Chemical Diversity and Antimicrobial Potential of Cultivable Fungi from Deep-Sea Sediments of the Gulf of Mexico

A collection of 29 cultivable fungal strains isolated from deep-sea sediments of the Gulf of Mexico were cultivated under the “one strain, many compounds” approach to explore their chemical diversity and antimicrobial potential. From the 87 extracts tested, over 50% showed antimicrobial activity, and the most active ones were those from cultures grown at 4 °C in darkness for 60 days (resembling deep-sea temperature). PCA analysis of the LC-MS data of all the extracts confirmed that culture temperature is the primary factor in the variation of the 4462 metabolite features, accounting for 21.3% of the variation. The bioactivity-guided and conventional chemical studies of selected fungal strains allowed the identification of several active and specialized metabolites. Finally, metabolomics analysis by GNPS molecular networking and manual dereplication revealed the biosynthetic potential of these species to produce interesting chemistry. This work uncovers the chemical and biological study of marine-derived fungal strains from deep-sea sediments of the Gulf of Mexico.     

Chemical composition of marine sediments in the Pacific Ocean from Sinaloa to Jalisco, Mexico

Marine sediments from Mexico’s West coast in the Pacific Ocean from Sinaloa to Jalisco were analyzed by energy-dispersive X-ray fluorescence technique. Ten sediment samples were collected in May, 2010 between 55.5 and 1264 m water depth with a Reinneck type box nucleate sampler. Sediments were dried and fractioned by granulometry. Their physical and chemical properties were determined in laboratory by standard methods, pH, and conductivity. Concentration and distribution of K, Ca, Ti Mn, Fe, Cu, Zn, Ga, Pb, Br and Sr were analyzed. In order to determine the status of the elements, enrichment factors were calculated. Total, organic carbon and CaCO₃ were also determined. Scanning electron microscopy and X-ray diffraction show predominant groups of compounds. As quality-control method, Certified Reference Material was both processed and analyzed at even conditions. Enrichment factors for K, Ca, Ti, Mn Fe, Cu, Zn, Ga, Ni, and Sr show they are conservative elements having concentrations in the range of unpolluted sites giving a base data line for the sampling zone In spite of moderately enrichment factors <100 μm size and bulk fractions, first Pb concentration fraction was similar to those found in not influenced by anthropogenic activities sites nearby Mazatlan Harbor. Bulk fraction concentration (52–133 μg g^?1) and enrichment factor show the influence of anthropogenic sources with values between lowest effect level and a third part of 250 μg g^?1value, which is considered to have severe effect levels for aquatic life.     

Assessment of trace metals contamination in estuarine sediments using a sequential extraction technique and principal component analysis

Fractionation of the metals Cd, Cr, Cu, Ni, Pb and Zn in sediments was performed for samples collected from eight locations in the Poxim river estuary of Sergipe State, northeast Brazil, using the 3-stage sequential extraction procedure proposed by the European Community Bureau of Reference (BCR). The extraction method was found to be satisfactory for analysis of certified reference material BCR-701, with recovery values ranging from 85% (Cu) to 117% (Cr). The detection limits obtained were 0.001 to 0.305 µg g^− 1. Zn exhibited greatest mobility and bioavailability, indicative of anthropogenic sources, while Cr was mainly found in the residual fraction and could be used as an indicator for the contribution from natural sources. Cd, Cu, Ni and Pb were associated with the oxidizable fraction, and Pb, Cr and Ni with the reducible fraction. Principal component analysis (PCA) clearly separated the metals into three groups: I (Zn); II (Pb); III (Cd, Cu, Cr and Ni). These groupings were mainly due to different distributions of the metals in the various fractions, in sediments from the different locations. Risk assessment code (RAC) analysis indicated that although the metals presented a moderate overall risk to the aquatic environment, nickel showed a low risk (RAC < 10%) at three sites, while zinc presented a high risk (RAC > 30%) at four other sites.     

Analysis of lanthanides and actinides in sea sediments from the Gulf of Tehuantepec

Seawater contains trace elements in solution, such as lanthanides and uranium, which can act as natural tracers when they flocculate to form the sediments of the seabed. Uranium is a special case because it is a radioactive element with isotopic ratio close to 1.14 (²³⁴U/²³⁸U) in sea water. Uranium is also present in all fractions of sediments, although the isotopic ratio in each fraction takes a specific value depending on its origin and surrounding environment. This work has been conducted in order to analyze lanthanides and uranium in a core of sea sediments. It is focused on separating the fractions forming the layers along the depth profile of the core sample so as to determine the ²³⁴U/²³⁸U activity ratios in fractions of organic matter, aquatic life skeletons and dissolved minerals. The Neutron Activation Analysis showed the presence of U, Lu, Hf, Eu, Ce and Yb ranging up to 50 ppm while alpha spectrometry gave a series of ²³⁴U/²³⁸U activity ratios which are discussed on the basis of statistical analysis.     

Sequential extraction of trace metals from sediments

With the aim of harmonizing the methodology associated with the trace metal partitioning in sediments, a group of European researchers proposed a three-step sequential extraction scheme using acetic acid, hydroxylamine hydrochloride and ammonium acetate as extracting agents. The metal content in each extract is mainly determined by AAS or ICP.In this paper, the validation of chromium determination in the extracts by AAS is described. The optimum instrumental conditions and the matrix effects of the different reagents used in the extraction scheme are studied for Cr(III) and Cr(VI) solutions by FAAS and ETAAS techniques. The effect of the concomitant species are also studied in the different extracts. The interfering effects are minimized by means of releaser agent for FAAS.The addition of 1% oxine is recommended for acetic acid and hydroxylamine extracts, whereas for step 3 the use of a releaser agent is not necessary. For ETAAS, the use of a calibration graph with pyrolytically-coated tubes gave satisfactory results.The procedure of analysis is applied to chromium partitioning in two sediments with certified total chromium content and to different sediments from Rio dos Sinos of Brazil.From the results obtained it is recommended to measure chromium contents in steps 1 and 2 by ETAAS and the content of step 3 by FAAS.     

Toxic and trace element analysis of surface sediments from the Gulf of Saros by INAA and XRF methods

Some surface sediment samples, collected from 53 sampling sites of the Saros Gulf, were analyzed quantitatively by radioisotope energy dispersive X-ray fluorescence (EDXRF) and instrumental neutron activation analysis (INAA). Results indicated some correlations between Rb and Sr (r = 0.64), Fe₂O₃ and MnO (r = 0.59), Th and La (r = 0.71), Th and Ce (r = 0.64), Th and Sm (r = 0.60), concentration pairs. U and Th results are found to be compatible with those given in the literature for marine sediments.     

Fractionation and speciation analysis of heavy metals in the Azov Sea bottom sediments

The fractionation and speciation analysis of heavy metals in bottom sediment samples from the Azov Sea were performed. Seven-step sequential extraction was used to extract element species differing in physicochemical mobility and biological availability. Special attention was paid to the study of ecologically valuable mobile fractions: exchangeable, acid-soluble, readily reducible, and readily oxidizable ones. It was shown that the total concentration of mobile copper, zinc, and lead species isolated in four extraction steps was higher than the MPCs for mobile species extractable with an ammonium acetate buffer solution (1.1–3.3 PMC), which points to the technogenic contamination of bottom sediments and their potential hazard to hydrobionts. For finely dispersed silt samples taken near the Kerch Strait, elevated concentrations of zinc and copper (up to 10 and 5 mg/kg, respectively) were found in the most mobile exchangeable fraction directly available to living organisms, which indicates the presence of an active contamination source in this water area. The binding of metals to mineral phases in samples of different lithological types was studied.     

Chemical analysis of the submicron binder phase in hard metals

Summary Chemical Analysis of the Submicron Binder Phase in Hard Metals The chemical analysis of the cobalt binder phase in sintered hard metals poses severe problems if performed by means of physical methods of surface analysis, such as SIMS, EMPA or AES. Compared with their limit of lateral resolution the average mean free path of the binder phase between the carbide particles, especially in micrograin hard metals, is less than 500 nm and thus too small. An electrochemical technique has been developed by which the carbide phase can be selectively etched away from the surface of a polished section, leaving the cobalt binder phase chemically and morphologically unchanged. The carbide-free cobalt binder phase can now be separated from the bulk hard metal using a technique similar to the well-known extraction replica technique commonly applied in transmission electron microscopy. The extracted binder phase can then be analyzed by X-ray fluorescence or other methods.     

Assessment of elemental contamination in the bottom sediments from a dam reservoir using a sequential extraction technique and chemometric analysis

The concentration of elements in sediments is an important aspect of the quality of water ecosystems. The element concentrations in bottom sediments from Goczalkowice Reservoir, Poland, were investigated to determine the levels, accumulation and distribution of elements; to understand the contamination and potential toxicity of elements; and to trace the possible source of pollution. Sediments were collected from 8 sampling points. The functional speciation, mobility and bioavailability of elements were evaluated by means of modified Tessier sequential extraction. The element contents were measured by optical emission spectrometry with inductively coupled plasma. The experimental results were analyzed using chemometric methods such as principal component analysis and cluster analysis to elucidate the metal distributions, correlations and associations. The highest concentrations of most elements were found at the center of the reservoir. The distribution of metals in the individual fractions was varied. To assess the extent of anthropogenic impact indices, contamination factor, degree of contamination, metal pollution index and risk assessment code were applied. The calculated factors showed the highest contamination factor and the ability of chromium to be released from sediments. The degree of contamination showed that the area is characterized by a very high contamination. Strontium and manganese showed high potential ecological risk for sediments.      

Pollution studies of trace elements in sediments from the Upper Saronikos Gulf,Greece

Seventeen trace elements (As, Ce, Co, Cr, Cs, Eu, Fe, Hg, Hf, La Lu, Rb, Sb, Sc, Sm, Yb and Zn) have been determined by Instrumental Neutron Activation Analysis in sediments from the upper Saronikos Gulf, Greece. It was found that the discharge of industrial and domestic wastes in the Keratsini and Elefsis bays of the upper Saronikos Gulf had led to elevated concentrations of all toxic and other trace elements determined over at least 100 km² of seafloor. Increases above natural level range from 2 fold for rare earths to 200 fold for arsenic.     

Radionuclides in redistributed sediments and ash from the Las Conchas fire in Northern New Mexico

The 2011 Las Conchas fire burned 632 km² of ponderosa pine forests and piñon–juniper woodlands in the Jemez Mountains in north central New Mexico. In the weeks following the fire, heavy rainfall caused extensive flooding and erosion of surface soil and ash from the affected areas. Samples from mud and ash flows were collected and analyzed for ¹³⁷Cs and Pu, which were originally deposited as global fallout during the era of atmospheric nuclear testing. The mean concentrations for ²³⁸Pu, ^239,240Pu and ¹³⁷Cs were 0.18 ± 0.05, 4.16 ± 1.95, and 111 ± 56 mBq/g, respectively. ^239,240Pu and ¹³⁷Cs are significantly elevated above non-fire affected regional background levels.     

Sequential extraction of U, Th, Ce, La and some heavy metals in sediments from Ortigas river, Spain

The extractable contents of U, Th, Ce, La, Cu, Cr, Ni and Zn in two sediment samples collected from the Ortigas river have been analysed using the three step sequential extraction procedure (SEP) described by BCR, Community Bureau of Reference (now Standards Measurements and Testing Programme) of the European Union. In order to perform a mass balance, a fourth step has been included, i.e. digestion of the residue from the third extraction step. ICP-AES was used for the determination of Cu, Cr, Ni, Zn, Th, Ce and La. Because of the inadequate sensitivity of ICP-AES for the analysis of uranium, ICP-MS was used for the determination of this element. Standard addition method was required, because of the matrix effects. Finally, SEP was applied to the Ortigas river sediments, showing that most of the elements were found mainly associated with the residual sediment fraction, except for uranium, which was found as an exchangeable species in approximately 60% of its total content. Recoveries of 86-108% have been obtained.     

High-performance liquid chromatography with sequential injection for online precolumn derivatization of some heavy metals

HPLC was coupled with sequential injection (SI) for simultaneous analyses of some heavy metals, including Co(II), Ni(II), Cu(II), and Fe(II). 2-(5-Nitro-2-pyridylazo)-5-[N-propyl-N-(3-sulfopropyl)amino]phenol (nitro-PAPS) was employed as a derivatizing reagent for sensitive spectrophotometric detection by online precolumn derivatization. The SI system offers an automated handling of sample and reagent, online precolumn derivatization, and propulsion of derivatives to the HPLC injection loop. The metal-nitro-PAPS complexes were separated on a C(18)-muBondapak column (3.9x300 mm(2)). Using the proposed SI-HPLC system, determination of four metal ions by means of nitro-PAPS complexes was achieved within 13 min in which the parallel of derivatization and separation were processed at the same time. Linear calibration graphs were obtained in the ranges of 0.005-0.250 mg/L for Cu(II), 0.007-1.000 mg/L for Co(II), 0.005-0.075 mg/L for Ni(II), and 0.005-0.100 mg/L for Fe(II). The system provides means for automation with good precision and minimizing error in solution handling with the RSD of less than 6%. The detection limits obtained were 2 microg/L for Cu(II) and Co(II), and 1 microg/L for Ni(II) and Fe(II). The method was successfully applied for the determination of metal ions in various samples, including milk powder for infant, mineral supplements, local wines, and drinking water.     

Sedimentation pattern and sediments bioavailability in a wastewater discharging area by sequential metal analysis

Atomic absorption spectrometry was applied to investigate sedimentation pattern and sediments bioavailable phase (BAP) at 41 sites of a wastewater discharging area. The position of sampling sites was confirmed by the aid of a global positioning system (GPS). Contaminants discharged from a large wastewater plant are dispersed to the inner bay and the coastal line rather than the outer bay and the center waterway. The fractional composition of sediment Zn in the discharging area accounted for the presence of exchangeable 239 mg/kg (35.1%)>reducible 163 mg/kg (24.0%)>carbonate 149 mg/kg (22.0%)>residual 98 mg/kg (14.4%)>organic 31 mg/kg (4.6%) in sediment layers of 0–2 cm. However, the order was changed in layers of 15–20 cm as residual>reducible>organic>carbonate>exchangeable. The most abundant fraction of sediment Cu and Fe was organic Cu and residual Fe, respectively. The content of BAP in sediments are quite different with respect to metal species and sediment layer analyzed. It is obvious that sequential metal analysis is a useful tool in understanding dispersion of sediments and sedimentation patterns.     

Chemical analysis of mixtures of some heavy metals by means of differential reaction rates of ligand substitution reactions

The simultaneous determination of some heavy metals in their mixtures is described. The method is based on the differential reaction rate of ligand substitution reactions involving ethyleneglycol bis(2-aminoethylether)N,N,N',N'-tetraacetic acid (EGTA) and 4-(2-pyridylazo)-resorcinol (PAR). Various combinations at the 10^-6M level of heavy metal ions such as manganese(II), iron(III), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), mercury(II) and lead(II) can be determined photometrically.     

Determination of trace metals in the River Ye?il?rmak sediments in Tokat, Turkey using sequential extraction procedure

Sequential extraction procedure (acid extractable, reducible, oxidizable, and residual) proposed by BCR was applied for the determination of trace metals in the River Yesilirmak sediments, Tokat, Turkey. The determination of trace metals in sediment samples was performed by flame atomic absorption spectrometry. The proposed method showed satisfactory recovery, detection limits and standard deviation for trace metals determination in sediment samples. Generally, most of the elements were found in the oxidizable and residual fractions. The total concentrations of trace metals analyzed were found to be (mg/kg) Cu: 37.9, Mn: 392.2, Zn: 126.2, Fe: 3726, and Pb: 29.6, respectively. Results obtained are in agreement with data reported in the literature.     

Assessment of metals and trace elements in sediments from Rio Grande Reservoir,Brazil, by neutron activation analysis

The Rio Grande Reservoir, Southeast of the São Paulo Metropolitan Area, supplies water for four counties (about 1.6 million people). It has been seriously affected by urban expansion due to chaotic urban occupation and improper use of the surrounding areas. In this study bottom sediment samples were collected during the dry season and rainy season. Four sampling points were defined and located at the mouth of the Rio Grande and Ribeirão Pires Rivers (points 1 and 2), in the middle of the reservoir (point 3) and near the catchment point of the water supply (point 4). Samples were submitted to instrumental neutron activation analysis and some metals, trace and rare earth elements were determined. The methodology validation according to precision and accuracy was carried out by reference material analyses. The results obtained were compared to earth crust values and also with results already published in the literature. The enrichment factor in relation to earth crust values using Sc as reference element was calculated and a strong enrichment was found for the elements As, Br, Sb, Th, U and Zn. A strong anthropogenic influence was observed for some elements, mainly in the points located in the entrance of the reservoir that receives domestic and industrial effluents from the rivers that reach the reservoir.     

Exploiting flow injection and sequential injection anodic stripping voltammetric systems for simultaneous determination of some metals

Flow injection (FI) and sequential injection (SI) systems with anodic stripping voltammetric detection have been exploited for simultaneous determination of some metals. A pre-plated mercury film on a glassy carbon disc electrode was used as a working electrode in both systems. The same film can be repeatedly applied for at least 50 analysis cycles, thus reducing the mercury consumption and waste. A single line FI voltammetric system using an acetate buffer as a carrier and an electrolyte solution was employed. An injected standard/sample zone was mixed with the buffer in a mixing coil before entering a flow cell. Metal ions were deposited on the working electrode by applying a potential of −1.1 V vs Ag/AgCl reference electrode. The stripping was performed by anodically scanning potential of working electrode to +0.25 V, resulting a voltammogram. Effects of acetate buffer concentration, flow rate and sample volume were investigated. Under the selected condition, detection limits of 1 μg l⁻¹ for Cd(II), 18 μg l⁻¹ for Cu(II), 2 μg l⁻¹ for Pb(II) and 17 μg l⁻¹ for Zn(II) with precisions of 2–5% (n=11) were obtained. The SI voltammetric system was similar to the FI system and using an acetate buffer as a carrier solution. The SI system was operated by a PC via in-house written software and employing an autotitrator as a syringe pump. Standard/sample was aspirated and the zone was then sent to a flow cell for measurement. Detection limits for Cd(II), Cu(II), Pb(II) and Zn(II) were 6, 3, 10 and 470 μg l⁻¹, respectively. Applications to water samples were demonstrated. A homemade UV-digester was used for removing organic matters in the wastewater samples prior to analysis by the proposed voltammetric systems.     

Analysis of heavy metals in road-deposited sediments

Road-deposited sediments were analysed for heavy metal concentrations at three different landuses (residential, industrial, commercial) in Queensland State, Australia. The sediments were collected using a domestic vacuum cleaner which was proven to be highly efficient in collecting sub-micron particles. Five particle sizes were analysed separately for eight heavy metal elements (Zn, Fe, Pb, Cd, Cu, Cr, Al and Mn). At all sites, the maximum concentration of the heavy metals occurred in the 0.45-75 μm particle size range, which conventional street cleaning services do not remove efficiently. Multicriteria decision making methods (MCDM), PROMETHEE and GAIA, were employed in the data analysis. PROMETHEE, a non-parametric ranking analysis procedure, was used to rank the metal contents of the sediments sampled at each site. The most polluted site and particle size range were the industrial site and the 0.45-75 μm range, respectively. Although the industrial site displayed the highest metal concentrations, the highest heavy metal loading coincided with the highest sediment load, which occurred at the commercial site. GAIA, a special form of principal component analysis, was applied to determine correlations between the heavy metals and particle size ranges and also to assess possible correlation with total organic carbon (TOC). The GAIA-planes revealed that irrespective of the site, most of the heavy metals are adsorbed to sediments below 150 μm. A weak correlation was found between Zn, Mn and TOC at the commercial site. This could lead to higher bioavailability of these metals through complexation reactions with the organic species in the sediments.