Competitive sorption of heavy metal by soils. Isotherms and fractional factorial experiments

Competing ions strongly affect heavy metal sorption onto the solid surfaces of soil. This study evaluated competitive sorption of Cd, Cu, Ni, Pb and Zn on three soils: Calcixerollic Xerochrept, Paralithic Xerorthent and Lithic Haplumbrept. Monometal and competitive sorption isotherms were obtained at 25 degrees C. The individual effect of ions on retention of the others was ascertained by a fractional factorial analysis design. Most of the sorption isotherms belonged to type L subtype 2 in the classification of Giles. In competitive sorption the initial linear part was shorter and the knee sharper when compared with monometal sorption isotherms. Parameters related to sorptive capacity, such as Point B, Langmuir monolayer and Freundlich distribution coefficient, were higher in monometal than in competitive sorption, and in basic soils than in acidic soil. Calcium desorbed at different points of the sorption isotherms indicated that cationic exchange with Ca was the main retention mechanism in calcareous soils. For Pb, the ratio Ca desorbed/Pb sorbed was close to one; for Cu, Ni and Zn the ratio ranged from 1.20 to 1.37, probably due to partial dissolution of calcium carbonates by hydrolytic processes during retention. On the other hand, Cd had a ratio around 0.6 reflecting another additional retention mechanism, probably surface complexation. Fractional factorial design confirmed that the presence of the cations investigated reduced the amount of the five metals retained, but the presence of Cu and Pb in the system depressed Ni, Cd and Zn sorption more than the inverse. Cation mobility was enhanced when equilibrium concentration increased and the effect was higher in Ca-saturated soils.     

Topical scientific and practical issues of wildland fire problem

Problem of wildfires has not been resolved anywhere in the world. Mere increase of technical power does not lead to desirable results. Forests of developed countries burn as actively as those in Africa or in Russia. The main reasons of wildfire problem are as follows: (1) Constant wandering of dry seasons over the planet causing outbreaks of wildfires. (2) Unpredicted self-development of ordinary wildfires into awful fire disasters. (3) Difficulties in delivery and use of heavy machines on hardly accessible territories. (4) Absence of a perfect technique for economic evaluation of how effectively the wildfire control system works. (5) Absence of the system of payments encouraging wildfire fighters. To solve the problem of wildfires in Russia it is necessary to: (1) Create the Russian wildfire behaviour and fire effects prediction system on the basis of the developed classification of vegetation fuels and methods of their mapping as well as maximum utilization of forest inventory information and Geographic Information System (GIS). (2) Elaborate a technique of proper wildfire monitoring including estimation of vegetation damage. (3) Improve daily rating of regional fire danger. (4) Improve fire-preventive arrangement of the territory covered by vegetation, the main goal being creation of favourable conditions for active fire management. (5) Choose the main direction in elaboration of fire-fighting means and methods taking into account their universality, simplicity, reliability, etc. (6) Elaborate an improved technique for estimation of economic effectiveness of the wildfire control system. (7) Develop international cooperation of scientists and professionals in fire management.     

<Emphasis Type="Italic">Octopus insularis</Emphasis> (Octopodidae), evidences of a specialized predator and a time-minimizing hunter

Shallow-water octopuses have been reported as major predators of motile species in benthonic marine communities, capturing their prey by different foraging techniques. This study assessed for the first time the feeding ecology, foraging behavior, and defensive strategy during foraging, including the use of body patterns, to construct a general octopus foraging strategy in a shallow water-reef system. Octopus insularis was studied in situ using visual observations and video recordings. The diet included at least 55 species of crustaceans (70%), bivalves (17.5%), and gastropods (12.5%); however, only four species accounted for half of the occurrences: the small crabs Pitho sp. (26.8%) and Mithrax forceps (23.9%), the bivalve Lima lima (5.3%), and the gastropod Pisania pusio (4.9%). Poke and crawl were most frequent foraging behaviors observed in the video recordings. The foraging behaviors were associated with environmental variables and octopus body size. The sequences of foraging behavior showed characteristics of a tactile saltatory searching predator, as well as a visual opportunist. Body patterns showed a relationship with foraging behavior, habitat variables, and octopus body size. Mottle was the most frequent pattern, especially during poke and crawl, in shallower depths. Dorsal light–ventral blue green was more frequent during swimming at mid-water, and Blotch was the normal pattern during web-over by large animals. The large proportion of two species of small crabs in den remains, the intense search for food during short hunting trips, and the intense use of cryptic body patterns during foraging trips, suggest that this species is a ‘time-minimizing’ forager instead of a ‘rate-maximizer’.     

Spatio-temporal variability in fatty acid trophic biomarkers in stomach contents and muscle of Iberian sardine (<Emphasis Type="Italic">Sardina pilchardus</Emphasis>) and its relationship with spawning

Temporal variation in the fatty acid (FA) composition of stomach contents of Iberian sardines was compared to the relative contribution to dietary carbon made by different prey types for fish from two areas off Portugal. The effect of the FA content of the diet on sardine muscle FA composition was also studied, aiming at (1) analysing if FA biomarkers can be used as a complementary technique for the study of sardine diet and (2) to relate spatial and temporal variations of prey FA content with sardine condition and reproduction. Significant spatial differences in the FA composition of sardine diet occurred with concentrations of n-3 polyunsaturated FA, namely eicosapentaenoic acid [EPA, 20:5n-3] and linolenic acid 18:3n-3, being significantly higher in the diet of sardines from the west coast, whilst the diet of sardines from the south coast was richer in monounsaturated fatty acids (MUFA), namely the carnivory biomarker oleic acid 18:1n-9. These results are in agreement with the higher contribution made by diatoms and dinoflagellates to the diet of sardines off the west coast. Spatial variation in sardine dietary FA was also detected in their muscle composition, specifically for EPA, and the eicosapentaenoic/docosahexaenoic acid and (n-3)/(n-6) ratios, which were higher in sardines from the west coast. No difference in FA composition was detected between sexes, and the seasonal variability in sardine total FA concentration was primarily related to the seasonality of spawning. Sardines accumulate high concentrations of FAs during the resting stage of reproduction when the feeding intensity is similar or lower to that observed during the spawning season. Additionally, sardines show a high selective retention of MUFA and polyunsaturated FA (PUFA) throughout the year except at the beginning of the spawning season, when these FAs are largely invested in the formation of the gonads. Therefore, temporal and regional differences of prey environments are strong enough to be reflected in fish body composition, namely on the accumulation of essential FAs, which can have a strong impact on reproduction success for this species.     

Organochlorine concentrations in franciscana dolphins, Pontoporia blainvillei, from Brazilian waters

Blubber samples were collected from ten franciscana dolphins either incidentally captured in fishing operations or stranded on São Paulo (SP) and Paraná (PR) states littoral, Southeastern and Southern Brazilian coast, respectively. Determination of PCB, DDT and HCB concentrations were performed by capillary gas chromatograph coupled to electron capture detector (ECD). ΣDDT, ΣPCB and HCB concentrations ranged from 264 ng g⁻¹ to 5811 ng g⁻¹ lipid, from 909 ng g⁻¹ to 5849 ng g⁻¹ lipid and from 10 ng g⁻¹ to 61 ng g⁻¹ lipid, respectively. Regarding DDTs, the distribution of the mean percentages decreased in the following order: p,p′-DDE > p,p′-DDD > p,p′-DDT. The ΣDDT/ΣPCB ratio varied between 0.27 and 0.42 in Northern and Central SP coast, while in Southern SP and PR coast the values were 1.6 and 1.9, respectively. Dissimilarities in ΣDDT/ΣPCB ratios point to different sources of organochlorine compounds to franciscana dolphins in the study area. Considering the endocrine disruptive action of organochlorine compounds, the concentrations found in franciscana dolphins from Brazilian waters may represent an additional obstacle to the conservation of this endangered cetacean species.     

Persistent organic pollutants,heavy metals and parasites in the glaucous gull (Larus hyperboreus) on Spitsbergen

The prediction of a higher parasite infection as a consequence of an impaired immune system with increasing persistent organic pollution (POP) and heavy metal levels were investigated in adult glaucous gull (Larus hyperboreus) from Svalbard. The levels of chlorinated pesticides, polychlorinated biphenyls (PCBs), toxaphenes and polybrominated diphenyl ethers (PBDEs) were measured in liver. Cupper, cadmium, lead, mercury, selenium and zinc were measured in kidney samples. An elevated ratio of PCB-118 was found, suggesting that local contamination from the settlement was detectable in the glaucous gull. Eight cestodes, four nematodes, two acanthocephalan and three trematode helminth species were found in the intestine. A positive correlation was found between cestode intensities and selenium levels and between acanthocephalan intensities and mercury levels. No correlation was found between parasite intensities and POP concentrations. It is concluded that the contaminant levels found in glaucous gulls do not cause immune suppression severe enough to affect parasite intensity.     

Evaluation and in situ assessment of photodegradation of polyaromatic hydrocarbons in semipermeable membrane devices deployed in ocean water

Semipermeable membrane devices (SPMDs) were deployed in water using four different methods: a typical SPMD cage with and without a mesh cover, a bowl chamber and without any protection. In addition to routinely used performance reference compounds (PRCs), perdeuterated dibenz[a,h]anthracene was added. Due to its high sampler to water partition coefficient no measurable clearance due to diffusion was expected during the deployment period, hence any observed loss could be attributed to photodegradation. The loss of PRCs was measured and SPMD-based water concentrations determined. Results showed that a typical SPMD deployment cage covered with mesh provided the best protection from photodegradation. Samplers which had undergone the highest photodegradation underestimated PAH water concentrations by up to a factor of 5 compared to the most protected SPMDs. This study demonstrates that the potential for photodegradation needs to be addressed when samplers are deployed in water of low turbidity.     

Solar-driven photocatalytic treatment as sustainable strategy to remove pesticide residues from leaching water

Environmental Science and Pollution Research - We have demonstrated the potential leaching of eight compounds, one insecticide (flonicamid) and seven fungicides (myclobutanil, penconazole,...