Greenhouse Column Study Research Articles

Human health risk mitigation from arsenic in rice by crop rotation with a hyperaccumulator plant.

Exposure to arsenic (As) from a diet of contaminated rice is a widespread problem and a serious concern in several parts of the world. There is a need to develop sustainable, effective, and reliable strategies to reduce As accumulation in rice. Our goal was to develop and test a simple crop rotation method of alternating rice with the As hyperaccumulator plant, Chinese brake fern (Pteris vitatta L.), to reduce As concentrations in rice grains. A greenhouse column study was performed for 2years using As-contaminated rice paddy soil from West Bengal. Rice was grown under flooded conditions and irrigated with As-contaminated water to simulate field conditions. Chinese brake fern was grown between two rice cycles in experimental columns, while control columns were left unplanted. Our results show that at the end of two cycles, there was a statistically significantdecrease in soil As concentrations in the treatment columns compared to the control columns. After one rotation with the fern, there was a significant decline in As concentrations in rice grains in treatment plants and a concomitant decline in both noncarcinogenic and carcinogenic health risks. Our results indicate that there could be substantial benefit in implementing this simple crop rotation model to help lower human health risks from As exposure via rice ingestion.

A combined chemical and phytoremediation method for reclamation of acid mine drainage-impacted soils.

Production of acid mine drainage (AMD) and acid sulfate soils is one of the most concerning environmental consequences associated with mining activities. Implementation of appropriate post-mining AMD management practices is very important to minimize environmental impacts such as high soil acidity, soil erosion, and metal leachability. The objective of this study was to develop a cost-effective and environment-friendly "green" technology for the treatment of AMD-impacted soils. This study utilized the metal-binding and acid-neutralizing capacity of an industrial by-product, namely drinking water treatment residuals (WTRs), and the extensive root system of a metal hyper-accumulating, fast-growing, non-invasive, high-biomass perennial grass, vetiver (Chrysopogon zizanioides L.) to prevent soil erosion. Aluminum (Al)-based and calcium (Ca)-based WTRs were used to treat AMD-impacted soil collected from the Tab-Simco coal mine in Carbondale, IL. Tab-Simco is an abandoned coal mine, with very acidic soil containing a number of metals and metalloids such as Fe, Ni, Zn, Pb, and As at high concentrations. A 4-month-long greenhouse column study was performed using 5% and 10% w/w WTR application rates. Vetiver grass was grown on the soil-WTR mixed media. Turbidity and total suspended solid (TSS) analysis of leachates showed that soil erosion decreased in the soil-WTR-vetiver treatments. Difference in pH of leachate samples collected from control (3.06) and treatment (6.71) columns at day 120 indicated acidity removal potential of this technology. A scaled-up simulated field study was performed using 5% WTR application rate and vetiver. Soil pH increased from 2.69 to 7.2, and soil erosion indicators such as turbidity (99%) and TSS (95%) in leachates were significantly reduced. Results from the study showed that this "green" reclamation technique has the potential to effectively treat AMD-impacted soils.

Aluminum-Based Water Treatment Residual Use in a Constructed Wetland for Capturing Urban Runoff Phosphorus: Column Study

Aluminum-based water treatment residuals (Al-WTRs) have a strong affinity to sorb P. In a proof- of-concept greenhouse column study, Al-WTR was surface-applied at rates equivalent to 0, 62, 124, and 248 Mg ha −1 to 15 cm of soil on top of 46 cm of sand; Al-WTR rates were estimated to capture 0, 10, 20, and 40 years of P from an urban watershed entering an engineered wetland in Boise, ID, USA. Creeping red fescue (Festuca rubra) was established in all columns; one set of columns received no Al-WTR or plants. After plant establishment, once per week over a 12-week period, ∼1.0 pore volumes of ∼0.20 mg P L −1 were added to each column. Infiltration rates were measured, leachate was collected and analyzed for soluble P, and fescue yield, P concentration, and uptake were deter- mined. After plant harvest, the sand, soil, and the Al- WTR layer were collected and analyzed for Olsen P; amorphous Al, Fe, and P; P storage capacity (PSC); and soluble + Al + Fe-bound, occluded, and Ca-bound P phases. Infiltration rate increased only due to the pres- ence of plants. Leached P decreased (50 %) with plants present; Al-WTR further reduced soluble P leaching losses (60 %). Fescue yield, P concentration, and uptake increased with increasing Al-WTR rate, due to Al-WTR sorbing and potentially making P more plant available; Olsen-extractable P increased with increasing Al-WTR rate, supporting this contention. The PSC was reduced with the 62 Mg ha −1 Al-WTR rate but maintained with greater Al-WTR rates. The 124 and 248 Mg ha −1 Al- WTR rates also contained greater P associated with the soluble + Al + Fe and occluded phases which should be stable over the long term (e.g., decadal). It was recom- mended to apply Al-WTR near the 124 and 248 Mg ha −1 rates in the future to capture urban runoff soluble P in the Boise, ID, engineered wetland.

Effects of soil types and forms of arsenical pesticide on rice growth and development

For decades, repeated and widespread use of arsenical pesticides has significantly contributed to arsenic contamination in soils. Residues from the overuse of these arsenicals may result in phytotoxicity to crops, which will depend on soil types, plant species and the toxicity of arsenical pesticides. A greenhouse column study was conducted to evaluate the effect of two pesticides, i.e. one organic (dimethylarsinic acid) and one inorganic (sodium arsenate), on the vegetative response of rice as a function of soil properties. Four soils with varying arsenic retention capabilities at two different pesticide amendment rates (675 and 1500 mg/kg) representing the worst case scenarios in superfund sites were used. Results showed that arsenic availability to rice was mainly influenced by soil physico- chemical properties. The soil with the lowest arsenic retention capacity had the highest arsenic concentration in the leachate as well as in the plant tissue. In contrast, for soils with higher arsenic retention capacity, higher concentrations of arsenic were found in the surface soil which resulted in the inhibition of plant growth. There was no significant difference between labile arsenic / plant-available arsenic irrespective of the form of arsenical pesticide used. Plant growth parameters such as biomass, shoot height, root length decreased with increased arsenic concentrations in all soils. A significant negative correlation (P<0.05) was observed between the phytoavailable arsenic and plant growth response. Interestingly, the form of arsenical pesticide used did not impact arsenic uptake or shoot growth but significantly impacted root growth.

Matrix‐based Fertilizers Reduce Nutrient and Bacterial Leaching after Manure Application in a Greenhouse Column Study

We tested the efficacy of matrix-based fertilizers (MBFs) to reduce Escherichia coli and Enterococcus spp., NH(4), NO(3), dissolved reactive phosphorus (DRP), and total phosphorus (TP) in leachate and soil after dairy manure application in greenhouse column studies. The MBFs are composed of inorganic N and P in compounds that are relatively loosely bound (MBF8) to more tightly bound (MBF9) mixtures using combinations of starch, cellulose, lignin, Al(2)(SO(4))(3)18H(2)O, and/or Fe(2)(SO(4))(3)3H(2)O to create a matrix that slowly releases the nutrients. One day after the first dairy manure application, E. coli numbers were greater in leachate from control columns than in leachate from columns receiving MBFs. After three dairy manure applications, E. coli and Enterococcus spp. numbers in leachates were not consistently different between controls and columns receiving MBFs. When MBF8 was applied to the soil, the total amount of DRP, TP, NH(4), and NO(3) in leachate was lower than in the control columns. Bermudagrass receiving MBFs had greater shoot, root, and total biomass than grass growing in the control columns. Grass shoot, root, and total biomass did not differ among columns receiving MBFs. Nitrogen and phosphorus bound to the Al(2)(SO(4))(3)18H(2)O or Fe(2)(SO(4))(3)3H(2)O-lignin-cellulose matrix become gradually available to plants over the growing season. The MBF8 and MBF9 formulations do not depend on organic or inorganic coatings to reduce N and P leaching and have the potential with further testing and development to provide an effective method to reduce N and P leaching from soils treated with animal waste.

Lead fractionation and bioaccessibility in contaminated soils with variable chemical properties

The hazard imposed by trace elements within soils is dependent on soil properties and the relative distribution of metal species. Hence, a greenhouse column study was conducted to investigate the geochemical speciation and bioaccessibility of lead (Pb) as a function of soil properties. Four different soil types (Immokalee, Belle Glade, Tobosa and Millhopper series) varying in physico-chemical properties were selected and amended with Pb as Pb(NO3) at 400, 800, and 1,200 mg kg−1. A sequential extraction was employed to define the reactive metal pool, which was correlated with Pb bio-accessibility as determined by the physiologically based extraction test. Results show that Pb was mainly distributed in soluble+exchangeable phase in Immokallee (82%) and Millhopper (45%) series, and carbonate and Fe+Mn oxide fractions in Belle Glade (14–74%) and Tobosa (31–64%) series at time zero. With soil aging, Pb underwent chemical transformations in the soils and the majority of added Pb was associated with Fe+Mn oxide fraction (64–81%). Also, Pb bioaccessibility varied widely as a function of soil type and soil aging. Gastric phase (IVG-S) extracted 34–81% and 29–75% and the absorbed intestinal phase (IVG-AI) extracted 12–79% and 12–45% of amended Pb in all the soils at time zero and 6 months, respectively. Among soil types, Tobosa and Belle Glade showed reduced bioaccessibility relative to Immokalee and Millhopper. Statistical analysis revealed that the IVG-S Pb decreases as soil organic matter and cation exchange capacity (CEC) increases and total P decreases. While the Mehlich extractable P and Ca+Mg, total Fe+Al and organic matter predicted the Pb in an intestinal system.

Matrix-Based Fertilizers Reduce Nutrient Leaching While Maintaining Kentucky Bluegrass Growth

We tested the efficacy of matrix-based fertilizers (MBFs) to improve Kentucky bluegrass (Poa pratensis L.) growth while reducing NH, NO3, dissolved reactive phosphorus (DRP), and total phosphorus (TP) compared to commercial slow-release fertilizer (SRF) Polyon®, ESN®, and Avail® in greenhouse column studies. The MBFs covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF6) and more tightly bound compounds (MBF7) with Al(SO4)318H2O and/or Fe2(SO4)33H2O and with high ionic exchange compounds starch, cellulose, and lignin. The total amount of NO3 and NH4 leached was greater from columns receiving Polyon® and ESN® fertilizers than all other treatments. The MBF6+Avail® or MBF7+Avail® fertilizers leached 64–68% less NO3 than Polyon® (43-0-0) and ESN® (46-0-0), and 73–76% less TDP and TP than Avail® (10-34-0). A greater amount of NO3 was leached from the MBF6+Avail® and the MBF7+Avail® treatments than the other MBF fertilizer treatments. Shoot and root biomass were greater when plants received the Avail®, MBF6+Avail®, and MBF7+Avail® fertilizer treatments than the other fertilizer treatments. When combined with small quantities of commercial SRFs, these new MBFs were able to maintain plant growth while reducing N and P leaching. These new MBF formulations do not depend on organic or inorganic coatings to reduce N and P leaching and with further testing and development could be effective commercial fertilizers.

The Influence of Form and Rate on the Efficacy of Matrix-Based Fertilizers to Reduce Nutrient Leaching

We tested the efficacy of matrix-based fertilizers (MBFs) to reduce , , and total phosphorus (TP) leaching compared to Osmocote 14-14-14, a commercial slow release fertilizer (SRF) in greenhouse column studies. The MBFs covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF4) and more tightly bound compounds (MBF5) with and/or and with high ionic exchange compounds starch, chitosan, and lignin. When N and P are released, the chemicals containing these nutrients in the MBF bind N and P to an and/or starch- chitosan- lignin matrix. SRF leachate contained a greater amount of , , DRP, and TP than leachate from MBF4 and MBF5 regardless of whether fertilizers were pellets, banded or broadcast, or fertilizer rate. St Augustine grass growing in soils receiving MBF4 and MBF5 had decreased shoot biomass by 49% to 56% and decreased total biomass by 33% to 46% respectively as grass receiving SRF. Although further greenhouse and field testing are necessary, results of this initial investigation are promising and with further development, testing, and rate calibration should be competitive with commercial fertilizers in environmentally sensitive markets.

Revegetation of High Zinc and Lead Tailings with Municipal Biosolids and Lime: Greenhouse Study

Acidic (pH 4.1) and high Cd, Pb, and Zn mine tailings (mean +/- SD: 17 +/- 0.4, 3800 +/- 100, and 3500 +/- 100 mg kg(-1), respectively) from an alluvial tailings deposit in Leadville, Colorado were amended with municipal biosolids (BS) (224 Mg ha(-1)) and different types of lime (calcium carbonate equivalent of 224 Mg ha(-1) CaCO3) in a greenhouse column study to test the ability of the amendments to neutralize surface and subsoil acidity and restore plant growth. The types of lime included coarse, agricultural, and fine-textured lime (CL, AL, and FL), sugar beet lime (SBL), and lime kiln dust (LK). The FL was also added alone. All treatments increased bulk pH in the amended horizon in comparison to the control, with the most significant increases observed in the FL, SBL+BS, and LK+BS treatments (7.33, 7.34, and 7.63, respectively). All treatments, excluding the FL, increased the pH in the horizon directly below the amended layer, with the most significant increases observed in the SBL+BS and LK+BS treatments (6.01 and 5.41, respectively). Significant decreases in 0.01 M Ca(NO3)2-extractable Zn and Cd were observed in the subsoil for all treatments that included BS, with the largest decrease in the SBL+BS treatment (344 and 3.9 versus 4 and 0.1 mg kg(-1) Zn and Cd, respectively). Plant growth of annual rye (Lolium multiflorum L.) was vigorous in all treatments that included BS with plant Zn, Cd, and Pb concentrations reduced over the control.

Matrix based fertilizers reduce nitrogen and phosphorus leaching in three soils

We compared the efficacy of matrix based fertilizers (MBFs) formulated to reduce NO 3 - , NH 4 + , and total phosphorus (TP) leaching, with Osmocoate ® 14-14-14, a conventional commercial slow release fertilizer (SRF) and an unamended control in three different soil textures in a greenhouse column study. The MBFs covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF 1) to more moderately bound (MBF 2) and more tightly bound compounds (MBF 3) mixed with Al(SO 4) 3H 2O and/or Fe 2(SO 4) 3 and with high ionic exchange compounds starch, chitosan and lignin. When N and P are released, the chemicals containing these nutrients in the MBF bind N and P to a Al(SO 4) 3H 2O and/or Fe 2(SO 4) 3 starch–chitosan–lignin matrix. One milligram (8000 spores) of Glomus intradices was added to all formulations to enhance nutrient uptake. In all three soil textures the SRF leachate contained a higher amount of NH 4 + , NO 3 - and TP than leachate from all other fertilizers. In all three soils there were no consistent differences in the amount of NH 4 + , NO 3 - and TP in the MBF leachates compared to the control leachate. Plants growing in soils receiving SRF had greater shoot, root and total biomass than all MBFs regardless of Al(SO 4) 3H 2O or Fe 2(SO 4) 3 additions. Arbuscular mycorrhizal infection in plant roots did not consistently differ among plants growing in soil receiving SRF, MBFs and control treatments. Although the MBFs resulted in less plant growth in this experiment they may be applied to soils growing plants in areas that are at high risk for nutrient leaching to surface waters.

Matrix Based Fertilizers Reduce Nitrogen and Phosphorus Leaching in Greenhouse Column Studies

We tested the efficacy of matrix based fertilizer formulations (MBF) that reduce NH4, total phosphorus (TP), total reactive phosphorus (TRP) and dissolved reactive phosphorus (DRP) in leachate. The MBF formulations cover a range of inorganic N and P in compounds that are relatively loosely bound (MBF1) to more moderately bound (MBF2) and more tightly bound compounds (MBF3) mixed with Al(SO4)3 H2O and/or Fe2(SO4)3 and with the high ionic exchange compounds starch, chitosan and lignin. Glomus interadicies, a species of arbuscular mycorrhizal fungal spores that will form mycorrhizae in high nutrient environments, was added to the MBF formulations to increase plant nutrient uptake. When N and P are released from the inorganic chemicals containing N and P the matrix based fertilizers likely bind these nutrients to the Al(SO4)3 H2O and/or Fe2(SO4)3 starch–chitosan–lignin matrix. We tested the efficacy of the MBFs to reduce N and P leaching compared to Osmocote® 14-14-14, a slow release fertilizer (SRF) in sand filled columns in a greenhouse study. SRF with and without Al and Fe leached 78–84% more NH4, 58–78% more TP, 20–30% more TRP and 61–77% more than MBF formulations 1, 2, and 3 in a total of 2.0 liters of leachate after 71 days. The concentration and amount of NO3 leached among SRF and MBF formulations 1 and 2 did not differ. The SRF treatment leached 34% less NO3, than MBF3. Total plant weight did not differ among fertilizer treatments. Arbuscular mycorrhizal infection did not differ among plants receiving SRF and MBF formulations 1, 2 and 3. Although further greenhouse and field testing are called for, results of this initial investigation warrant further investigation of MBFs.

Eastern Gamagrass Root Penetration in Adverse Subsoil Conditions

Eastern gamagrass [Tripsacum dactyloides (L.) L] (EG) is reported to exhibit acid tolerance and root penetration through claypans. To study its root growth in these conditions, a greenhouse column study was conducted under simulated soil stress conditions, using EG and sordan [Sorghum × drummondii (Steud.) Millsp. &amp; Chase] as a comparison species. Treatments consisted of incomplete factorial combinations of plant species (EG and sordan), soil water potential (−10 and –300 kPa), lime (pH 3.5 and 4.8), and soil bulk density (Db) (1.3 and 1.7 g cm−3). The treatments were arranged as a randomized complete block design (RCBD). For some of the response variables that were analyzed at different depths, depth was considered as a subplot factor. Treatments were applied to Al‐toxic Tatum Bt horizon material (clayey, fine, mixed, semiactive, thermic Typic Hapludults) used in the middle 30‐cm section of 15 by 60‐cm polyvinyl Cl (PVC) columns. Soil strength was determined at harvest by cone penetrometer resistance. Results indicated that EG tolerated acid, Al‐toxic conditions, while sordan roots were sensitive to the low pH conditions. Eastern gamagrass roots penetrated high soil strength layers that inhibited sordan root growth. The characteristics of acid, Al tolerance, and penetration of high soil strength make EG valuable in establishing grassed buffers, vegetative conservation barriers, and pastures in extremely acid or dense soils.

Phosphorus Leaching from Biosolids‐Amended Sandy Soils

Increasing emphasis on phosphorus (P)-based nutrient management underscores the need to understand P behavior in soils amended with biosolids and manures. Laboratory and greenhouse column studies characterized P forms and leachability of eight biosolids products, chicken manure (CM), and commercial fertilizer (triple superphosphate, TSP). Bahiagrass (Paspalum notatum Flugge) was grown for 4 mo on two acid, P-deficient Florida sands, representing both moderate (Candler series: hyperthermic, uncoated Typic Quartzipsamments) and very low (Immokalee series: sandy, siliceous, hyperthermic Arenic Alaquods) P-sorbing capacities. Amendments were applied at 56 and 224 kg P(T) ha(-1), simulating P-based and N-based nutrient loadings, respectively. Column leachate P was dominantly inorganic and lower for biosolids P sources than TSP. For Candler soil, only TSP at the high P rate exhibited P leaching statistically greater (alpha = 0.05) than control (soil-only) columns. For the high P rate and low P-sorbing Immokalee soil, TSP and CM leached 21 and 3.0% of applied P, respectively. Leachate P for six biosolids was <1.0% of applied P and not statistically different from controls. Largo biosolids, generated from a biological P removal process, exhibited significantly greater leachate P in both cake and pelletized forms (11 and 2.5% of applied P, respectively) than other biosolids. Biosolids P leaching was correlated to the phosphorus saturation index (PSI = [Pox]/[Al(ox) + Fe(ox)]) based on oxalate extraction of the pre-applied biosolids. For hiosolids with PSI < or = approximately 1.1, no appreciable leaching occurred. Only Largo cake (PSI = 1.4) and pellets (PSI = 1.3) exhibited P leaching losses statistically greater than controls. The biosolids PSI appears useful for identifying biosolids with potential to enrich drainage P when applied to low P-sorbing soils.

Eastern Gamagrass Root Penetration in Adverse Subsoil Conditions

Eastern gamagrass [Tripsacum dactyloides (L.) L] (EG) is reported to exhibit acid tolerance and root penetration through claypans. To study its root growth in these conditions, a greenhouse column study was conducted under simulated soil stress conditions, using EG and sordan [Sorghum × drummondii (Steud.) Millsp. & Chase] as a comparison species. Treatments consisted of incomplete factorial combinations of plant species (EG and sordan), soil water potential (−10 and –300 kPa), lime (pH 3.5 and 4.8), and soil bulk density (Db) (1.3 and 1.7 g cm−3). The treatments were arranged as a randomized complete block design (RCBD). For some of the response variables that were analyzed at different depths, depth was considered as a subplot factor. Treatments were applied to Al-toxic Tatum Bt horizon material (clayey, fine, mixed, semiactive, thermic Typic Hapludults) used in the middle 30-cm section of 15 by 60-cm polyvinyl Cl (PVC) columns. Soil strength was determined at harvest by cone penetrometer resistance. Results indicated that EG tolerated acid, Al-toxic conditions, while sordan roots were sensitive to the low pH conditions. Eastern gamagrass roots penetrated high soil strength layers that inhibited sordan root growth. The characteristics of acid, Al tolerance, and penetration of high soil strength make EG valuable in establishing grassed buffers, vegetative conservation barriers, and pastures in extremely acid or dense soils.

Minespoil Amendment with Dry Flue Gas Desulfurization By‐Products: Plant Growth

AbstractOne potential use for alkaline, dry flue gas desulfurization (FGD) by‐products is in reclamation of acidic minespoils. Greenhouse column studies of 8‐mo duration investigated growth and tissue composition of plants grown on three acidic minespoils amended with two dry FGD by‐products (lime injection multistage burners, LIMB; and, pressurized fluidized bed combustion, PFBC). Amendment amounts ranged from 0 to 320 g kg−1 by dry weight. Two minespoils also were amended with sewage sludge at 60 g kg−1 by dry weight. Column mixes were planted with Kentucky 31 tall fescue (Festuca arundinacea Schreb.). After 92 d of growth, fescue was harvested every 30 d for a total of six harvests. Tissue composition was determined on material from the sixth harvest. Root growth was measured at the end of the experiment. Fescue growth was improved by FGD amendments of 30 to 120 g kg−1, but larger amendments caused high pH and cementation, which decreased fescue growth and limited rooting volume. Plant tissue composition was generally within sufficiency ranges for the elements analyzed. Tissue Ca, Mg, and S were increased by FGD amendment, while tissue concentrations of most trace elements were decreased. There was no increase in tissue B from PFBC, however, LIMB application caused B concentrations &gt;100 mg kg−1, which could be toxic to less tolerant species. These results indicate that when applied in amounts equivalent to spoil neutralization needs, dry FGD by‐products can benefit acidic spoil revegetation with little potential for introduction of toxic elements into the food chain.