Soil and plant characteristics as determining factors in site selection for surface coal mine reclamation

Four vegetative associations occur on surface mines located in Mercer County, Pennsylvania. Seventeen different species of grasses and legumes and 30 different species of trees and shrubs were evaluated for their ability to become established and control erosion on surface mines. The amount of organic matter and soil moisture are the principle factors regulating the establishment of vegetative cover on surface mines. Those species possessing a fibrous root system are better able to adapt for erosion control than tap rooted species. Likewise, shrubs such as bristley locust (Robina hispida) and Silver Bush or Autumn Olive (Elaeagnus umbellata) that will produce shoots when a root becomes exposed due to erosion are better adapted for erosion control than other species. The methods and species utilized during reclamation will determine, at least in part, the future use of the land and should establish conditions for natural succession to occur.This study was supported by funds from the National Geographical Society and the Office of Water Resources, U.S. Department of Interior.     

Shrub and tree establishment on coal spoils in northern High Plains — USA

Trickle irrigation, during establishment, increased survival two fold for seven species of shrubs and trees planted on coal mine spoil in the semiarid area of northeastern Wyoming, USA. Increased survival of irrigated plants persisted for five years after initiation of this study, which included two growing and winter seasons after cessation of irrigation. Species included green ash (Fraxinus pennsylvanica), Russian olive (Elaeagnus angustifolia), silver buffaloberry (Shepherdia argentea), Siberian peashrub (Caragana arborescens), American plum (Prunus americana), ponderosa pine (Pinus ponderosa), and Rocky Mountain juniper (Juniperus scopulorum).     

Stokes drift through corals

Motivated by shallow ocean waves propagating over coral reefs, we investigate the drift velocities due to surface wave motion in an effectively inviscid fluid that overlies a saturated porous bed of finite depth. Previous work in this area either neglects the large-scale flow between layers (Phillips in Flow and reactions in permeable rocks, Cambridge University Press, Cambridge, 1991) or only considers the drift above the porous layer (Monismith in Ann Rev Fluid Mech 39:37–55, 2007). Overcoming these limitations, we propose a model where flow is described by a velocity potential above the porous layer and by Darcy’s law in the porous bed, with derived matching conditions at the interface between the two layers. Both a horizontal and a novel vertical drift effect arise from the damping of the porous bed, which requires the use of a complex wavenumber k. This is in contrast to the purely horizontal second-order drift first derived by Stokes (Trans Camb Philos Soc 8:441–455, 1847) when working with solely a pure fluid layer. Our work provides a physical model for coral reefs in shallow seas, where fluid drift both above and within the reef is vitally important for maintaining a healthy reef ecosystem (Koehl et al. In: Proceedings of the 8th International Coral Reef Symposium, vol 2, pp 1087–1092, 1997; Monismith in Ann Rev Fluid Mech 39:37–55, 2007). We compare our model with field measurements by Koehl and Hadfield (J Mar Syst 49:75–88, 2004) and also explain the vertical drift effects as documented by Koehl et al. (Mar Ecol Prog Ser 335:1–18, 2007), who measured the exchange between a coral reef layer and the (relatively shallow) sea above.

     

The search for indigenous dune stabilizers: Germination requirements of selected South African species

The coastline of South Africa is characterized by extensive dune fields which are threatened by development, and thus the demand of stabilization of drift sand will increase. The non-invasive alien grass speciesAmmophila arenaria is at present the dominant sand stabilizer. Due to its foreign origin and invasiveness in North America its use was criticized and indigenous sand-binding species would be preferred. The germination requirements of the nativeArctotheca populifolia, Ipomoea pes-caprae. Myrica cordifolia andScaevola plumieri were investigated. The results showed that for all four species the total germination time and germination phase could be shortened and germination success (number of germinated seeds) improved. The different scarification and stratification treatments broke the dormancy ofI. pes-caprae, M. cordifolia andS. plumieri, whereas the seeds ofA. populifolia were not dormant. Seeds ofI. pes-caprae andM. cordifolia had induced an innate dormancy, respectively, whereas the type of dormancy in seeds ofS. plumieri dormancy processes remained unknown.     

Assessment of toxicity of two types of drill cuttings from a drilling rig on the Trinidad East coast using Metamysidopsis insularis

This study investigated the relative toxicity of water-based cuttings (WBC) and synthetic oil-based cuttings (SOBC) to the marine species, Metamysidopsis insularis. Results obtained indicate that SOBC (LC₅₀ 1.2 (0.85–1.6)%) was more toxic to M. insularis than WBC (LC₅₀ 9.9 (8.3–11.8)%), with similar metal contents in both types of cuttings. The elevated levels of metals found in the cuttings when compared to surficial sediments may be due to both drilling fluids, as well as the rock strata from which the cuttings were obtained. Furthermore, total petroleum hydrocarbon (TPH) analyses demonstrated significantly higher concentrations of TPH present in SOBC (14,680?±?1250?mg?kg^?1) compared to WBC (860?±?115?mg?kg^?1). This may also be due to the increased depth and hence oil bearing rock formations in the selected sampling area, along with the associated synthetic oil-based drilling fluid. These findings therefore supply evidence that drill cuttings after treatment prior to discharge are potentially toxic to marine organisms.     

Effect of rotational ambient,discharge and inflow density on the formation and evolution of a density-driven current over a steep slope

Environmental Fluid Mechanics - This numerical study investigates the evolution of constant-flux high density fluid introduced vertically to a rotational low-density ambient through a circular...     

Effects of anoxia and hypoxia on the dormancy and survival of subitaneous eggs of<Emphasis Type="Italic"> Acartia bifilosa</Emphasis> (Copepoda: Calanoida)

Subitaneous eggs of the copepod Acartia bifilosa were incubated at low oxygen concentrations and in anoxic conditions to study the induction of dormancy and the longevity of the resting eggs. Eggs were incubated in hypoxic conditions for 8 or 10 days, and also in anoxic conditions for 8–441 days. After the anoxic and hypoxic incubations, the unhatched eggs were subsequently incubated in normal oxygen conditions to reveal the viability of the eggs. Low oxygen concentrations (< 0.17 ml l^–1) induced dormancy in the eggs: they did not hatch at these concentrations in the hypox experiments but did hatch afterwards. Eggs survived well in anoxic conditions: after 10 months at 4°C, approximately 40% of the eggs still hatched, while some eggs survived in anoxic conditions for a year at 13°C, which is longer than hitherto reported for subitaneous eggs of any copepod species. Also, sediment that contained eggs of copepods was stored in the laboratory to reveal the long-term survival of the eggs. When incubated after 1.8 years storage, more than 40% of A. bifilosa eggs hatched. The study shows that subitaneous eggs may also be used as a survival strategy on seasonal time scales. This may partly explain why A. bifilosa does not produce diapause eggs in the present study area in the northern Baltic Sea.Communicated by M. Kühl, Helsingør     

Uptake of dissolved organics by marine bacteria as a function of fluid motion

A mass transfer analysis predicts that fluid motion can increase the assimilation of dissolved organics by attached compared to free-living microorganisms under certain conditions. To test this we examined the effect of advective flow and fluid shear on the uptake of model compounds (leucine and glucose) by natural assemblages of heterotrophic bacteria, collected from Roosevelt Inlet, Delaware Bay (USA), in 1989. We found that [³H]leucine uptake by cells held in fluid moving at 20 to 70 m d^–1 was eight times larger than uptake by cells at a velocity of 3 m d^–1. This effect was only observed at low leucine concentrations (ca. 1 nM), when uptake was likely not saturated. When we added leucine at concentrations expected to saturate leucine uptake (ca. 11 nM), fluid motion past cells did not affect uptake. Fluid flow past bacteria did not increase [³H]glucose uptake, and laminar shear rates of 0.5 to 2.1 s^–1 did not increase either glucose or leucine uptake by suspended bacteria. These results indicate that fluid motion increases bacterial uptake of certain lowmolecular-weight dissolved organics only when the microorganism exists in an advective flow field. As predicted from a mass transfer model, fluid shear rates in natural systems are too low to affect bacterial uptake of such compounds.     

Mucous sheet formation on poritid corals: An evaluation of coral mucus as a nutrient source on reefs

The production, release, and subsequent consumption of coral mucus on reefs has been portrayed as a potential pathway for the transfer of coral and zooxanthellae production to other reef organisms. However, reported mucus production rates and analyses of nutritional value vary widely. Poritid corals provide a test system to measure mucus production because they produce mucous sheets which can be collected quantitatively. Fluid mucus and mucous sheets were collected fromPorites astreoides, P. furcata, P. divaricata during 1986 and 1987 on reefs in the San Blas Islands, Panama, La Parguera, Puerto Rico and the Florida Keys, USA. Mucus samples were collected from Indo-pacific poritids (P. australiensis, P. lutea, P. lobata, andP. murrayensis) on the Great Barrier Reef during 1985. Biochemical analyses of the fluid mucous secretions, and the derivative mucous sheet, indicate that the mucus is primarily a carbohydrateprotein complex.Porites fluid mucus had a mean caloric content of 4.7 cal mg^–1 ash-free dry weight (AFDW), while mucous sheets contained 3.5 cal mg^–1 AFDW. Sixty-eight percent of the mucous sheet was ash, while fluid mucus was 22% ash. The high ash and low organic contents suggest that mucous sheets have a low nutritional value. C:N ratios varied (range 6.9 to 13.7 for fluid mucus, and 4.8 to 5.9 for mucous sheets), but were similar to typical C:N ratios for marine organisms. Bacterial numbers and chlorophyll a concentrations were higher on mucous sheets than in the surrounding water. Although bacteria aggregate on mucous sheets, bacteria accounted for less than 0.1% of the carbon and nitrogen content of the mucous sheet. Lower C:N ratios in aged mucus, i.e. mucous sheets versus fluid mucus, were attributed to a loss of carbon rather than an increase in nitrogen. Mucous sheet production accounts for a small proportion (< 2% gross photosynthesis) of published values for coral production. In the San Blas Islands, Panama,P. astreoides produced mucous sheets at a rate of 1.5 g C m^–2 y^–1 and 0.3 g N m^–2 y^–1.P. astreoides andP. furcata produced mucous sheets with a lunar periodicity and may provide approximately monthly pulses of carbon and nitrogen to the reef food-web. However, the low annual production rates suggest that mucous sheets make a small contribution to overall energy flow on coral reefs.     

Annual life cycle of Chattonella spp., causative flagellates of noxious red tides in the Inland Sea of Japan

Effects of storage temperature on the dormancy and maturation of dormant cells of Chattonella spp. were investigated by the extinction dilution method using sediment samples collected in 1984 after the blooming in Harima-Nada. Seasonality of germinability in fresh sediments was also studied in 1985. A storage period of more than 4 months with a low temperature (11°C) was essential for the maturation to induce the germination capacity of dormant cells. The optimal temperature for germination (22°C) had no effects on the maturation. Using fresh Suo-Nada sediments, a marked seasonality of germinability was confirmed. It was weak from autumn to early winter, then strengthened gradually up to a high level, which was maintained between spring and early summer, and again decreased rapidly during summer. The annual life cycle of Chattonella spp., including vetetative and dormant phases, was summarized as follows: (1) vegetative cells in early summer originate from germination of dormant cells in sediments; (2) they form overwintering dormant cells during the summer season; (3) dormant cells spend a period of spontaneous dormancy until next spring; (4) the duration of post dormancy, an enforced one due to low temperatures, follows until early summer. The life cycle of Chattonella spp. is therefore well adapted to the temperature regime in temperate seas such as the Seto Inland Sea of Japan.     

Lipids and fatty acids of the benthic marine harpacticoid copepod<Emphasis Type="Italic"> Heteropsyllus nunni</Emphasis> Coull during diapause: a contrast to pelagic copepods

Many free-living copepods produce and store lipids prior to entering diapause (long-term dormancy). Heteropsyllus nunni Coull is the only marine harpacticoid copepod known to undergo any form of diapause. This study presents the first information on the types of lipids and fatty acids produced for long-term diapause in this benthic species. Sexually immature adults of H. nunni undergo diapause within a pliable self-made cyst. Prior to entering diapause (which lasts 3–4 months), they produce and store large amounts of orange lipid. The lipids apparently are utilized during diapause. Although some residual lipids remain, chiefly around the gonads, after the copepods emerge from their cysts, the lipid stores are visibly reduced. Typically, the copepods mate and produce eggs within 48 h after diapause is terminated. Light level and confocal laser scanning microscopy revealed that the lipid stores are distributed throughout the body in numerous oil droplets and not as a single oil sac, as seen in many marine calanoid copepods prior to overwintering (winter diapause). Transmission electron microscopy showed lipid spheres within the gut epithelium and large droplets of lipids stored extracellularly. Confocal laser scanning microscopy of copepods in pre-diapause, during diapause (encysted), post-diapause (recently excysted), and in reproductive condition, revealed that lipid stores are reduced following diapause, but are not totally absent. Analysis of lipid classes showed that H. nunni store predominantly wax esters/sterol esters (83% of total lipids) during diapause. The predominant lipid is most likely wax esters, as sterol esters typically are found only in small amounts in copepods. Fatty acid (FA) profiles of the copepods in diapause showed 16:0 to be most abundant followed by 16:1n-7 and 18:0; other FA occurred at concentrations <10% of total FA. Three polyunsaturated fatty acids (PUFA), 20:5n-3, 18:2n-6 and 20:4n-6, were found at concentrations <2% of total FA. These PUFA are "essential fatty acids" in H. nunni, obtained through dietary sources. The lipid classes and fatty acids present in H. nunni during diapause are compared to those of other copepods, some in a state of diapause and others not. It appears that lipid class and FA profiles are indicative of genetic makeup, type of diet or amount of food consumed prior to dormancy. Some classic paradigms of lipids and their association with copepod diapause are re-evaluated.Communicated by P.W. Sammarco, Chauvin     

Comments on “turbulent velocity profile in fully-developed open channel flows”

In a recent paper published in this journal, Bonakdari et al. (Environ Fluid Mech 8:1–17, 2008) presented a new formulation of the vertical velocity profile in the central portion of steady fully developed turbulent open-channel flows which is based on an analysis of the Navier–Stokes equations. The predicted mean streamwise velocity profiles presented by the authors represent dip phenomenon (maximum velocity below the free surface). The discusser would like to point out some contradictions and an error in the main demonstration. This error appears in the right-hand side term of the main Eq. 22 (Environ Fluid Mech 8:1–17, 2008) in the parameter α. Our corrected demonstration shows that α is equal to and not to as obtained by the authors (Environ Fluid Mech 8:1–17, 2008). The values of α used by the authors are under-estimated by 1, this difference has a significant effect on velocities and therefore will involve a difference between measured and predicted velocity profiles. Finally, the assumption of at the free surface is in contradiction with predicted velocity profiles.     

On the role of the viscosity ratio on buoyant miscible jet flows

Environmental Fluid Mechanics - In this work, we perform a series of experiments to study a buoyant miscible jet flow wherein a heavy fluid is injected vertically downward into a more viscous light...     

Function of the shell spine in the predaceous rocky intertidal snail Acanthina spirata (Prosobranchia: Muricacea)

Feeding observations revealed that Acanthina spirata (Blainville, 1832) uses the shell spine in a ramming and prying motion, resulting in the fracturing and/or forcing open of opercular plates in the barnacles Balanus glandula (Darwin, 1854) and Chthamalus fissus (Darwin, 1854). Attacking barnacles by using the shell spine may represent a second widespread feeding mechanism (in addition to drilling) in muricacean gastropods. Specialization of the shell spine for attacking barnacles is advantageous over drilling within the context of an optimal foraging theory. Rockey intertidal field and laboratory experiments at Palos Verdes and Los Angeles, California, respectively, in 1981–1982 revealed, that snails with a shell spine have lower handling times and feed at a greater rate than spineless snails which drill their prey. Spine penetration of prey as opposed to drilling takes considerably less time than a tidal cycle. This is expected to increase the success rate for completion of feeding, since during tidal flux snails risk being dislodged. Plasticity in attack mechanisms allows A. spirata with broken spines to penetrate prey by drilling while undergoing spine repair. Differences exist in spine-feeding by A. spirata on B. glandula and C. fissus. The attack process takes more than twice as long when snails attack B. glandula versus C. fissus. However, there is no difference in the mean number of spine thrusts required to penetrate the opercular plates of the two species. When feeding on the larger barnacle B. glandula, A. spirata ingests significantly greater dry weight per unit handling time than with C. fissus.     

Turbulent structures of buoyant jet in cross-flow studied through large-eddy simulation

Environmental Fluid Mechanics - In the present paper we study buoyant (plume) and non-buoyant (jet) fluid injection in a neutrally stratified uniform cross-flow. Both cases are of practical...     

Effect of chronic exposure to drilling fluid XP-07 on gonad histology in Tilapia guineensis

Changes in Tilapia guineensis gonads exposed for 12 weeks to XP-07 at a concentration of 2.5, 1.25, 0.63, or 0.32% were investigated using a static renewal method. The histological changes noted in the gonads of the exposed fish were inhibition of maturation in oocytes or spermatogenesis. In contrast, the four stages of sperm or ova development were present in the control fish and spawning occurred. The increasing degeneration (artesia) of maturing egg resulted in complete absence of matured eggs in the female gonads of fish exposed to highest concentration (2.5%) of drilling fluid. The gonadal somatic index (GSI) values were recorded in a decreasing order towards the higher tested concentrations. The GSI values ranged from 3.11 to 1.47% in females and from 0.42 to 0.16% in males, whereas in control, it was 3.18% for females and 0.52% for males. Data showed that XP-07 exerted adverse effects on reproductive processes, which led to impairment in the reproductive success of T. guineensis.     

The recent 500th anniversary of Leonardo da Vinci’s death: a reminder of his contribution in the field of fluid mechanics

Environmental Fluid Mechanics - In this work, a summary of Leonardo da Vinci’s contribution in the field of fluid mechanics is reported. Some theoretical laws or fluid flows analyzed or drawn...     

Comparative survival of bay scallops in eelgrass and the introduced alga, Codium fragile, in a New York estuary

Eelgrass, Zostera marina, is generally regarded as the preferred habitat of bay scallops, but in some cases scallop populations have persisted or increased in areas lacking eelgrass. This suggests that some other substrate(s) may serve important ecological functions for bay scallops. One candidate is Codium fragile, a macroalgal species with which bay scallops are known to associate and in which we commonly find juvenile and adult bay scallops in eastern Long Island, New York. In this study, we examined whether survival of planted bay scallops differed in Codium, eelgrass, and Codium + eelgrass substrates at two sites during August and October of 2 years. Survival of tethered scallops and recoveries of live free-planted individuals varied with scallop size, planting season and year, but no differences were observed between the three substrates for a given scallop size and planting date. Crab (particularly Dyspanopeus sayi) and whelk predation were implicated as important causes of tethered scallop mortalities while emigration and removal by predators likely contributed to scallop losses. Densities of naturally recruited 0+ years scallops recovered by visual and suction dredge sampling were similar in the eelgrass and Codium substrates. While our results suggest that Codium may offer some degree of predation refuge for bay scallops, further work needs to weigh the potential disadvantages of this substrate (such as low DO levels, potential attachment and transport of scallops, and differences in current flow, food availability and sedimentation relative to eelgrass) to determine if Codium may serve as a valuable habitat for bay scallops throughout their lifespan.     

Numerical Simulation of Interaction of the Heavy Gas Cloud with the Atmospheric Surface Layer

The numerical time-dependent three-dimensional model [Kovalets, I.V. and Maderich, V.S.: 2001, Int. J. Fluid Mech. Res. 30, 410–429] of the heavy gas dispersion in the atmospheric boundary layer has been improved by parameterizing momentum and heat fluxes on the surface of Earth using Monin–Obukhov similarity theory. Three parameterizations of heat exchange with the surface of Earth were considered: (A) formula of Yaglom A.M. and Kader B.A. [1974, J. Fluid Mech. 62, 601–623] for forced convection, (B) interpolation formula for mixed convection and (C) similarity relationship for mixed convection [Kader, B.A. and Yaglom, A.M.: 1990, J. Fluid Mech. 212, 637–662]. Two case studies were considered. In the first study based on experiment of Zhu et al., J. Hazard Mater 62, 161–186], the interaction of an isothermal heavy gas plume with an atmospheric surface layer was simulated. It was found that stable stratification in the cloud essentially suppresses the turbulence in the plume, reducing the turbulent momentum flux by a factor of down to 1/5 in comparison with the undisturbed value. This reduction essentially influences velocities in the atmospheric boundary layer above the cloud, increasing the mean velocity by a factor of up to 1.3 in comparison with the undisturbed value. A simulation of cold heavy gas dispersion was carried out in the second case based on field experiment BURRO 8. It was shown that both forced and free convections under moderate wind speeds significantly influence the plume. The relative rms and bias errors of prediction the plume’s height were σ_H ≈ 30% and ɛ_H = − 10%, respectively, for parameterization B, while for A and C the errors were σ_H ≈ 80% and ɛ_H ≈ − 65%. It is therefore advised to use the simple parameterization B in dense gas dispersion models.     

Shallow fluid flow over an obstacle: higher-order non-hydrostatic modeling and breaking waves

Environmental Fluid Mechanics - The simulation of shallow flows over obstacles is an important problem in environmental fluid dynamics, including exchange flows over seabed sills, atmospheric flows...