Microscale Toxicity Identification Evaluation (TIE) for interstitial water of estuarine sediments affected by multiple sources of pollution

Estuaries in the world are affected by different contamination sources related to urbanisation and port/industrial activities. Identifying the substances responsible for the environmental toxicity in estuaries is challenging due to the multitude of stressors, both natural and anthropogenic. The Toxicity Identification and Evaluation (TIE) is a suitable way of determining causes of toxicity of sediments, but it poses difficulties since its application is labour intensive and time consuming. The aim of this study is to evaluate the diagnosis provided by a TIE based on microscale embryotoxicity tests with interstitial water (IW) to identify toxicants in estuarine sediments affected by multiple stressors. TIE showed toxicity due to different combinations of metals, apolar organic compounds, ammonia and sulphides, depending on the contamination source closest to the sampling station. The microscale TIE was able to discern different toxicants on sites subject to different contamination sources. There is good agreement between the results indicated in the TIE and the chemical analyses in whole sediment, although there are some disagreements, either due to the sensitivity of the test used, or due to the particularities of the use of interstitial water to assess the sediment toxicity. The improvement of TIE methods focused on identifying toxicants in multiple-stressed estuarine areas are crucial to discern contamination sources and subsidise management strategies.

     

Post-fire vegetation regrowth detection in the Deiva Marina region (Liguria-Italy) using Landsat TM and ETM+ data

Obtaining quantitative information about the recovery of fire-affected ecosystems is of utmost importance from the management and decision-making point of view. Nowadays the concern about natural environment protection and recovery is much greater than in the past. However, the resources and tools available for its management are still not sufficient. Thus, attention and precision is needed when decisions must be taken. Quantitative estimates on how the vegetation is recovering after a fire can be of help for evaluating the necessity of human intervention on the fire-affected ecosystem, and their importance will grow as the problem of forest fires, climate change and desertification increases.This article performs a comparison of methods to extract quantitative estimates of vegetation cover regrowth with Landsat TM and ETM+ data in an area that burned during the summer of 1998 in the Liguria region (Italy). In order to eliminate possible sources of error, a thorough pre-processing was carried out, including a careful geometric correction (reaching RMSE lower than 0.3 pixels), a topographic correction by means of a constrained Minnaert model and a combination of absolute and relative atmospheric correction methods. Pseudo Invariant Features (PIF) were identified by implementing an automated selection method based in temporal Principal Component Analysis (PCA), which has been called multi-Temporal n-Dimensional Principal Component Analysis (mT-nD-PCA).Spectral Mixture Analysis (SMA) was compared against quantitative vegetation indices which are based on well known traditional vegetation indices like Normalized Difference Vegetation Index (NDVI) and Modified Soil Adjusted Vegetation Index (MSAVI). Accuracy assessment was performed by regressing vegetation cover results obtained with each method against field data gathered during the fieldwork campaign carried out in the study area. Results obtained showed how vegetation cover fractions extracted from the NDVI based quantitative index were the most accurate, being superior to the rest of the techniques applied, including SMA.     

Selfing in <Emphasis Type=Italic>Parvulastra exigua</Emphasis>: an asterinid sea star with benthic development

Parvulastra exigua, a species that lacks a dispersive larva, is paradoxically one of the most widely distributed and abundant sea stars in Australia. The potential that self-fertilization and successful development of self-generated progeny might contribute to population maintenance in this species was investigated through induction of spawning in isolated individuals collected from five populations near Sydney, New South Wales (34°S, 151°E), during the spawning period (August–October 2010, 2011). Evidence of selfing differed significantly among the five populations but the level of selfing within individual egg masses did not. Overall, there was a mean of 8.9% fertilization in egg masses with embryos. Some clutches developed to the juvenile stage while others arrested development before hatching. The presence of miniscule testis tissue in gonads that appeared to be ovaries indicated that hermaphroditism may be more common in some populations than indicated by anatomy. Mixed mating (selfing + outcrossing), pseudocopulation during egg laying and developmental success of self-fertilized embryos may contribute to the ecological success of P. exigua. These might influence population genetic structure and would facilitate establishment of founder populations by a small number of migrants.     

Evaluation of surface water quality in aquatic bodies under the influence of uranium mining (MG, Brazil)

The quality of the water in a uranium-ore-mining area located in Caldas (Minas Gerais State, Brazil) and in a reservoir (Antas reservoir) that receives the neutralized acid solution leaching from the waste heaps generated by uranium mining was investigated. The samples were collected during four periods (October 2008, January, April and July 2009) from six sampling stations. Physical and chemical analyses were performed on the water samples, and the data obtained were compared with those of the Brazilian Environmental Standards and WHO standard. The water samples obtained from waste rock piles showed high uranium concentrations (5.62 mg L^?1), high manganese values (75 mg L^?1) and low average pH values (3.4). The evaluation of the water quality at the point considered the limit between the Ore Treatment Unit of the Brazilian Nuclear Industries and the environment (Consulta Creek) indicated contamination by fluoride, manganese, uranium and zinc. The Antas reservoir showed seasonal variations in water quality, with mean concentrations for fluoride (0.50 mg L^?1), sulfate (16 mg L^?1) and hardness (20 mg L^?1) which were low in January, evidencing the effect of rainwater flowing into the system. The concentrations for fluoride, sulfate and manganese were close or above to the limits established by current legislation at the point where the treated mining effluent was discharged and downstream from this point. This study demonstrated that the effluent discharged by the UTM affected the quality of the water in the Antas reservoir, and thus the treatments currently used for effluent need to be reviewed.     

Evaluation of surface water quality using an ecotoxicological approach: a case study of the Alqueva Reservoir (Portugal)

Background, aim, and scope  

Freshwater reservoirs can be impacted by several hazardous substances through inputs from agricultural activity, sewage discharges, and groundwater leaching and runoff. The water quality assessment is very important for implementation of the monitoring and remediation programs to minimize the risk promoted by hazardous substances in aquatic ecosystems. Evaluation of the degree of contamination of aquatic environments must not take in account only its chemical characterization but it must be complemented with biological assays, which determine potential toxic effects and allows an integrated evaluation of its effects in populations and aquatic ecosystem communities. The application of this type of strategy has clear advantages allowing a general evaluation of the effects from all the water components, including those due to unknown substances and synergic, antagonistic, or additive effects. There are only a few studies that reported ecotoxicological acute end points, for the assessment of surface water quality, and the relationship among toxicity results and the anthropogenic pollution sources and the seasonal period. The aim of this study was to assess the ecotoxicological characterization of the surface water from Alqueva reservoir (South of Portugal) and to evaluate the influence of anthropogenic sources of pollution and their seasonal variation in its toxicity. The construction of Alqueva reservoir was recently finished (2002) and, to our knowledge, an ecotoxicological assessment of its surface water has not been performed. Because of that, no information is available on the possible impact of pollutants on the biota. The surface water toxicity was assessed using acute and chronic bioassays. The results are to be used for developing a monitoring program, including biological methods.     

White tail markings are an indicator of quality and affect mate preference in rock sparrows

In birds, colourful and elaborate feathers are important traits in mate choice. Distinct tail white patches are present in many species of birds, but they remain little studied. Tail markings may indeed have a signal function because in many species males spread the tail offering a good view of these markings to females during courtship behaviour. Here, we investigated whether white tail spots in male rock sparrow, Petronia petronia, play a role in mate choice. In a free-living population of rock sparrows, we found a reduction in white tail spots size as the breeding season progressed due to abrasion, which was expected if tail spots act as a reliable quality indicator (i.e. a handicap). The same reduction was found under captive conditions, and males in worse condition (individuals that lost more weight) abraded a bigger part of white. This suggests that white tail markings are an indicator of male quality. In captivity, we measured female preference for males differing in white patch size in a mate choice experiment. The experimental reduction of the size of the males’ white spots resulted in a lower sexual interest by females. During courtship display, male rock sparrow shows a yellow breast patch (a carotenoid-based, sexually selected ornament) together with the white spots in the tail. The sizes of these two traits are positively correlated, but only the abraded white area in the tail correlates with a surrogate of individual quality (lost of weight). In conclusion, we can assert that the size of the white spots is preferred by female rock sparrows and it is a part of a multiple signal system.     

Evaluation of cetacean exposure to organotin compounds in Brazilian waters through hepatic total tin concentrations

In Brazil, there is no restriction to the use of organotins (OTs). Previous investigations have shown that hepatic ∑Sn in cetaceans is predominantly organic. Hepatic ∑Sn concentrations were determined by GFAAS in 67 cetaceans (13 species) that stranded on Rio de Janeiro (RJ) and Espirito Santo (ES) states. Concentrations (in ng/g wet wt.) of marine tucuxis (n = 20) from the highly contaminated Guanabara Bay (in RJ) varied from 1703 to 9638. Concentrations of three marine tucuxi foetuses and one newborn calf (all from Guanabara Bay) varied between 431 and 2107. Contrastingly, the maximum level among 19 oceanic dolphins was 346, and 15 out of these 19 specimens presented concentrations below detection limit. The levels of Sn in six marine tucuxis from a less contaminated area (ES) varied from below detection limit to 744. Comparing to the literature, coastal cetaceans from Brazil appear to be highly exposed to OTs.     

Isolation and characterization of a Pseudomonas aeruginosa from a virgin Brazilian Amazon region with potential to degrade atrazine

The use of pesticides to increase agricultural production can result in the contamination of the environment, causing changes in the genetic structure of organisms and in the loss of biodiversity. This practice is also inducing changes in the rainforest ecosystem. In this work, a Pseudomonas aeruginosa isolated from a preservation soil area of the Brazilian Amazon Forest, without usage of any pesticide, was evaluated for its potential to degrade atrazine. This isolate presented all responsible genes (atzA, atzB, atzC, atzD, atzE, and atzF) for atrazine mineralization and demonstrated capacity to use atrazine as a nitrogen source, having achieved a reduction of 44 % of the initial concentration of atrazine after 24 h. These results confirm gene dispersion and/or a possible contamination of the area with the herbicide, which reinforces global concern of the increase and intensive use of pesticides worldwide.     

Evaluation of the capacity of the cyanobacterium Microcystis novacekii to remove atrazine from a culture medium

The bioaccumulation of atrazine and its toxicity were evaluated for the cyanobacterium Microcystis novacekii. Cyanobacterial cultures were grown in WC culture medium with atrazine at 50, 250 and 500 μg L^?1. After 96 hours of exposure, 27.2% of the atrazine had been removed from the culture supernatant. Spontaneous degradation was found to be insignificant (< 9% at 500 μg L^?1), indicating a high efficiency for the bioaccumulation of atrazine by M. novacekii. There were no atrazine metabolites detected in the culture medium at any of the doses studied. The acute toxicity (EC₅₀) of atrazine to the cyanobacterium was 4.2 mg L^?1 at 96 hours demonstrating the potential for M. novacekii to tolerate high concentrations of this herbicide in fresh water environments. The ability of M. novacekii to remove atrazine combined with its tolerance of the pesticide toxicity showed in this study makes it a potential biological resource for the restoration of contaminated surface waters. These findings support continued studies of the role of M. novacekii in the bioremediation of fresh water environments polluted by atrazine.     

Application of Fenton, photo-Fenton, solar photo-Fenton, and UV/H2O2 to degradation of the antineoplastic agent mitoxantrone and toxicological evaluation

In the present study, selected advanced oxidation processes (AOPs)—namely, photo-Fenton (with Fe²⁺, Fe³⁺, and potassium ferrioxalate—FeOx—as iron sources), solar photo-Fenton, Fenton, and UV/H₂O₂—were investigated for degradation of the antineoplastic drug mitoxantrone (MTX), frequently used to treat metastatic breast cancer, skin cancer, and acute leukemia. The results showed that photo-Fenton processes employing Fe(III) and FeOx and the UV/H₂O₂ process were most efficient for mineralizing MTX, with 77, 82, and 90 % of total organic carbon removal, respectively. MTX probably forms a complex with Fe(III), as demonstrated by voltammetric and spectrophotometric measurements. Spectrophotometric titrations suggested that the complex has a 2:1 Fe³⁺:MTX stoichiometric ratio and a complexation constant (K) of 1.47 × 10⁴ M^–1, indicating high MTX affinity for Fe³⁺. Complexation partially inhibits the involvement of iron ions and hence the degradation of MTX during photo-Fenton. The UV/H₂O₂ process is usually slower than the photo-Fenton process, but, in this study, the UV/H₂O₂ process proved to be more efficient due to complexing of MTX with Fe(III). The drug exhibited no cytotoxicity against NIH/3T3 mouse embryonic fibroblast cells when oxidized by UV/H₂O₂ or by UV/H₂O₂/FeOx at the concentrations tested.