No abstract

No abstract

No abstract

The Galápagos archipelago is a well-suited model ecosystem for investigating soil evolution.Here, we study mineral transformations and pedogenesis of the volcanic soils of Galápagos in response to weathering duration (1.5 to 1070 ka) and climate (humid vs. dry). Our results show that soil pH, electrical conductivity, organic carbon content, cation exchange capacity (CEC), and water retention decreased while clay content and bulk density increased with soil age under humid climate. Andic properties were expressed in soils ≤4.3 ka, but disappeared relatively early in pedogenesis and were absent in soils ≥26 ka. The clay fraction of the young, andic soils (≤4.3 ka) was dominated by allophane and ferrihydrite. After 26 ka of pedogenesis, illitic-vermiculitic phases were predominant, and in the older soils (≥166 ka), kaolinite, hematite and gibbsite prevailed. The sequence of soil orders from the youngest to This article is protected by copyright. All rights reserved.the second oldest site was Histosol -Andisol -Alfisol (vermiculitic) -Alfisol (parasesquic) -Ultisol. The oldest soil of the humid chronosequence (1070 ka) met all diagnostic criteria for an Oxisol except for the required low CEC. The soils at two dry comparison sites were less developed with low clay contents and vitric materials at 26 ka (Entisol), and dominantly smectitic clay mineralogy and pronounced shrink-swell features at 813 ka (Vertisol). Our results highlight a rapid transition through the Andisol stage during early pedogenesis as well as strongly divergent pedogenic development in humid vs. dry zones of the Galápagos Islands, both of which have important bearings on soil functioning and ecosystem evolution on this unique archipelago.

[POTENTIAL ANTIOXIDANT ACTIVITY OF SECONDARY METABOLITES FROM ENDOPHYTE BACTERIA ON Moringa oleifera L LEAF] This research aims to know the similarities between secondary compound metabolites produced by endophyte bacterial on host leaves and from  Moringa oleifera L (kelor) leaves as well as determine the magnitude of antioxidant activity compounds of secondary metabolites produced by bacterial endophyte. Based on the results of the test compound is secondary metabolite in both samples, for secondary metabolite compounds in the extract of the leaves of M. oleifera L. contains identified steroid compounds, flavonoids, saponins, tannins and phenolic compounds, while for metabolites secondary bacterial endophyte undetectable on the existence of any secondary metabolite compounds.For testing of antioxidants on endophyte bacterial extracts of leaves of M. oleifera L is done using the DPPH method, performed on variations of the concentration of 200, 400, 600, 800, and 1000 ppm with Ascorbic acid as a comparison. The results of the test get an IC50 of M. oleifera L leaf extract at 243.67 ppm, and supernatan extract from endophyte bacterial at 492 ppm. The IC50 values showed antioxidant activity in secondary metabolite compounds derived from extracts of the leaves of M. oleifera L which has an extreme antioxidant category. The amount of antioxidant activity for secondary metabolite compound extracts of bacterial endophyte on leaves of M. oleifera L category is feeble, and to extract the supernatan activity is weak compared to the value of the antioxidant activity of Ascorbic acid.

[SYNTHESIS AND CHARACTERIZATION OF XEROGEL RESULTS OF COPRECIPITATION OF LONG BEACH BENGKULU BEACH].  This research aims to synthesize and characterization to  Xerogel which synthesizes from Pantai Panjang  sands Bengkulu. The method used for this study to synthesizes Xerogel is to use the coprecipitation method. Qualitative XRF test against raw sand  materials that were used show that the content of the element is the most significant element of Si. The first  stages of the synthesis of Xerogel is a purification of the sand sample..  Xerogel synthesis is carried out in two phases, namely the manufacture of aqueous solutions of Sodium Silicate and continued with the formation of a gel. The production of Sodium Silicate solution is done using the NaOH concentration at 5, 6 and 7 M.  Gel formation process is done by adding a solution of HCl 10 M into the solution of Sodium Silicate, followed by process of filtration, washing and drying in the oven. The results showed that the optimum conditions of synthesis of Xerogel   obtained  using 6 M NaOH  , with a yield obtained is amounting at 0.8%. The results of the test by XRD shows that the silica crystal structure  on Xerogel  are amorphous-shaped. SEM-EDS test results show that the acquired  Xerogel on research has a smooth texture and size is not homogeneous with the highest content of elements are the elements Si and O.  PSA test shows that particle size in Xerogel an average at 191.4 nm.

[CHARACTERIZATION OF THE  ADSORPTION FROM IRON METAL IONS ISOTHERM ON THE SOIL IN BENGKULU CITY] Level of micronutrient elements Fe takes part in determining the fertility rate of agricultural land. Continuous oxidation of Fe the soil will cause soil poisoning, due to the soil saturated in absorb of Fe. This research aims to determine the characteristics of the soil, adsorption and its ability in absorption isotherm on  Fe metal. Soil samples were taken from the farm in the city of Bengkulu. The characteristics of the soil tested, i.e., water content, pH, and soil type. Adsorption isotherm type is a determination as Langmuir or  Freundlich isotherm. Soil sample after it is dried and cleaned and then milled and sieved at 100 mesh sieve. Moisture content is measured by dried in an oven for 24 hours and the measurement of the difference between the initial and the final weight of the soil. Determination of soil pH is measured by the pH meter on the CaCl2, and soil type is determined by calculating the percentage of sand, silt, and clay from the soil. Maximum adsorption capacity is determined from Fe adsorption isotherm after getting the pH, the weight of adsorbent and optimum contact time. Adsorption Isotherm was determined by adsorption of aqueous Fe variation at the concentration of  2.5; 5; 10; 15; 20; and 25 ppm on optimum pH and weight, and stirred at an optimum contact time, then filtered and measured its absorbance with UV-Vis spectrophotometer. Results of research results in the form of moisture content average 23.5%, soil pH value at 5 and soil type, i.e., dusty clay with the dominant form of Isotherm adsorption is a Freundlich isotherm, and the capacity of soil in adsorbing of iron on this research obtained is amounting to 45.6.

This research aims to know the ability of land in a residential area of the city of Bengkulu in adsorbed Alkyl Benzene Sulphonate  (ABS) and Linear Alkyl Benzene Sulphonate (LAS). Soil samples were taken at five-point i.e. the backyard of Balai Buntar,   Fatmawati  Airport, Beringin Raya , Pematang Gubernur and Simpang Nakau  with a drill ground at a depth of 20 cm and cleaned from garbage impurity. Then the soil characterized include moisture content, pH, texture and the organic content  and ABS and ALS adsorbsition measured using UV-vis spectrophotometers att 222-223 nm wavelengths. In this research tested the influence of pH, pulp and optimum contact time contacts from soil sample at in ABS and ALS adsorbsition The adsorbtion pattern is known as the Freundlich and Langmuir parameters. Based on research, generally, it can be concluded that the land in the residential area of Bengkulu city has characteristic average water content – average 23%, pH average – average 5.35 and it's Turn dusty clay. The optimum condition from soil in adsorbs from Alkyl Benzene Sulphonate (ABS) occurs at pH 3, a mass of 1 g and 2 hours of contact time with the adsorption capacity of 0.874 mg/g, while for Linear Alkyl Benzene Sulphonate (LAS)  adsorption  the optimum soil conditions occur at pH 2, mass 0.5 g and 1-hour contact time with the adsorption capacity of 1.607 mg/g.  The pattern of soil adsorption against ABS tends to follow the Langmuir equation whereas against LAS tend to follow the Freundlich equation. Adsorpstion of soil samples in Bengkulu City against ABS belongs to low and adsorpstion against LAS belongs to very low