Minimizing Impacts of Maintenance Dredged Material Disposal in the Coastal Environment: A Habitat Approach

At present, coastal disposal of maintenance dredged material constitutes one of the most important problems in coastal zone management and in some coastal areas represents the major anthropogenic disturbance to the benthos. In this review we first propose, based on the classic literature, that macrofaunal communities typical of environmentally stressed habitats are more resilient than those of more environmentally stable habitats, and we outline the macrofaunal successional changes following a disturbance. Second, from a review and analysis of the published and unpublished literature on macrofaunal recovery following maintenance dredged material deposition in the coastal environment, we compare the successional sequences and recovery rates in euhaline and polyhaline systems. The review reveals that invertebrate recovery following dredged material disposal in relatively unstressed marine environments generally takes between 1 and 4 years, while in more naturally stressed areas, recovery is generally achieved within 9 months, although deeper polyhaline habitats can take up to 2 years to recover. Differences in recovery times are attributed to the number of successional stages required to regain the original community composition and that species typical of naturally unstressed assemblages do not possess life-history traits to allow rapid recolonization of disturbances. In the last section of this review, the management implications of these findings are discussed in terms of minimizing dredged material disposal impacts on fisheries resources. Since the natural disturbance regime appears to be very important in determining the response of a benthic community following dredged material disposal, it is recommended that when predicting the potential environmental impact of an operation, the nature of the physical environment in combination with the status (and role) of associated marine benthic communities should be considered.     

Mutual interactions in bioelectromagnetics

This paper discusses mutual interactions phenomena especially in the case of Transverse ElectroMagnetic (TEM) cell applications as an exposure system in technical and biomedical studies. In many publications is described problem of influence of an object upon the electromagnetic field (EMF) distribution inside a exposure system while inverse effect—influence of exposure system on tested object is overlooked. The problem plays primary role if a correlation between investigations carried out in an enclosure (e.g. TEM cell) and that in the free space is looked for.     

Computer-assisted navigation and the acquisition of route and survey knowledge

The incidental acquisition of spatial orientation knowledge when using a pedestrian navigation assistance system for wayfinding was compared to incidental learning during map-based wayfinding. First-time visitors to a real environment (a zoo) took a guided tour. In the navigation assistance conditions, users were provided with direction information and view-based pictures of the current intersection at each decision point, presented on a hand-held computer. In the map-based condition, participants derived route segments from a map (each segment comprising three or four intersections), and then walked the partial routes from memory. After walking, unexpected tests on route memory and survey knowledge were administered. Navigation assistance users showed good route knowledge and poor survey knowledge. In contrast, map users showed better survey knowledge and nearly perfect route knowledge. Variations of information presentation within navigation assistance conditions (auditory vs. visual direction command, additional presentation of allocentric spatial information) was not effective. Results are explained with an active encoding principle. Only information that is actually encoded, transformed, and/or memorized during the primary wayfinding activity, is incidentally learned. Since navigation assistance systems do not require users to encode, transform, and memorize spatial information, the spatial orientation knowledge of navigation assistance users is poor.     

Maternal care in house mice

Summary This paper analyzes the flexibility of maternal care in wild house mice (Mus domesticus) under different reproductive conditions in the laboratory. All maternal activities were both qualitatively and quantitatively analyzed over a period of 28 days after birth of a litter. The standard behavior of a lactating house mouse with 7–8 young can be described as follows: During days 1–16 the offspring fully depend on the mother for nutrition. Due to rapid growth of the litter, the energetic demands of lactation reach a peak for the female during days 13–16. During days 17–22, the weaning period, the young begin to eat solid food. This period is characterized by behaviors that indicate different interests of the mother and offspring, and thus the existence of a parent-offspring conflict sensu Trivers (1974). Resting alone and remaining far from the litter indicate the female's interest in avoiding the offspring's demands, which are expressed in frequent attempts to initiate sucking. There is no aggression towards the young during weaning. House mice are weaned at 23 days. The relationship between mother and young appears free of conflict after weaning. Nursing is replaced by resting with body contact, but the offspring do not try to suck. The following results suggest that during the weaning period the offspring do not get more milk than corresponds to the maternal optimum—despite their frequent sucking attempts:(a) When the mother is simultaneously lactating and pregnant, offspring are smaller at weaning than under standard conditions. (b) Small litters are weaned earlier than large ones. Despite a longer nursing period, offspring from large litters are lighter at weaning than those from small ones. (c) Under high energy demand, as after postpartum mating and with large litters, females wean their young at a body weight which corresponds to the earliest physiologically possible state of independence.Parity of the female has no effect on maternal activities, nor has the presence of the father. In the latter case, however, offspring are less often left alone and unprotected.Females seem to adjust their investment according to the body weight of the progeny by delaying or advancing the date of weaning (Table 2). This behavior allows the production of the largest possible number of offspring that can be raised to a minimal physiological threshold corresponding to a body weight of approximately 9 g. Such flexibility in parental care may enhance maternal fitness under different and unpredictable environmental conditions.     

Monitoring of odors emitted from stabilized dewatered sludge subjected to aging using proton transfer reaction–mass spectrometry

Environmental Science and Pollution Research - One of the potential emission sources of odorous compounds from wastewater treatment plants is sludge processing. The odorous compounds released from...     

Synergetic integration of laccase and versatile peroxidase with magnetic silica microspheres towards remediation of biorefinery wastewater

In this study, a tailor-made biocatalyst consisting of a co-immobilized lignolytic enzyme cascade on multi-functionalized magnetic silica microspheres (MSMS) was developed. Physical adsorption was the most promising strategy for the synthesis of individual immobilized laccase (IL), immobilized versatile peroxidase (IP), as well as co-immobilized laccase (Lac) and versatile peroxidase (VP) with an enzyme activity recovery of about 79, 93, 27, and 27.5%, respectively. Similarly, the biocatalytic load of 116, 183, 23.6, and 31 U/g was obtained for IL, IP, and co-immobilized Lac and VP, respectively. The co-immobilized enzyme system exhibited better pH stability than the free and individual immobilized system by retaining more than 100% residual activity at pH 7.0 after a 150-h incubation; whereas, the thermal stability and kinetics of the co-immobilized biocatalyst were not much improved. IL and IP could be recycled for 10 cycles after which they retained 31 and 44% of their initial activities. Co-immobilized Lac and VP were reused for ten consecutive cycles at the end of which Lac activity was depleted, and 37% of VP activity was left. Free enzymes, IL, IP, co-immobilized Lac, and VP were applied to biorefinery wastewater (BRW) in a batch study to investigate the transformation of phenolic contaminants over a period of 5 days. The major classes of phenolic constituents in terms of their order of removal in a Lac-VP system was phenol >2-chlorophenol > trichlorophenol > dichlorophenol > cresols > dimethylphenol >2 methyl- 4, 6-dinitrophenol > 4-nitrophenol > tetrachlorophenols > pentachlorophenol. The free enzymes and individually immobilized enzymes resulted in 80% dephenolization in 5 days. By contrast, the co-immobilized biocatalyst provided rapid dephenolization yielding the same 80% removal within 24 h and 96% removal of phenols in 60 h after which the system stabilized, which is the major advantage of the co-immobilized biocatalyst.

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Self-aeration in the rapidly- and gradually-varying flow regions of steep smooth and stepped spillways

In high-velocity chute flows, free-surface aeration is often observed. The phenomenon is called self-aeration or white waters. When the turbulent shear stresses next to the free-surface are large enough, air bubbles are entrained throughout the entire air–water column. A rapidly-varied flow region is observed immediately downstream of the inception point of free-surface aeration. An analytical solution of the air diffusion equation is proposed and the results compare well with new experimental data. Both experiments and theory indicate that the flow bulking spans over approximately 3–4 step cavities downstream of the inception point of free-surface aeration on a stepped chute. Further downstream the void fraction distributions follow closely earlier solutions of the air diffusion equation. The application of the diffusion equation solution to prototype and laboratory data shows air bubble diffusivities typically larger than the momentum transfer coefficient. The result highlights however a marked decrease in the ratio of air bubble diffusivity to eddy viscosity with increasing Reynolds number. The finding might indicate some limitation of laboratory investigations of air bubble diffusion process in self-aerated flows and of their extrapolation to full-scale prototype applications.