Bioremediation of Mangroves Impacted by Petroleum

The majority of oil from oceanic oil spills (e.g. the recent accident in the Gulf of Mexico) converges on coastal ecosystems such as mangroves. Microorganisms are directly involved in biogeochemical cycles as key drivers of the degradation of many carbon sources, including petroleum hydrocarbons. When properly understood and managed, microorganisms provide a wide range of ecosystem services, such as bioremediation, and are a promising alternative for the recovery of impacted environments. Previous studies have been conducted with emphasis on developing and selecting strategies for bioremediation of mangroves, mostly in vitro, with few field applications described in the literature. Many factors can affect the success of bioremediation of oil in mangroves, including the presence and activity of the oil-degrading microorganisms in the sediment, availability and concentration of oil and nutrients, salinity, temperature and oil toxicity. More studies are needed to provide efficient bioremediation strategies to be applicable in large areas of mangroves impacted with oil. A major challenge to mangrove bioremediation is defining pollution levels and measuring recuperation of a mangrove. Typically, chemical parameters of pollution levels, such as polycyclic aromatic hydrocarbons (PAHs), are used but are extremely variable in field measurements. Therefore, meaningful mangrove monitoring strategies must be developed. This review will present the state of the art of bioremediation in oil-contaminated mangroves, new data about the use of different mangrove microcosms with and without tide simulation, the main factors that influence the success of bioremediation in mangroves and new prospects for the use of molecular tools to monitor the bioremediation process. We believe that in some environments, such as mangroves, bioremediation may be the most appropriate approach for cleanup. Because of the peculiarities and heterogeneity of these environments, which hinder the use of other physical and chemical analyses, we suggest that measuring plant recuperation should be considered with reduction in polycyclic aromatic hydrocarbons (PAHs). This is a crucial discussion because these key marine environments are threatened with worldwide disappearance. We highlight the need for and suggest new ways to conserve, protect and restore these environments.     

Heavy Metal Concentration Survey in Soils and Plants of the Les Malines Mining District (Southern France): Implications for Soil Restoration

Mining activities generate spoils and effluents with extremely high metal concentrations of heavy metals that might have adverse effects on ecosystems and human health. Therefore, information on soil and plant metal concentrations is needed to assess the severity of the pollution and develop a strategy for soil reclamation such as phytoremediation. Here, we studied soils and vegetation in three heavily contaminated sites with potential toxic metals and metalloids (Zn, Pb, Cd, As, TI) in the mining district of Les Malines in the Languedoc region (southern France). Extremely high concentrations were found at different places such as the Les Aviniéres tailing basins (up to 160,000 mg kg^?C1 Zn, 90,000 mg kg^?C1 Pb, 9,700 mg kg^?C1 of As and 245 mg kg^?C1 of Tl) near a former furnace. Metal contamination extended several kilometres away from the mine sites probably because of the transport of toxic mining residues by wind and water. Spontaneous vegetation growing on the three mine sites was highly diversified and included 116 plant species. The vegetation cover consisted of species also found in non-contaminated soils, some of which have been shown to be metal-tolerant ecotypes (Festuca arvernensis, Koeleria vallesiana and Armeria arenaria) and several Zn, Cd and Tl hyperaccumulators such as Anthyllis vulneraria, Thlaspi caerulescens, Iberis intermedia and Silene latifolia. This latter species was highlighted as a new thallium hyperaccumulator, accumulating nearly 1,500 mg kg^?C1. These species represent a patrimonial interest for their potential use for the phytoremediation of toxic metal-polluted areas.     

Geochemistry of Mercury Along a Soil Profile Compared to Other Elements and to the Parental Rock: Evidence of External Input

The vertical distribution of mercury along a weathering profile derived from a diabase was compared to the main geochemical and mineralogical characteristics of the soil and its parental rock. The sampling site was in a metropolitan area, nearby to an active quarry and relatively close to an industrial park. The samples of a 6-m-deep fresh exposure of the soil profile and also of fresh rock were collected during the dry season. Kaolinite, goethite, hematite, and residual primary minerals were identified in the soil samples. Typically, the concentrations of Hg in the soil are low. Whole samples contained between 1 (rock) and 37 ??g kg^?1 Hg, while the?<?63-??m soil fraction had up to 52 ??g kg^?1 Hg. The higher values of Hg corresponded to the upper layers of A (0?C10 cm) and B (200?C220 cm) soil horizons. Elemental gains and losses calculated against Zr resulted in the following order: Hg>>Pb?>?Zr?>?LREE?>?Nb?>?HREE?>?Al?>?Ti?>?Fe?>?Cr. Total organic carbon in soil samples varied between 0.2 and 5.1 g dm^?3, and correlation with Hg concentrations was moderate. The acid pH (4.2?C5.5) of the soil samples favors the sorption Hg species by predominant secondary phases like goethite and kaolinite. The Hg concentration of the rock is insufficient to explain the large enrichment of Hg along the soil profile, indicating that exogenic Hg, via atmospheric deposition, contributed to the measured Hg concentrations of the soil.     

Impact of Seasonal Fluctuations on the Sediment-Mercury, its Accumulation and Partitioning in Halimione portulacoides and Juncus maritimus Collected from Ria de Aveiro Coastal Lagoon (Portugal)

The availability of metals to plants is a complex function of numerous environmental factors. Many of these factors are interrelated, and vary seasonally and temporally. The current study intended to understand the influence of seasonal fluctuations and the vegetation of salt marsh plants (SMPs; Halimione portulacoides, Juncus maritimus) on sediment??s mercury (Hg) and its pH and redox potential (Eh), as well as their cumulative effect on the plant??s Hg-accumulation and Hg-partitioning potential. The area selected for the study was Laranjo Basin at Ria de Aveiro lagoon (Portugal) where a known Hg gradient was existed due to chlor-alkali plant discharge. Three sampling sites (L1, L2 and L3) were selected along a transect defined by the distance from the main Hg source. Samples were also collected from the Hg-free site (R). Irrespective of the plant vegetation, Hg in sediments gradually increased with a decreasing distance towards Hg-point source. The sediment colonised by J. maritimus showed more Hg concentration compared with H. portulacoides irrespective of the season. As a whole, J. maritimus accumulated Hg more than H. portulacoides at all the sampling sites, whereas in root, stem and leaf, the concentration was ranked as: L1 > L2 > L3 in both the plant species and was differentially influenced by seasonal changes. Moreover, root of both plants exhibited highest Hg concentration compared with stem and leaf. In addition, the leaf of H. portulacoides exhibited more Hg than leaves of J. maritimus. Bioaccumulation and translocation factors and dry weight were differentially influenced by seasonal changes. Taking together the results, the physico-chemical properties of sediment especially the sediment-Eh seems to be influnced by the type of plant vegetation and seasonal changes which in turn may have influenced the chemistry of sediments; thus, it enfluences the bioavalability of Hg and the Hg-retention capacity of both salt marsh sediments (SMSs) and SMPs (bioaccumulation factor). Moreover, SMSs vegetated by J. maritimus exhibited a stronger capacity for the retention and phytostabilization of Hg belowground (in sediments and/or roots) than those dominated by H. portulacoides. Conversely, those SMSs extensively vegetated by H. portulacoides are expected to translocate more Hg to aboveground parts, acting as a potential source of this metal to the marsh ecosystem. Therefore, J. maritimus and H. portulacoides may be used repectively for phytostabilization (in rhizosediments) and phytoextraction (by accumulation in aboveground plant tissue for subsequent plant removal).     

Tannin-Based Coagulants in the Depuration of Textile Wastewater Effluents: Elimination of Anthraquinonic Dyes

Two tannin-based coagulants have been tested on anthraquinonic dye elimination from aqueous solutions. Acquapol S5T, derived from Acacia mearnsii de Wild, and Silvafloc, derived from Schinopsis balansae, were found to be excellent agents in the destabilization of Alizarin Violet 3R dye and its elimination through coagulation from textile effluents. Both coagulants showed that high affinity to the dye molecule in a wide pH range and q values reaches significant levels (up to 0.5 mg mg^???1) with reasonable low coagulant doses. Dye?Ccoagulant system presented a consistent behavior if studied under the statistical perspective of a design of experiments, where initial dye concentration and coagulant dose were the operating variables. Finally, both coagulants seemed to follow a predictable theoretical model under the Langmuir hypothesis with an accurate adjusted r ² coefficient above 0.9.     

Studies in a Fixed-Bed Photocatalytic Reactor System Using Natural Materials for Degradation of a Dye Contaminant in Water

A fixed-bed photocatalytic reactor equipped with a cylindrical parabolic light concentrator was studied to remove organic dyes from water using natural volcanic ashes particles and nanostructured titania supported on volcanic ashes as photocatalytic materials. The influences of flow rate, photocatalyst and photocatalytic material adsorption capacity were studied. A fixed-bed photocatalytic reactor was designed and built in the laboratory; a methylene blue aqueous solution, used as model compound for dye contaminated water, was fed into the reactor. Methylene blue destruction efficiencies were monitored spectrophotometrically. Combined effects of dye adsorption and photodecomposition on photocatalyst were studied and compared by infrared spectroscopy.     

Lindane Biodegradation by Defined Consortia of Indigenous Streptomyces Strains

The current study aimed to compare lindane degradation by pure and mixed cultures of Streptomyces sp. Cell-free extracts were assayed for potentiating dechlorinase activity and, based on these results, consortia of two to six microorganisms were assayed for their growth on and degradation of lindane. Furthermore, the role of bacterial consortia of lindane-degrading strains was examined in lindane decontamination soil assays. Four actinobacteria, previously isolated from a pesticide-contaminated area, were selected because of their tolerance to lindane and their ability to use the pesticide as sole carbon source. These strains as well as Streptomyces sp. M7 and Streptomyces coelicolor A3 were used to study specific dechlorinase activity (SDA) and lindane removal in mixed cultures. Pure cultures presented SDA in the presence of 1.66 mg L^-1 lindane as carbon source. SDA was improved by certain mixed cultures until 12 times compared with pure cultures. Mixed cultures with two, three, and four strains showed maximum lindane removal of 46% to 68%, whereas combinations of five and six strains did not efficiently remove the pesticide from the culture medium. The Streptomyces sp. A2, A5, M7, and A11 consortium presented the lowest ratio between residual lindane concentration and SDA and could be a promising tool for lindane biodegradation.     

Mercury (Hg) Transport in a High Arctic River in Northeast Greenland

In a warming climate, mercury (Hg) pathways in the Arctic can be expected to be affected. The Hg transport from the high arctic Zackenberg River Basin was assessed in 2009 in order to describe and estimate the mercury transported from land to the marine environment. A total of 95 water samples were acquired and filtered (0.4 ??m pore size), and Hg concentrations were determined in both the filtered water and in the sediment. A range of other elements were also measured in the water samples. Hg concentrations in the filtered water were in general highest in the beginning of the season when the water came mainly from melted snow. THg concentrations in the sediment were in general relatively constant or slightly decreasing until mid-August, where after the concentrations increased. A principal component analysis separated the samples into spring, summer and autumn samples indicating seasonal characteristics of the patterns of element concentrations. The total amount of Hg in the sediment transported was estimated to 2.6 kg. Approximately 60% of the sediment-transported Hg occurred during a 24-h flood in the beginning of August caused by a glacial lake outburst flood. The total amount of transported dissolved Hg was estimated to 46 g, and 13% of this transport occurred during the 24-h flood. If it is assumed that the Hg transport by Zackenberg River is representative for the general glacial rivers in East Greenland, the total Hg transport into the North Atlantic from Greenland alone is approximately 4.6 tons year^?1 with an estimated annual freshwater discharge of ??440 km³.     

Dryland cropping systems influence the microbial biomass and enzyme activities in a semiarid sandy soil

Indicators of soil quality, such as microbial biomass C and N (MBC, MBN) and enzyme activities (EAs), involved in C, P, N, and S cycling, as affected by dryland cropping systems under conventional (ct) and no tillage (nt) practices were evaluated for 5?years. The soil is sandy loam with an average of 16.4% clay, 67.6% sand, and 0.65?g kg^?1 OM at 0?C10?cm. The crops evaluated were rotations of grain sorghum (Sorghum bicolor L.) or forage sorghum (also called haygrazer), cotton (Gossypium hirsutum), and winter rye (Secale cereale): grain sorghum?Ccotton (Sr_g?CCt), cotton?Cwinter rye?Csorghum (Ct?CRye?CSr_g), and forage sorghum?Cwinter rye (Sr_f?CRye). The tillage treatments did not affect soil MB and EAs of C cycling (i.e., ??-glucosidase, ??-glucosaminidase, ??-galactosidase), P cycling (alkaline phosphatase, phosphodiesterase), and S cycling (arylsulfatase)??except for separation due to tillage for Sr_f?CRye and Ct?CRye?CSr_g observed in PCA plots when all EAs were evaluated together. After 3?years, rotations with a winter cover crop history (Ct?CRye?CSr_g and Sr_f?CRye) enhanced soil MBN (up to 63%) and EAs (21-37%) compared to Sr_g?CCt. After 5?years, Sr_g?CCt and Ct?CRye?CSr_g showed similar soil MBC, MBN, EAs, total carbon (TC), and organic carbon (OC). A comparison of Sr_g?CCt plots with nearby continuous cotton (Ct?CCt) research plots in the same soil revealed that it took 5?years to detect higher TC (12%), MBC (38%), and EAs (32?C36%, depending on the enzyme) under Sr_g?CCt. The significant improvements in MB and EAs found, as affected by dryland cropping systems with a history of winter cover crops and/or higher biomass return crops than cotton, can represent changes in soil OM, nutrient cycling, and C sequestration for sandy soils in the semiarid Texas High Plains region. It is significant that these soil changes occurred despite summer crop failure (2003 and 2006) and lack of winter cover crops (2006) due to lack of precipitation in certain years.     

Antigenotoxicity and Antioxidant Activity of Acerola Fruit (Malpighia glabra L.) at Two Stages of Ripeness

Genotoxic and antigenotoxic effects of acerola fruit at two stages of ripeness were investigated using mice blood cells. The results show that no ripeness stage of acerola extracts presented any genotoxic potential to damage DNA (Comet assay) or cytotoxicity (MTT assay). When antigenotoxic activity was analyzed, unripe fruit presented higher DNA protection than ripe fruit (red color) extract. The antioxidant capacity of substances also showed that unripe samples inhibit the free radical DPPH more significantly than the ripe ones. The results about determination of compounds made using HPLC showed that unripe acerola presents higher levels of vitamin C as compared to ripe acerola. Thus, vitamin C and the complex mixture of nutrients of Malpighia glabra L., and especially its ripeness stages, influenced the interaction of the fruit extract with the DNA. Acerola is usually consumed when ripe (red fruit), although it is the green fruit (unripe) that has higher potential as beneficial to DNA, protecting it against oxidative stress.