W. Lee Daniels

COMPARISON OF SOIL AND OTHER ENVIRONMENTAL CONDITIONS IN CONSTRUCTED AND ADJACENT PALUSTRINE REFERENCE WETLANDS

Wetlands are created to compensate for the loss of natural wetlands as a result of human landuse activities. How well these constructed wetlands mimic natural wetlands is in debate. The goal of this study was to compare soil and other environmental conditions within constructed and adjacent reference wetlands to assess the progress of the constructed wetlands towards a functional wetland. Three constructed wetlands in Virginia, USA, 4 to 7 years old, were paired with adjacent palustrine forested and scrub-shrub reference wetlands to examine differences in topography, hydrology, soil properties, and other environment conditions such as soil temperature and redox potential. Degree of microrelief was greater in reference wetlands than in the associated constructed wetlands. Seasonal fluctuations in water-table levels were similar in both wetland types. Two of the paired wetlands showed considerable differences (15 to 20 cm) in the depth to the water table. Redox potentials were similar in reference and constructed wetlands. Paired wetlands with water-table levels at or near the soil surface throughout the year showed similar soil temperatures. At the site where the summer water levels were 80 to 100 cm below the soil surface, summer temperatures were substantially higher in the poorly shaded, constructed wetland. At the two sites with high water-table levels throughout the year, percent clay and silt, levels of organic C and N, and cation exchange capacity were significantly greater (p <0.05) in the reference wetlands. At the drier site, only 3 of the 16 soil parameters compared were significantly different. In this limited study, observed differences in soil and other environmental conditions between paired wetlands suggest that constructed wetlands may not function in the same capacity as adjacent reference wetlands.

Prospects for enhancing carbon sequestration and reclamation of degraded lands with fossil-fuel combustion by-products

Concern for the potential global change consequences of increasing atmospheric CO has prompted interest in the 2 development of mechanisms to reduce or stabilize atmospheric CO .During the next several decades, a program 2 focused on terrestrial sequestration processes could make a significant contribution to abating CO increases.The 2 reclamation of degraded lands, such as mine-spoil sites, highway rights-of-way, and poorly managed lands, represents an opportunity to couple C sequestration with the use of fossil-fuel and energy by-products and other waste material, such as biosolids and organic wastes from human and animal sewage treatment facilities, to improve soil quality. Degraded lands are often characterized by acidic pH, low levels of key nutrients, poor soil structure, and limited moisture-retention capacity.Much is known about the methods to improve these soils, but the cost of implementation is often a limiting factor.However, the additional financial and environmental benefits of C sequestration may change the economics of land reclamation activities.The addition of energy-related by-products can address the adverse conditions of these degraded lands through a variety of mechanisms, such as enhancing plant growth and capturing of organic C in long-lived soil C pools.This review examines the use of fossil-fuel combustion by-products and organic amendments to enhance C sequestration and identifies the key gaps in information that still must be addressed before these methods can be implemented on an environmentally meaningful scale. 2002 Elsevier Ltd.All rights reserved.

Use of hydrogeomorphic concepts to design created wetlands in southeastern Virginia

Abstract Mitigation wetlands constructed in southeastern Virginia during the past decade have experienced problems with inappropriate water levels, excessive erosion and sedimentation, low levels of soil organic matter, overly compacted substrates, and sulfidic soils. Most of these problems can be recognized in the future with adequate planning that permits sufficient study of the geomorphic and hydrologic processes active at the mitigation site, and if greater attention is given to the history of geomorphic processes that created natural wetlands in that area. New procedures of assessing wetland functions that use the “hydrogeomorphic” (HGM) classification of wetlands require examination of both surface and subsurface processes. If these HGM concepts are expanded to include geomorphic evolution, they will greatly improve recent practices in the design and construction of mitigation wetlands.

Paper Mill Sludge Composting and Compost Utilization

Economically viable and environmentally acceptable methods to recycle organic wastes are needed by the pulp and paper industry. We assessed the potential for composting the Virginia Fibre Corporations (VFC) combined primary and secondary dewatered paper mill sludge (PMS) and evaluated the suitability of the finished product as a potting soil substitute. Composting treatments were: 1) PMS with no supplemental N (control), 2) PMS + 15 kg N/Mg PMS (dry weight), and 3) PMS + 30 kg N/Mg PMS (dry weight). Composting was conducted for 129 days and treatment effects were evaluated by windrow temperature trends. A container plant growth study employing various particle size fractions and proportions of the control PMS compost and a commercial potting medium (Promixtm) was conducted in a greenhouse to assess the capability of the compost to support growth of radish (Raphanus sativus L.), snap bean (Phaseolus vulgaris L.), marigold (Tagetes erecta L.), and green pepper (Capsicum sp.). Windrow temperatures were lowe...

Phytoavailability of cadmium in long-term biosolids-amended soils.

Agronomic use of biosolids has raised concern that plant availability of biosolids-Cd will increase with time after cessation of biosolids application. It has been demonstrated that chemical extractability of Cd is persistently decreased in biosolids-amended soils. This study was conducted to determine if Cd phytoavailability in long-term biosolids-amended soils was also persistently decreased. Paired control and biosolids-amended soils were collected from three experimental sites where large cumulative rates of biosolids were applied about 20 yr ago. The pH of all soils [in 0.01 mol L(-1) Ca(NO(3))(2)] was adjusted to 6.5 +/- 0.2. Increasing rates of Cd-nitrate (from 0 to 10.0 mg Cd kg(-1) soil) enriched in (111)Cd stable isotope were added to all soils, and Romaine lettuce (Lactuca sativa L. var. longifolia Lam.) was grown in pots to bioassay phytoavailable Cd. After harvest, Cd concentrations in shoots and labile pool of Cd (Cd(L)) in soils were determined. The relationship between added salt-Cd and Cd concentrations in lettuce shoots was linear for all soils tested. Ratios of (shoot Cd):(soil Cd) slopes were highest in the control soils. Biosolids amendment decreased (shoot Cd):(soil Cd) slopes to varied extent depending on biosolids source, properties, and application rate. The decrease in slope in comparison to the control was an indication of the lower phytoavailability of Cd in biosolids-amended soils. A significant negative correlation existed between Cd uptake slopes and soil organic matter, free and amorphous Fe and Al oxides, Bray-P, and soil and plant Zn. Biosolids-Cd was highly labile (%L 80-95) except for Fulton County soil (%L = 61).

Generating productive topsoil substitutes from hard rock overburden in the southern appalachians.

Natural soils on steeply sloping landscapes in the Appalachian coal fields of Virginia. West Virginia. Kentucky, and Tennessee are often thin, rocky, acidic and infertile, making the topsoiling of surface mined sites impractical in many cases. Topsoil substitutes composed of blasted rock fragments are commonly used in this region. The proper selection and placement of designated topsoil substitutes is therefore critical to long term reclamation success. These mine soil surfaces are not in equilibrium and with the surface environment, and it is quite difficult to diferentiate among dissolution, adsorption, desorption and precipitation reactions as these surfaces weather with time. Severe compaction limits the productivity of many otherwise suitable topsoil substitutes. A minimum non-compacted thickness of 1 m is desirable to insure long run mine soil productivity for a variety of post-mining land uses. Significant changes in the physical, chemical, and mineralogical properties of mine soils occur within one year after placement. Mine soils high in silt content often form hard vesicular surface crusts, particularly when left unvegetated. The long term survival of plant communities on these mine soils is dependent upon mine soil organic matter accumulation and N and P cycling. Little is currently known about N and P dynamics in these mine soils, but P-fixation is a profound problem in high Fe3- spoils. Revegetation practices that were designed to meet 2-year bond release requirements may not he sufficient to meet new 5-year release standards. Hard rock derived mine soils can often equal or exceed native topsoil in productivity and post mining land use potential.

MICROBIAL AND GEOCHEMICAL RESPONSES TO ORGANIC MATTER AMENDMENTS IN A CREATED WETLAND

Soil organic matter (OM) is an important feature of natural wetlands (NWs) often lacking in created wetlands (CWs). Some have suggested that OM amendments be used to accelerate development of edaphic conditions in CWs. Our objective was to investigate microbial and geochemical responses to compost amendments at a CW. Five levels of amendments were incorporated into drier and wetter zones of the CW to test two hypotheses: 1) microbial biomass carbon (MBC) and denitrification potential will increase with increasing levels of amendments; and 2) phosphorus (P) sorption will decrease with increasing levels of amendments. Regression indicated that pH, MBC, and P sorption had linear relationships, while bulk density (BD) had an exponential relationship with amendment level. Denitrification enzyme assay (DEA) had highest values at intermediate amendment levels. Analysis of variance indicated amendment effects for BD, MBC, DEA, and P sorption, and wetness effects for pH and MBC. Amendment levels between 60-180 Mg ha−1 were ideal for microbial development and denitrification, while not sacrificing P sorption, and would be more logistically and economically feasible than levels of 200–300 Mg ha−1. However, responses to amendments were complex and optimizing amendments for certain functions may detrimentally affect other functions.

Micromorphology and dissolution of quartz sand in some exceptionally ancient soils

Abstract Scanning electron microscopy (SEM) was used to study the effect of prolonged weathering on the micromorphology of quartz sand. Three soil chronosequences in the southeastern United States (Virginia), with weathering profiles ranging in age from ∼ 90 ka to ∼ 10 Ma, were studied. Detrital sand grains from soil B horizons show that dissolution features are crystallographically controlled and develop progressively over time from smaller to larger etch pits, then to an interconnected network of grooves and crevasses, and finally to bulk grain decomposition. SEM also shows that disintegrating quartzite clasts in the oldest gravelly soils have been preferentially leached of silica cement, possibly due to selective weathering along ‘dust lines’ and spalling-off of quartz overgrowths. Severely etched quartz, usually attributed to tropical weathering, is an unreliable paleoclimate indicator because similar features can form as a result of prolonged weathering under a temperate climate. However, the well-defined relationship between quartz micromorphology and duration of weathering suggests that SEM is a useful tool for soil correlation and geomorphic analysis.

Artifact weathering, anthropogenic microparticles and lead contamination in urban soils at former demolition sites, Detroit, Michigan

A chronological sequence of urban soils 3-92 years old was studied to determine the effects of time on morphogenesis, artifact weathering, and the geochemical partitioning of Pb. Key chronofunctions determined are an increase in ˆA horizon Development Index (defined herein based on soil color) and water-soluble Pb, and a decrease in pH and C/N, with increasing soil age. Key artifact weathering reactions are: 1) portlandite in mortar altered to calcite, 2) ferrite in wrought-iron altered to ferrihydrite and goethite, and 3) carbonaceous materials altered to water-soluble organic substances. Mortar and wrought-iron were found to be Pb-bearing, but weather to produce immobilizing agents. Hence, they are both a source and a sink for Pb. The origin and mobilization of water-soluble Pb is complex and probably includes microbial extracellular polymeric substances, biodegraded soil organic matter, and solubilized organic substances derived from carbonaceous anthropogenic microparticles (soot, char and coal-related wastes).

VEGETATION DYNAMICS IN RESPONSE TO ORGANIC MATTER LOADING RATES IN A CREATED FRESHWATER WETLAND IN SOUTHEASTERN VIRGINIA

Created wetlands are often limited in soil organic matter, a product that usually accumulates with long-term ecosystem succession. Although many studies have tested the effect of adding organic material to these systems, few have quantified the effect of various loadings of organic matter (OM) in created wetlands. The purpose of this study was to determine how vegetation composition, standing crop biomass, and woody vegetation development varied in a created freshwater wetland with respect to different loadings (0, 56, 112, 224, or 336 Mg ha−1) of a soil OM amendment. Soil C, N, and P were positively related to loading rate, as was soil surface elevation. Species richness, evenness, and diversity measurements, along with the Ellenberg Community Coefficient Similarity Index, suggested an overall similarity of plant assemblages regardless of loading rate. Standing crop biomass (580–790 g m−2) was not significantly correlated with OM loadings, but showed a significant curvilinear relationship with plot surface elevation. Woody vegetation development was correlated with OM loadings, plot elevation, and soil P, indicating a positive relationship with all three factors. An amendment loading of 112 Mg ha−1 provided the maximum benefit because it provided soil nutrient levels that were within the range of natural wetlands while also minimizing changes in soil surface elevation due to the added bulk material.