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This work examines polycyclic aromatic hydrocarbon (PAH) concentrations in yard trash at various stages of the yard trash management cycle of collection, stockpiling, grinding and screening into mulch, and composting. Total extractable PAH concentrations were measured in yard trash at various management stages from 10 locations in Florida. The concentrations of 16 PAH compounds in processed yard trash ranged from 0.38 to 14 mg kg-1. PAH concentrations were detected in vegetative material harvested from a residential neighborhood, but were below the United States Environmental Protection Agency residential regional screening levels (RSLs). PAH concentrations near or above the RSLs were common in both unprocessed and processed yard trash collected at waste management facilities. PAH concentrations were amongst the highest in newly ground yard trash samples and were amongst the lowest in composted yard trash samples. These findings are important because land application of some waste materials, such as construction and demolition debris fines and street sweepings, are sometimes limited due to PAH. If processed yard trash, which is commonly land applied in residential settings, possesses similar PAH concentrations, evaluation of current risk assessment practices for land-applied wastes may require further examination. [ABSTRACT FROM AUTHOR]

To better understand the environmental impact of lead (Pb) in shooting range soils, Pb levels in three berm soils were characterized via size distribution, total Pb concentration, water-soluble Pb, sequential extraction and X-ray diffraction (XRD). About 60% of the mid-berm soils of ranges-G and -O existed in grain sizes between 0.5 and 0.25 mm (medium sand) while range-L was most abundant in the 0.25 - 0.106 mm (fine sand) size fraction. All three range soils had the most accumulation of lead (60 - 70%) in the very coarse sand size (2.0 - 1.0 mm). In ranges-G and -L, the index shows a decreasing Pb enrichment with decreasing particle size, which may be a result of bullet fragmentation and abrasion in shooting range soils. Sequential extractions reveal that ranges-G and -L had the highest proportion of Pb bound to organic matter while range-O was dominated by the carbonate-bound fraction. However, a substantial proportion (one-third) of Pb in soil from the three shooting ranges was associated with carbonates. The XRD result revealed the dominance of carbonates in range-O soil, calcite in range-G soil and metallic lead in ranges-G and -O soil. The conversion of metallic lead to carbonates may be a mechanism for natural attenuation of lead in shooting range soils. Implications for remediation of shooting range soils are further discussed. [ABSTRACT FROM AUTHOR]

Purpose: Copper is a trace element of environmental concern. Repeated applications of Cu-containing fungicides have resulted in a large scale of Cu contamination in agricultural soils. However, limited information is available regarding Cu accumulation and availability in soils under citrus production in the Indian River Area, South Florida, which has received increasing amounts of Cu fungicides to control canker and other diseases. The purpose of this study was to investigate Cu transformation, availability, and mobility in soils as affected by external Cu loading and soil properties. Materials and methods: Soil samples ( n = 18) were collected from representative commercial citrus groves in the Indian River area. These samples were characterized to understand the accumulation, availability to plant, and leaching loss, as influenced by soil properties, agricultural practices, and Cu fungicide inputs. Results and discussion: Significant accumulation and increased availability and mobility of Cu occurred in the soils with increasing citrus production period. Soil acidification enhanced Cu leaching in soil profiles. Available Cu estimated by Mehlich-3 or NHOAc extraction was highly correlated with total recoverable Cu, whereas the relationship between CaCl-extractable Cu and total recoverable Cu was affected by soil pH, with a greater slope of the relationship curve at soil pH < 6.5. Vertical movement of Cu in a soil profile was more pronounced at pH < 6.5. A large portion of soil Cu was present as organically bound, ranging from 43% to 62%, which was significantly correlated with both recoverable Cu and Mehlich-3-extractable Cu ( P < 0.001). Conclusions: Significant accumulation of Cu occurred in citrus grove soils due to anthropogenic inputs, and the availability and mobility of Cu in the soils were related to Cu accumulation and soil pH. Copper migration from Cu-contaminated soils to the environment was reduced when soil pH was 6.5 or higher. [ABSTRACT FROM AUTHOR]

Arsenic contamination is of great environmental concern due to its toxic effects as a carcinogen. Knowledge of arsenic background concentrations is important for land application of wastes and for making remediation decisions. The soil clean-up target level for arsenic in Florida (0.8 and 3.7 mg kg−1 for residential and commercial areas, respectively) lies within the range of both background and analytical quantification limits. The objective of this study was to compare arsenic distribution in urban and non-urban areas of Florida. Approximately 440 urban and 448 non-urban Florida soil samples were compared. For urban areas, soil samples were collected from three land-use classes (residential, commercial and public land) in two cities, Gainesville and Miami. For the non-urban areas, samples were collected from relatively undisturbed non-inhabited areas. Arsenic concentrations varied greatly in Gainesville, ranging from 0.21 to approximately 660 mg kg−1 with a geometric mean (GM) of 0.40 mg kg−1, which were lower than Miami samples (ranging from 0.32 to 112 mg kg−1; GM=2.81 mg kg−1). Arsenic background concentrations in urban soils were significantly greater and showed greater variation than those from relatively undisturbed non-urban soils (GM=0.27 mg kg−1) in general. [Copyright &y& Elsevier]

Focuses on weathering of lead bullets and its effect on the environment at several outdoor shooting ranges in Florida. Analysis of soil, plant and water samples; Presence of hydrocerussite in the weathered crusts and berm soils in the shooting ranges with alkaline soil hydrogen-ion concentration; Observation of elevated total lead concentrations in bermudagrass and in surface water.

Investigates taxonomic and geographic distribution of total phosphorus (P) in Florida surface soils. Distribution characteristics of P concentration; Taxonomic distribution of total P concentrations in disturbed and undisturbed soils; Impact of anthropogenic input of total P concentrations in soils.

Background concentrations of soil arsenic have been used as an alternative soil cleanup criterion in many states in the U.S. This research addresses issues related to the interpretation of background concentrations of arsenic in near pristine soils in Florida. Total arsenic was measured in 448 taxonomic and geographic representative surface soil samples using USEPA Method 3052 (HCl-HNO 3 -HF, microwave digestion) and graphite furnace atomic absorption spectrophotometry analysis procedure. Values were log-normally distributed, with geometric mean and baseline concentration (defined as 95% of the expected range of background concentrations) providing the most satisfactory statistical results. An upper baseline concentration of 6.21 mg As/kg was estimated for undisturbed soils (n=267) compared to 7.63 mg As/kg for disturbed soils (n=181). Temporal trend of total soil arsenic concentrations from 1967 to 1989 paralleled decreased usage of arsenic in U.S. agriculture. Soil arsenic background concentrations were generally higher in south Florida than in north and central Florida, and associated with wet soils. Individual high arsenic sites were scattered throughout the state, but the most highly concentrated of these occurred in the Leon-Lee belt along the Ocala uplift district extending to the southwestern flatwoods district. Extrapolation of the data using a single arsenic value regardless of the taxonomic and geographical differences in soil arsenic distribution would underestimate potential arsenic contamination in upland soils. [ABSTRACT FROM AUTHOR]

Reports on issues discussed by a panel of academic, industry and regulatory scientists on the resolution of arsenic background concentrations in Florida. Anonymity regarding specific sample locations; Vertical sampling issues; Data evaluation; Censorship of data sets; Florida Legislature's order for the Florida Department of Environmental Protection to develop rules for site rehabilitation incorporating risk-based corrective action principles.

Compares the accuracy and precision of three aqua regia digestion methods in determining concentrations of different elements found in 20 Florida soils using the National Institute of Standards and Technology's standard reference materials. Variations in properties of soil samples; Spectrophotometric analysis of elemental concentration in the digestion solution; Disadvantage of conventional aqua regia digestion procedures.

Soil contamination in urban environment by trace metals is of public concerns. For better risk assessment, it is important to determine their background concentrations in urban soils. For this study, we determined the background concentrations of 9 trace metals including As, Ba, Cd, Co, Cu, Ni, Pb, Se, and Zn in 214 urban soils in Florida from two large cities (Orlando and Tampa) and 4 small cities (Clay County, Ocala, Pensacola and West Palm Beach). The objectives were to determine: 1) total concentrations of trace metals in urban soils in cities of different size; 2) compare background concentrations to Florida Soil Cleanup Target Levels (FSCTLs); and 3) determine their distribution and variability in urban soils via multivariate statistical analysis. Elemental concentrations in urban soils were variable, with Pb being the highest in 5 cities (165–552 mg kg−1) and Zn being the highest concentration in Tampa (1,000 mg kg−1). Besides, the As and Pb concentrations in some soils exceeded the FSCTL for residential sites at 2.1 mg kg−1 As and 400 mg kg−1 Pb. Among the cities, Clay County and Orlando had the lowest concentrations for most elements, with Cd, Co, and As being the lowest while Ba, Pb and Zn being the highest. Among all values, geometric means were the lowest while 95th percentile was the highest for all metals. Most 95th percentile values were 2–3 folds higher than the GM data, with Pb presenting the greatest difference, being 4 times greater than GM value (58.9 vs. 13.6 mg kg−1). Still they were lower than FSCTL, with As exceeding FSCTL for residential sites at 2.1 mg kg−1. In addition, the linear discriminate analysis showed distinct separation among the cities: Ocala (Ba & Ni) and Pensacola (As & Pb) were distinctly different from each other and from other cities with higher metal concentrations. The large variations among elemental concentrations showed the importance to establish proper background concentrations of trace metals in urban soils. Image 1 • Background concentrations of 9 trace elements in 214 urban soils were determined. • Arithmetic and geometric mean, 95th percentile and upper confidence level were calculated. • Regardless city size, human activities had similar impacts on elemental concentrations. • As, Ba, Cr and Pb levels exceeded Florida Soil Cleanup Target Levels for residential sites. • Among all values, GM was the lowest while 95th percentile was the highest. Large concentration variations showed the importance to establish proper background concentrations of trace metals in urban soils. [ABSTRACT FROM AUTHOR]

Announces the discovery that the fern Pteris vittata (brake fern) is extremely efficient in extracting arsenic from soils and translocating it into its above-ground biomass. Importance of its role as an arsenic hyperaccumulator, and as the first fern found to function as a hyperaccumulator; Study of brake fern growing on a site in central Florida contaminated with chromated copper arsenate; Implications for the remediation of arsenic-contaminated soils and for the study of arsenic in plants.

The objective of this study was to establish baseline concentrationsfor 15 potentially toxic elements (Ag, As, Ba, Be, Cd, Cr, Cu, Hg, Mn, Mo, Ni, Ph, Sb, Se, and Zn) based on 448 representative Florida surface soils using microwave assisted HNO3-HCI-HF digestion. Baseline concentrations of those elements were (mg kg-1): Ag 0.072.50, As 0.02-7.01, Ba 1.67-112, Be 0.04-4.15, Cd 0-0.33, Cr0.89-80.7, Cu 0.22-21.9, Hg 0.00075-0.0396, Mo 0.13-6.76, Ni 1.70-48.5, Ph 0.6942.0, Sb 0.06-0.79, Se 0.01-1.11, and Zn 0.89-29.6, respectively. Upper baseline values for most elements corresponded with these reported in literature, except Ba, Hg, Mn, Sb, and Zn, which were 3 to 23 times lower. Soil properties, including pH, organic carbon (OC), particle size, cation-exchange capacity (CEC), available water, extractable base, extractable acidity, total Ca, Mg, P, K, Fe, and A1 concentrations, were related to metal concentrations using factorial analysis. Eight factors were identified (total Fe and AI, CEC, pH, clay, OC, total Ni and Mo, total Sb and Pb, and total Hg) and accountedfor 87% of the total variance, suggesting that metal concentrations were primarily controlled by soil compositions. Multiple regression of elemental concentrations against total Fe, total AI, clay, OC, CEC,and pH was significant for all elements. Partial correlation coefficients indicated that total Fe and/or AI explained most of the variance for Mn, Ni, Ba, Be, Hg, As, Cd, Cr, Cu, Mo, Pb, and Zn concentrations. Most of the variance in Se was related to clay, whereas those of Ag and Sb related to clay and total AI. [ABSTRACT FROM AUTHOR]

Abstract: This field study evaluated the effectiveness of three best management practices (BMPs) in reducing the weathering of Pb-bullets in a shooting range. The BMPs included replacing soil berm with sand berm, liming sand berm, and removing Pb-bullets from soil berm. Berm samples were collected before and after implementing BMPs and analyzed for total Pb and/or water-soluble Pb. After 11 months of operation, the total Pb concentrations in the sand berm (57mgkg−1) were significantly lower than that in the soil berm (277mgkg−1). The reduced weathering of Pb-bullets in the sand berm was attributed to its lower moisture content and organic matter as both water and CO2 are critical in chemical weathering. Though liming reduced total Pb concentrations in the sand berm from 497–777 to 302–362mgkg−1 after 15 months of application, it increased water-soluble Pb in some cases. While removal of Pb-bullets removed the sources of Pb, X-ray diffraction analysis indicated that its abrasive action transferred metallic Pb to the soil fraction (<2mm), with total Pb in soil berm increasing from 4,694 to 11,479mgkg−1. While all BMPs can be applied to mange Pb in shooting ranges, cautions need to be excised to minimize the adverse impacts. [Copyright &y& Elsevier]

Abstract: Shooting range soils with elevated Pb contents are of environmental concern due to their adverse impacts on human and animals. In Florida, the problem merits special attention because of Florida''s sandy soil, high rainfall, and shallow groundwater level, which tend to favor Pb migration. This study used large intact soil column to examine colloid-facilitated Pb transport in two Florida shooting-range soils with different physicochemical properties (e.g., organic carbon content, pH, and clay content). Simulated rainwater (SRW) was pumped through the intact soil columns under different ionic strengths (0.07 and 5mmolL−1) and flow rates (2.67, 5.30 and 10.6cmh−1) to mobilize Pb and soil colloids. Our results showed that colloids dominated Pb transport in both soils and there was a significant correlation between colloids and Pb in the leachates. Decreases in ionic strength and increases in flow rate enhanced the release of both colloids and Pb in the soils. Size fraction analyses showed that in OCR soils (sandy soils with low organic carbon), most of the Pb (87%) was associated with coarse colloid fraction (0.45–8μm). However, high Pb level (66%) was found in the dissolved and nano-sized colloid fraction (<0.1μm) in the MPR soils (sandy soils with high organic carbon). This suggests that soil properties are important to Pb migration in soils and groundwater. Our study indicated that colloids play an important role in facilitating Pb transport in shooting range soils. [Copyright &y& Elsevier]

Arsenic exposure from wood treated with chromated copper arsenate (CCA) remains a concern due to its presence around homes. This study evaluated children's exposure to As from CCA-treated staircases through determination of bioaccessible soil As and measurements of dislodgeable As on hand railings, steps and surfaces of household objects impacted by CCA–wood leachate. Total As concentrations in 84 soil samples from 4 apartment complexes were elevated at 1.2–66.6mg/kg with bioaccessible As at 17–84%. Deterministic risk equations were used to estimate daily doses of As in children with estimates ranging from 0.41–54.9μg/day from ingestion of dislodgeable As. Lifetime average daily doses from ingestion of dislodgeable As and soil ranged from 8.1×10−6 to 3.0×10−5 mg/kg/day, with estimated cancer risks being 1.2–4.5×10−5. Collectively, these results highlight potential health risks in children who have near-daily exposure to As from CCA-wood and are consistent with estimates generated by USEPA's SHEDS-Wood probabilistic exposure model. [ABSTRACT FROM AUTHOR]

Abstract: Contamination of heavy metals represents one of the most pressing threats to water and soil resources as well as human health. Phytoremediation can be potentially used to remediate metal-contaminated sites. This study evaluated the potential of 36plants (17species) growing on a contaminated site in North Florida. Plants and the associated soil samples were collected and analyzed for total metal concentrations. While total soil Pb, Cu, and Zn concentrations varied from 90 to 4100, 20 to 990, and 195 to 2200mg kg−1, those in the plants ranged from 2.0 to 1183, 6.0 to 460, and 17 to 598mg kg−1, respectively. None of the plants were suitable for phytoextraction because no hyperaccumulator was identified. However, plants with a high bioconcentration factor (BCF, metal concentration ratio of plant roots to soil) and low translocation factor (TF, metal concentration ratio of plant shoots to roots) have the potential for phytostabilization. Among the plants, Phyla nodiflora was the most efficient in accumulating Cu and Zn in its shoots (TF=12 and 6.3) while Gentiana pennelliana was most suitable for phytostabilization of sites contaminated with Pb, Cu and Zn (BCF=11, 22 and 2.6). Plant uptake of the three metals was highly correlated, whereas translocation of Pb was negatively correlated with Cu and Zn though translocation of Cu and Zn were correlated. Our study showed that native plant species growing on contaminated sites may have the potential for phytoremediation. [Copyright &y& Elsevier]

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic contaminants, which are found in soils throughout the U.S. The objective of this study was to determine the background concentrations, distributions, and sources of 16 USEPA priority PAHs in two urban soils. A total of 114 soil samples were collected from two large cities in Florida: Orlando and Tampa. The results showed that soils were dominated by high molecular weight PAHs in both cities. The average ∑16-PAHs in Orlando and Tampa soils were 3227 and 4562 μg kg -1 , respectively. The averages of 7 carcinogenic PAHs based on the benzo[a]pyrene-equivalent (BaP-EQ) concentrations in the two cities were 452 and 802 μg kg -1 . BaP-EQ concentrations in 60-62% of samples were higher than the Florida Soil Cleanup Target Level (FSCTL) for residential soils at 100 μg kg -1 and 20-25% of samples were higher than FSCTL for industrial soils at 700 μg kg -1 . Based on molecular diagnostic ratios and PMF modeling, major sources of soil PAHs in both cities were similar, mainly from pyrogenic sources including vehicle emissions, and biomass and coal combustion. Based on ArcGIS mapping, PAH concentrations in soils near business districts and high traffic roads were higher. Thus, it is important to consider background PAH concentrations in urban soils when considering soil remediation., (Published by Elsevier Ltd.)

Metal concentrations (As, Cd, Pb, Cr, Ba, Co, Ni, Cu, and Zn) in conventional and organic produce were assessed, specifically, five most-consumed vegetables from the US including potato, lettuce, tomato, carrot and onion. They were from four representative supermarkets in a college town in Florida. All vegetables contained detectable metals, while As, Cd, Pb, Cr, and Ba are toxic metals, Co, Ni, Cu, and Zn are nutrients for humans. The mean concentrations of As, Cd, Pb, Cr and Ba in five vegetables were 7.86, 9.17, 12.1, 44.8 and 410 μg/kg for organic produce, slightly lower than conventional produce at 7.29, 15.3, 17.9, 46.3 and 423 μg/kg. The mean concentrations of Co, Ni, Cu, and Zn in five vegetables were 3.86, 58.5, 632, and 2528 μg/kg for organic produce, comparable to conventional produce at 5.94, 68.2, 577, and 2354 μg/kg. For toxic metals, the order followed tomato < lettuce < onion < carrot < potato, with root vegetables being the highest. All metals in vegetables were lower than the allowable concentrations by FAO/WHO. Health risks associated with vegetable consumption based on daily intake and non-carcinogenic risk based on hazard quotient were lower than allowable limits. For the five most-consumed vegetables in the US, metal contents in conventional produce were slightly greater than organic produce, especially for Cd and Pb., (Published by Elsevier Ltd.)

Chinese brake fern (Pteris vittata L.) is a hyperaccumulator of arsenic (As) that grows naturally on soils in the southern United States. It is reasonable to expect that mycorrhizal symbiosis may be involved in As uptake by this fern. This is because arbuscular mycorrhizal (AM) fungi have a well-documented role in increasing plant phosphorus (P) uptake, P and As have similar chemical properties, and ferns are known to be colonized by AM fungi. We conducted a factorial greenhouse experiment with three levels of As (0, 50, and 100 mg kg(-1)) and P (0, 25, and 50 mg kg(-1)) and with and without Chinese brake fern colonized by a community of AM fungi from an As-contaminated site. We found that the AM fungi not only tolerated As amendment, but their presence increased frond dry mass at the highest As application rate. Furthermore, the AM fungi increased As uptake across a range of P levels, while P uptake was generally increased only when there was no As amendment. These data indicate that AM fungi have an important role in arsenic accumulation by Chinese brake fern. Therefore, to effectively phytoremediate As-contaminated soils, the mycorrhizal status of ferns needs to be taken into account.

Contamination of shooting range soils from the use of Pb bullets is under increasing scrutiny. Past research on Pb contamination of shooting ranges has focused on weathering reactions of Pb bullets in soil. The objective of this study was to determine the significance of abrasion of Pb bullets in contributing to soil Pb contamination. This was accomplished by firing a known mass of bullets into sand and analyzing for total Pb after removing bullets, through field sampling of a newly opened shooting range, and a laboratory weathering study. Forty-one mg of Pb were abraded per bullet as it passed through the sand, which accounted for 1.5% of the bullet mass being physically removed. At a shooting range that had been open for 3 months, the highest Pb concentration from the pistol range berm soil was 193 mg/kg at 0.5 m height, and from the rifle range berm soil was 1142 mg/kg at 1.0 m height. Most soils from the field abrasion experiment as well as soil collected from the rifle range had SPLP-Pb >15 microg/l (Synthetic Precipitation Leaching Procedure). Typically, Pb concentration in the rifle range was greater than that of the pistol range. Based on a laboratory weathering study, virtually all metallic Pb was converted to hydrocerussite (Pb3(CO3)2(OH)2), as well as to a lesser extent cerussite (PbCO3) and massicot (PbO) within one week. Our study demonstrated that abrasion of lead bullets and their subsequent weathering can be a significant source of lead contamination in soils of a newly opened shooting range., (Copyright 2004 Elsevier B.V.)