     

Interaction of alcohol and kola nut on brain sodium pump activity in Wistar rats

The effect of interaction of alcohol and kola nut on sodium pump activity was studied in Wistar rats. Thirty Wistar rats were divided into six groups of five rats per group. Control received a placebo (4 mL of distilled water). Groups 2–6 were treated for a period of 21 days with 10% (v/v) alcohol, 50 mg caffeine/kg, 50 mg kola nut/kg, or a combination of 10% (v/v) alcohol + 50 mg kola nut/kg, or 10% (v/v) alcohol + 50 mg caffeine/kg, respectively. One day after the final exposure, brains were harvested and several biochemical parameters examined including activities of total ATPase, ouabain-insensitive ATPase, ouabain sensitive ATPase (Na⁺–K⁺-ATPase) and levels of nonenzymatic breakdown of ATP and inorganic phosphate (P_i) released. Results showed that the essential enzyme of the brain responsible for neuronal function, Na⁺–K⁺-ATPase, was inhibited by alcohol–kola nut co-administration relative to control, resulting in a decreased ATP production, ion transport and action potential, leading to loss of neuronal activities.     

An assessment of the air pollution data from two monitoring stations in Kuwait

This article assesses the air pollution data from two monitoring stations in Kuwait. The measurements cover major pollutants, i.e., CO, CO₂, methanated and non-methanated hydrocarbons, NO _x , SO₂, O₃, and particulate matter (PM10). The data also includes meteorological parameters, i.e., solar intensity, temperature, wind speed, and wind direction, and has been collected over a period 4 years, from 2001 to 2004. Data analysis includes the assessment of annual hourly averages and 1-h maxima. Typical pollutant concentration trends, similar to those previously reported for Kuwait and for other locations around the world, are observed except for particulate matter measurements, which have higher values because of proximity to the desert. Emissions of nitrogen oxides show a consistent increase over the years. This is caused by the increase in the number of motor vehicles and the expansion in power generation and industrial activities. The data collected is a subset of the air quality criteria, as defined by the US EPA (United States Environmental Protection Agency).