Showing papers in "Journal of Environmental Quality in 1981"

Changes in soil physical properties due to organic waste applications : a review

Abstract: Land application of organic wastes such as animal manure, municipal wastes, and sewage sludge could alter the soil physical properties. Repeated substantial applications of waste increase the soil organic matter percentage. The available data on effects of waste applications on soil physical properties such as bulk density, water holding capacity at both field capacity and wilting point, and saturated hydraulic conductivity were summarized. Based on data from 12 different sources, 21 soil types, 7 waste types, and 8 crop types, a linear regression analysis of observed increases in soil organic C as a result of waste applications on percent reduction in bulk density indicated a highly significant relationship (r* = 0.69**). The results of an exponential multiple regression analysis of percentage sand and increase in organic C percentage on the percent increase in water holding capacity indicated that approximately 80% of the observed variations in percent increases in water holding capacity, at both field capacity and wilting point, could be attributed to variations in soil texture and soil organic C increases. The data on hydraulic conductivity as well as on infiltration rates are very limited and are not sufficient for quantitative analyses. The limitations of the available data were discussed in terms of identifying future research needs. Additional Index Words: bulk density, organic matter, water holding capacity, hydraulic conductivity. ' Paper no. 6041 of the Journal Series of the North Carolina Agric. Res. Serv., Raleigh, N.C. The use of trade names in this publication does not imply endorsement by the North Carolina Agric. Res. Serv. of the products named, nor criticism of similar ones not mentioned. This research was supported in part by the USEPA on a Grant no. R805011-0-1-0. Received 14 March 1980. ' Assistant Professor of Hydrology, New Mexico Inst. of Mining and Technol., Socorro, N. Mex.; Assistant Professor, AREC, Univ. of Florida, Sanford; Associate Professor, Dep. of Biol. and Agric. Eng., North Carolina State Univ., Raleigh; respectively. Khaleel, R., K. R. Reddy, and M. R. Overcash. 1981. Changes in soil physical properties due to organic waste applications: a review. J. Environ. Qual. 10:133-141. The soil has substantial capacity to treat and assimilate organic wastes. Applying wastes to land at agronomic rates for plant nutrient supply has been the traditional means of waste management. In recent years, there has been an increasing interest in disposal of wastes at rates far in excess of traditional agronomic rates. Application of wastes, either for plant nutrient supply or for disposal purposes, increases the C content of the soil. An increase in C content of the soil increases aggregation, decreases bulk density, increases water holding capacity, and hydraulic conductivity (e.g., Biswas and Khosla, 1971; Gupta et al., 1977; Kladivko and Nelson, 1979; Klute and Jacob, 1949; Mays et al., 1973; Salter and Haworth, 1961; Tiarks et al., 1974; Unger and Stewart, 1974; Volk and Ullery, 1973; Webber, 1978; Weil and Kroontje, 1979; Williams and Cooke, 1961). Furthermore, organic matter and soil aggregation are inversely related to runoff volumes and sediment loss (Wischmeier and Mannering, 1965; 1969). Several investigators, in monitoring runoff water quality from small plot-sized land application areas, reported less runoff volumes from these plots compared to control plots which received no wastes (Hensler et al., 1970; Long, 1979; McCaskey et al., 1971; Young, 1974; Young and Mutchler, 1976). The low runoff losses may be due to improved soil physical properties as a result of waste applications. Because of increased aggregation, less eroJ. Environ. Qual., Vol. 10, no. 2,1981 133 Table l--Pertinent information on various experiments. Location Percent C Years content of Waste type of waste study Soil type Crops grown Waste application Depth of rates incorpoMethod of metric tons ration, incorp@ ha" yr" cm ration Properties studied Remarks Reference Elk River, Minnesota Lafayette, Indiana Anaerobic 14.0 2 Hubbard coarse sludge sand {Udorthentic Haploborollsl 90.1% sand Anaerobic 19.4 1 Celina silt loam sludge {Aquic Haphdalfs}, 22.5% sand Mead, Cattle 32,0 2 Nebraska feadiot

Behavior and Transport of Microbial Pathogens and Indicator Organisms in Soils Treated with Organic Wastes

Abstract: In a critical review of pathogen and indicator-organism transformations and transport from land areas receiving organic wastes, microbial die-off was described assuming first-order kinetics. First-order die-off rate constants (k) were calculated from the literature data for various pathogens and indicator organisms. For indicator organisms average die-off rates were 1.14 day⁻¹ (0.08–9.1) for fecal coliforms, and 0.41 day⁻¹ (0.05–3.87 day⁻¹) for fecal streptococci. For pathogens, the average die-off rates were 1.33 day⁻¹ (0.21–6.93) for Salmonella, 0.68 day⁻¹ (0.62–0.74 day–¹) for Shigella sp., and 1.45 day⁻¹ (0.04–3.69 day⁻¹) for viruses, respectively. Die-off rates increased approximately two times with a 10°C rise in temperature (5–30°C). Microbial die-off increased with decrease in soil moisture and was minimum in a pH range of 6–7. Correction factors were presented to adjust the k values for the changes in temperature, moisture, and pH. Retention of pathogens and indicator organisms by soil particles was described assuming a linear isotherm. Retention of microorganisms increased with an increase in clay content of the soil. Major transport processes reviewed were leaching and surface runoff for land areas receiving animal wastes, and pastures and rangeland watersheds where animals distribute waste directly on the land. Some of the important research needs identified include (i) mechanisms involved in the retention of bacteria and viruses by the soil; (ii) measurement of retention coefficients for some important pathogens and indicator organisms, as a function of physico-chemical properties of soil; (iii) processes involved in the transport of bacteria and viruses along with the percolating water or in runoff water; and (iv) extensive testing of available models.

Environmental Chemistry of the Elements

Abstract: All chapters of the previous edition [see HbA 37, 2103] have been completely rewritten to cover the rapid increase in research in this area. The number of literature citations have been reduced by referring to recent review articles and the book aims at a comprehensive and critical rather than encyclopaedic summary of the data of environmental chemistry. The 1st 4 chapters deal with air, water, rocks and soils; the cycling of C, N, H, O2 and S in the biosphere are covered in 1 chapter and the elemental Other CABI sites 

A Survey of Sorption Relationships for Reactive Solutes in Soil

Abstract: The present study provides a survey of relationships in current use to quantify sorption of reactive solutes by soil. Its purpose is to examine present concepts and to indicate active research directions. Both equilibrium and first-order kinetic sorption models are reviewed. Equilibrium models discussed include the linear, Freundlich, Langmuir, two-surface Langmuir, and competitive Langmuir isotherms. Kinetic sorption models reviewed are the reversible linear, reversible nonlinear, kinetic product, bilinear, mass transfer, Elovich, Fava and Eyring, and two-site kinetic model. The models reviewed appear to provide a reasonably good basis for extrapolation and interpolation of data. There is a continuing need, however, to upgrade these methodologies as demand for accuracy and realism increases. It is expected that the state-of-the-art review provided by this survey will assist in this process.

Transport and Fate of Selected Organic Pollutants in a Sandy Soil

Abstract: Ground waters are increasingly vulnerable to pollution by organic chemicals that migrate through the soil mantle. To assess the minimal protection that soil can be expected to provide ground water, the transport and fates of 13 organic pollutants were studied in a sandy soil with low organic matter content (0.087% organic C). Glass columns were packed with soil to a depth of 140 cm in a manner that preserved to the maximum extent possible the characteristics of the original soil profile. In separate experiments, the columns received 14 cm/day of water containing a mixture of approximately 1.0 or 0.2 mg/liter of each of the organic compounds. Quantities of compunds that volatilize from the soil surface were measured, as well as concentrations in the column effluent. Chloroform (trichloromethane), 1,2-dibromo-3-chloropropane, dichlorobromomethane, 1,2-dichloroethane, tetrachloroethene, 1,1,2-trichloroethane, and trichloroethene were not degraded in this soil. These compounds percolated rapidly through the soil; their retardation factors (velocity of tritiated water through soil divided by apparent velocity of pollutant through soil) were 2.5 or less. Between 19 and 65% of the material applied to the surface percolated to a depth of 140 cm, and the remainder volatilized. Chlorobenze e 1,4-dichlorobenzene, and 1,2,4-trichlorobenzene also percolated through the soil;more » retardation factors were 1.7, 3.4, and 9.4, respectively. Between 26 and 49% of the material applied reached 140 cm. Toluene and nitrobenzene degraded in some of the columns but not in others. In the absence of degradation, 60 and 80% of nitrobenzene and 13% of toluene applied to the soil surface reached 140 cm. The retardation factors were 2.3 or less. Bis(2-chloroethyl)ether did not degrade; 86% of the material applied reached 140 cm, and the compounds's retardation factor was <1.5.« less

Nitrous oxide emissions from cropped fields

Abstract: From mid-May to mid-September 1978, nitrous oxide (N/sub 2/O) emissions from an irrigated corn (Zea mays L.) field in northern Colorado totaled only 2.5 kg N ha/sup -1/, and even smaller losses were measured from a nearby sugarbeet (Beta vulgaris L.) field. Fluxes measured by a simple soil cover method compared favorably with micrometeorological estimates of vertical N/sub 2/O flux density. About 30% of the N/sub 2/O lost from the corn field was emitted during the 2 weeks following fertilization while NH/sub 3/ was being rapidly nitrified, and 59% was evolved during the week following the field's first irrigation, when restricted oxygen diffusion favored denitrification. Other occurrences of irrigation or precipitation exceeding 0.7 cm were also followed by rapid, though much smaller, increases in N/sub 2/O emissions. The flux of N/sub 2/O was not significantly correlated with soil nitrate concentration but was strongly correlated with soil water content and N/sub 2/O concentration in the soil atmosphere, which always exceeded the ambient atmospheric concentration. We found no evidence that either site ever behaved as a sink for tropspheric N/sub 2/O. Total N/sub 2/O emissions from the corn field amounted to only 1.3% of the 200 kg NH/sub 3/-N ha/sup -1/ appliedmore » to the crop, a much smaller fraction than has been used in models predicting the effect of agricultural fertilizers upon stratospheric ozone depletion.« less

The Release of Soil Phosphorus to Runoff in Relation to the Kinetics of Desorption

Abstract: The release of P from surface soil to runoff water under simulated rainfall conditions was investigated for five soils at several rates of fertilizer P application. A simplified kinetic model proposed earlier, describing the desorption of soil P, adequately described both the concentration of soluble P in runoff during an event and mean values for successive events. During an event the logarithm of soluble P concentration decreased linearly as the logarithm of time increased. Mean soluble P concentrations of individual runoff events increased linearly with amount of desorbable P in the surface soil (top 0.5 cm), while the effect of increased rain intensity on concentrations could be explained by a power function related to water/soil ratio. The average depth of runoff-surface soil interaction calculated from the data using the kinetic model ranged from 1.5 to 3.0 mm for the five soils, and was significantly related to degree of soil aggregation. These depths agreed closely with those determined using ³²P as a tracer in earlier studies. The depth of interaction increased with increase in soil slope, kinetic energy of the raindrops, and, to a lesser extent, rainfall intensity. The use of the kinetic model would improve modeling of soluble P loading in runoff.

The Sorption of Soluble Phosphorus by Soil Material during Transport in Runoff from Cropped and Grassed Watersheds 1

Abstract: The adsorption of soluble P by surface soil and suspended sediment material during transport in surface runoff under field and simulated laborato ry conditions was investigated. The soluble P concentration of surface runoff from several Southern Plains cropped and grassed watersheds decreased with an increase in sediment concentration. A linear inverse relationship between soluble P and sediment concentration was significant over a wide range in sediment concentration. The slope values of the relationship were similar for different watersheds on the same major soil type. Using soil from these watersheds in simulated surface runoff, sorption of soluble P added in rainfall was found to occur during transport. The magnitude of this sorption was more closely related to the sorptive capacity of the sediment in the surface runoff than to that of the surface soil material. The results suggest that for unfertilized watersheds and for watersheds where fertilizer P is incorporated into the surface soil, away from the zone of immediate removal in surface runoff, the leaching of P from the vegetative cover can contribute significant amounts of soluble P to runoff, and that soil material may act as a P sink rather than a P source. Additional Index Words: surface runoff, sediment. Sharpley, A. N., R. G. Menzel, S. J. Smith, E. D. Rhoades, and A. E. Olness, 1981. The sorption of soluble phosphorus by soil material during transport in runoff from cropped and grassed watersheds. J. Environ. Qual. 10:211-215. The importance of phosphorus (P) in increasing the rate of biomass production in surface waters from agricultural watersheds is well recognized (Keup, 1968; Ryden et al., 1973; Viets, 1975). Because of the appreciably greater availability of soluble P than sediment-P to aquatic organisms (Syers et al., 1973; Porter, 1975), transformations between soluble and sediment-bound P during transport in runoff are important in determining the short-term potential of runoff for increasing algal growth. Leaching of plant material by rainfall, dissolution of fertilizer material, and desorption of soil P by runoff water can contribute substantial amounts of P to runoff water (Timmons et al., 1970; Schuman et al., 1973; Romkens and Nelson, 1974). However, Burwell et al. (1974) suggested that part of the P released to runoff can be readsorbed by soil material during transport. Furthermore, several studies have attributed observed decreases in the soluble P concentration of stream water, during movement from agricultural watersheds, to sorption by suspended sediment and exposed stream bank material (Wang and Evans, 1970; Taylor and Kunishi, 1971; Sharpley and Syers, 1979). The selective erosion of fine particles, which have a greater capacity 'Contribution from the Dep. of Agron., Oklahoma Agric. Exp. Stn., Oklahoma State Univ., Stillwater, OK 74074, in cooperation with Southern Plains Watershed and Water Qual. Lab., USDA-SEA, Durant, OK 74701. Journal Series no. 3796. Received 23 July 1980. 'Soil Chemists, except E. D. Rhoades, Agricultural Engineer. Address, USDA-SEA, Durant, Okla. Last author's present address is USDA-SEA, Morris, Minn. to sorb P during runoff (Schuman et al., 1976; Menzel, 1980; Sharpley, 1980), enhances sorption of P during transport. Little information is available, however, on the extent and rate to which sorption occurs under field or laboratory conditions. This paper reports on an investigation of the relationship between soluble P and suspended sediment concentrations in runoff from several Southern Plains cropped and grassed watersheds and the sorption of P by soil material from the watersheds. EXPERIMENTAL PROCEDURE Watershed Description Characteristics of the four cropped and seven grassed watersheds used in the study are presented in Table 1. Boundaries of the cropped watersheds were defined by man-made berms, and those of the grassed watersheds by ridges and natural boundaries. The continuously grazed watersheds, R-7 and R-8, were overgrazed, which produced poor vegetative ground cover and allowed active gullying. Similarly, the grassed watershed, W-2, was actively eroding from a large gulley. The amounts of fertilizer P applied to the watersheds are presented in

Ammonia Volatilization from Liquid Swine Manure Applied to Cropland

Abstract: Randomized complete block design field experiments were conducted to determine the effects of rates and methods of liquid swine manure application on volatile NH/sub 3/-N losses from cropland. In addition, a greenhouse study was conducted to determine the effect of wind on the rate of NH/sub 3/-N volatilization from soil and the accuracy of NH/sub 3/-N loss measurements under field conditions. A partially closed system was utilized to directly collect volatilized NH/sub 3/-N from microplots. The NH/sub 3/-N collection system did not accurately estimate volatile N losses when windy conditions existed as often encountered in the field. Using direct measurement of NH/sub 4//sup +/-N in waste before and after exposure to the atmosphere to correct for the low estimates of NH/sub 3/-N loss under field conditions, an average of 48.1% of the volatilized N was collected under greenhouse conditions with relatively constant temperature and wind. The rate of NH/sub 3/-N loss from manure increased with increasing temperature and air movement. The proportions of the applied NH/sub 4//sup +/-N lost as NH/sub 3/-N during a 3.5-day sampling period in the spring from swine manure (pH 6.4) applied to soil (pH 6.4) and corrected for the effect of wind were: 14.0%, 12.2%,more » and 11.2% for the 90, 135, and 180 metric ton/ha, respectively, of surface applied liquid swine manure; 2.5% for both the 90 and 180 metric ton rates, respectively, of injected liquid swine manure; 14.7% for surface applied urea fertilizer (168 kg N/ha); and 65.8% of the applied NH/sub 4//sup +/-N from swine manure surface applied (90 metric tons/ha) on a plastic liner. Fresh swine manure (pH 7.8) surface applied at the rate of 135 metric tons/ha on greenhouse loam soil (pH 7.0) lost 82.5% of the applied NH/sub 4//sup +/-N in an 8-day sampling period.« less

Behavior of Chromium in Soils: IV. Toxicity to Microorganisms

Abstract: The toxicity of Cr to soil bacterial isolates was studied by measuring turbidity of liquid cultures supplemented with Cr(VI) or Cr(III). Ten to 12 ppm Cr(VI) was found inhibitory to most isolates growing in either a soil-extract medium and or in a semisynthetic medium. Gram negative bacteria were more affected than gram positive bacteria by Cr(VI) both at this level and at 1 ppm. Toxicity due to Cr(III) was not observed at similar levels. Nellis loam (Typic Eutrochrept) and Hinesburg fine sandy loam (Entic Haplorthod) samples were treated with 10 and 100 ppm Cr(VI) and 100 ppm Cr(III). All three treatments significantly decreased CO₂ evolution from that of controls for the 3-week duration of the experiment. Extractable Cr(VI) in these soils decreased rapidly during this time, indicating that reduction of the added Cr(VI) was occurring. The toxicity of low levels of Cr(VI) to gram negative bacteria in aqueous culture indicates that soil microbial transformations, such as nitrification, may be affected. The fact that both Cr(III) and Cr(VI) inhibited microbial activity in soil shows that more caution may be needed in handling Cr-containing wastes, regardless of the form of Cr.

The Potential for Ground Water Contamination from Septic Effluents

Abstract: Large populations in both rural and urban areas rely on septic tank soil-absorption treatment systems as the principal disposer of domestic waste materials. Potential ground water pollutants, including pathogens, are removed from percolating drainfield effluents by microbial activity, soil filtration, and adsorption, preventing their entry into ground water. There is accumulating evidence, however, that water supplies in many areas of the United States are receiving increased pollution loads, and the source has frequently been traced to contaminated recharge waters. This paper reviews literature on both the conditions present where conventional disposal systems malfunction, and the mechanisms by which incompletely treated septic wastes may come into contact with various water resources. Current information regarding the function of a drainfield system and an examination of data from recent microbiological investigations on conditions necessary for the removal of enteric organisms from effluent waters is also included. Research needs are addressed with emphasis on problem areas which need further investigation in order to develop safe guidelines for determining the suitability of septic tank systems in relation to regional soil-water conditions.

The Hubbard Brook ecosystem study: Biogeochemistry of lead in the northern hardwood forest.

Abstract: The average annual Pb input to the northern hardwood forest at the Hubbard Brook Experimental Forest in central New Hampshire was 266 g ha/sup -1/ year /sup -1/ based on 4 years of records. Lead output via streamwater and eroded particulate matter was 5.0 and 1.1 g ha/sup -1/ year/sup -1/, respectively. Lead concentration in precipitation averaged 22 ..mu..g liter/sup -1/ and showed a significant decline over the 4 sample years (1975 to 1978). Lead input to the ecosystem via meteorological vectors is accumulated in the forest floor. Total current Pb content of the forest floor was 8.6 kg ha/sup -1/ and showed no significant differences along the elevation gradient of the watershed (400 to 800 m). Lead concentration in the forest floor was maximum on the ridge due to a minimum forest floor mass relative to the rest of the watershed. Within the forest floor, maximum Pb concentration is in the fermented (F) layer. Total Pb content of the forest biomass (stems greater than or equal to 10 cm dbh) was 1248 g ha/sup -1/. Lead concentration in the biota was in the following order: lichens (213 ..mu..g g/sup -1/) > mosses (190 ..mu..g g/sup -1/) tree twigs (26more » ..mu..g g/sup -1/) > roots (20 ..mu..g g/sup -1/) > bark (19 ..mu..g g/sup -1/) > leaves (7 ..mu..g g/sup -1/) = bracket fungi (7 ..mu..g g/sup -1/) > wood (0.7 ..mu..g g/sup -1/). Disturbance of the forest ecosystem through harvest cutting, other than through increased runoff, increased erosion, and transport of particulate matter, does not alter the biogeochemistry of Pb and does not result in increased mobility and export of Pb due to gross or subtle alterations of the behavior of Pb in the ecosystem.« less

The Contribution of Phosphorus Leached from Crop Canopy to Losses in Surface Runoff

Abstract: Simulated rainfall (6 cm/hour) was used to leach P from growing cotton (Gossypium hirsutum), sorghum (Sorghum sudanense), and soybean (Glycine max.) plants as a function of soil type and time interval between rainfall events. The relative contribution of plant material and surface soil to the transport of soluble P in surface runoff was estimated. The amount of soluble P in plant leachate, collected before contacting the soil surface, was found to increase with plant age and soil-water stress when changes in leaf area index were accounted for. A period of at least 1 day between rainfall events was needed for P to reaccumulate on the lead surface. The contribution of soluble P in plant leachate to that transported in suface runoff was estimated as the difference in runoff concentration between planted and bare soil. When plants were subject to a soil P stress, canopy leachate contributed the major proportion (90%) of that transported in surface runoff. With an increase in plant age from 42 to 82 days, the contribution of plant leachate to surface runoff increased from approximately 20 to 60%. The possible sorption of leached P is discussed along with estimating leaching losses in improving the predictive ability ofmore » nutrient models.« less

Use of straw for removal of heavy metals from waste water

Abstract: The efficiency of barley straw (Hordeum vulgare L.) in removing heavy metals from solutions was investigated in capacity and in column experiments. In the capacity experiments the efficiency of the straw was compared to that of activated carbon, pine sawdust, and CaCO/sub 3/. It was found that 1 g of straw was able to adsorb amounts of Zn, Cu, Pb, Ni, and Cd ranging from 4.3 to 15.2 mg. One gram of activated carbon removed from 6.2 to 19.5 mg and pine sawdust from 1.3 to 5.0 mg. From 1.6 to 19.8 mg of the different metals were precipitated by CaCO/sub 3/. The efficiency of the straw was not reduced in column experiments where flow rates of 167 to 370 ml/min were used. The efficiency of the straw was improved by 10 to 90% when being mixed with CaCO/sub 3/. A column packed of barley straw and saturated with Cu was regenerated with 1 liter of acid (less than or equal to 1.0N HCl) and could be reused at least five times.

Effect of Anhydrous Ammonia Fertilization on Emission of Nitrous Oxide from Soils

Abstract: A simple method was developed for accurate injection of anhydrous ammonia in field studies to assess the effects of this fertilizer on emissions of nitrous oxide (NO/sub 2/) from soils. Use of this method and of a chamber technique for measurement of N/sub 2/O emissions showed that fertilization of three Iowa soils with anhydrous ammonia (250 kg n/ha) led to a very marked increase in emission of N/sub 2/O. Emissions of N/sub 2/O-n from the fertilized soils in 139 days ranged from 12.1 to 19.6 kg/ha and averaged 15.6 kg/ha. The corresponding emissions from the unfertilized soils ranged from 1.7 to 2.5 kg/ha and averaged 2.0 kg/ha. Most of the N/sub 2/O evolved from the fertilized soils was produced within 42 days after fertilization, and N/sub 2/O emissions from these soils within 42 days after fertilization, and N/sub 2/O emissions from these soils 96 days after fertilization were not appreciably greater than those from the corresponding unfertilized soils. The fertilizer-induced emissions of N/sub 2/O-n observed after application of anhydrous ammonia greatly exceeded those detected in similar field studies using other N fertilizers and represented 4.0 to 6.8% of the fertilizer N applied.

Vegetative Filter Treatment of Livestock Feedlot Runoff

Abstract: Four vegetative filters were installed on feedlots in central and northern Illinois. Two configurations were used: channelized Dow and overland Dow. After settling for partial solids removal, runoff was applied directly to the fUters and allowed to Dow from the inlet to the outlet section. Results from measurement analyses and sampling of influent, efOuent, and surface Dow at intermediate points were re-

Uptake by wheat of cadmium and other heavy metal contaminants in phosphate fertilizers

Abstract: A field experiment was conducted to determine uptake of Cd and other heavy metals by winter wheat (Triticum aestivum L.) from three diammonium phosphate (DAP) fertilizers containing 2, 74, and 153 ..mu..g Cd/g. A phosphorus-deficient Paden silt loam (Glossic Fragiudult, pH 4.7) was limed at two rates and treated with the DAP sources at a rate of 50 kg of P/ha (100 lb of P/sub 2/O/sub 5//acre). Grain yields were higher at pH 5.9 than at pH 5.1, were significantly increased by P applications, and results were similar using all DAP sources. Concentrations of Cd in both grain and straw were significantly increased only with application of high-Cd DAP to the low-lime soil. Cadmium concentrations in grain increased from 0.028 to 0.086 ..mu..g/g, and those in straw increased from 0.067 to 0.118 ..mu..g/g (dry weight basis) with application of low-Cd DAP and high-Cd DAP, respectively, and were lower on the high-lime soil. Concentrations of Cu, Mn, Ni, and Zn in both grain and straw were not significantly affected by DAP source. Results for a second year on the same plots limed to pH 5.8 and 7.0 and treated again with the same DAP sources were similar to those for themore » first year, except that heavy metal uptake was generally lower. Results suggest that Cd concentrations in wheat products are not significantly changed by the phosphate fertilization and crop production practices in general use in the United States at this time.« less

Occurrence of Naturally High Cadmium Levels in Soils and Its Accumulation by Vegetation

Abstract: A survey of soils in the Santa Monica Mountains of Los Angeles and Ventura Counties, Calif., was conducted to determine the relationship between parent materials and soil Cd contents. Twenty-four series were sampled and analyzed for Cd after digestion in 4N HNO/sub 3/. Residual soils developed from shale parent materials had the greatest Cd concentrations, with a mean of 7.5 ..mu..g/g, whereas soils developed from sandstone and basalt had the lowest Cd concentrations, with a mean of 0.84 ..mu..g/g. Alluvial soils with parent materials from mixed sources had an intermediate mean Cd content of 1.5 ..mu..g/g. A more extensive survey of the dominant soil series of the area was carried out and the Millsholm series, mapped in 30% of the area, was found to have a mean Cd content of 7.3 ..mu..g/g. A greenhouse vegetable study conducted with seven soils from the area, representing a range of Cd concentrations, showed that the Cd present naturally in these soils was absorbed by the vegetables in amounts sufficient to be of public health concern.

Productivity of field-grown soybeans exposed to acid rain and sulfur dioxide alone and in combination

Abstract: Sulfur dioxide (SO/sub 2/)-fumigated and unfumigated field plots of soybeans (Glycine max cv. Wells) were exposed to acid (pH 3.1) or control (pH approx. =5.3) precipitation simulants to determine effects on growth and productivity. The precipitation simulants were applied at approximately 5-day intervals in July and August with a total of 3.4 cm applied in 1977 and 4.5 cm in 1978. Sulfur dioxide fumigations of approx. =4-hour durations were performed 24 times in 1977 and 17 times in 1978, resulting in an average fumigation concentration of 0.79 ppm (89.6 ppmin equilibriumhour dose) SO/sub 2/ the 1st year and 0.19 ppm (13.5 ppmin equilibriumhour) the 2nd. The acid precipitation simulant produced no statistically significant effect on seed yield in either year and a 4% increase in seed size in 1978. The simulated acid rain may have contributed to the nutritional requirements of soybeans by providing S and N during the critical pod-filling stage. Sulfur dioxide exposure decreased seed yields in both 1977 and 1978 by >35 and 12%, respectively. Accelerated senescence, as suggested by increased leaf fall, may be responsible for the decreased yield in the SO/sub 2/-exposed plants. The SO/sub 2/ exposure appeared to negate the positive acid rain effectmore » on seed size observed in 1978, when the two treatments were combined. Acid precipitation apparently increased the reduction in seed weight resulting from SO/sub 2/ exposure in 1977. Although visible injury was induced by acid rain exposure in a chamber study, only a small percentage (<1%) of tissue was affected and there was no apparent effect on plant growth. The results of these studies suggest that the possibility for harmful effects on soybean yield from acid precipitation of a magnitude used in this study are minimal; however, soybean yields may be decreased by SO/sub 2/ exposures« less

Adsorption of Cadmium on Soil Constituents in the Presence of Complexing Ligands

Abstract: The objective of this study was to evaluate the effect of natural and synthetic complexing agents on Cd²⁺ adsorption characteristics of metal hydroxides and silicate clay minerals. The solution pH at which 50% of the initial solution Cd²⁺ was adsorbed was 5.40, 7.00, 7.80, and 8.30 for Al(OH)₃, Fe(OH)₃, montmorillonite, and kaolinite, respectively. The presence of citrate (C₆H₅O₇³⁻) depressed Cd adsorption on Al(OH)₃, by approximately 25% in acidic solutions. The addition of EDTA (C₁₀H₁₆O₈N₂) depressed the Cd adsorption on both Al and Fe hydroxides, montmorillonite, and kaolinite in acidic and alkaline solutions. The water-soluble organic fraction from sewage sludge enhanced Cd adsorption by both kaolinite and montmorillonite in alkaline solutions. The water-soluble organic fraction from an organic soil (Terra Ceia muck) increased Cd adsorption by Fe(OH)₃ only under acidic conditions. Preliminary results indicated that considerations of Cd retention by soil constituents should include not only the aqueous chemistry of Cd and the surface chemistry of the adsorbent, but also the chemistry of natural and synthetic complexing agents. The interaction of Cd and various complexing agents can play an important part in determining the fate of this metal in the soil-water-plant environment.

Effect of simulated acid rain on nitrification and nitrogen mineralization in forest soils

Abstract: To determine the possible microbiological changes in soil resulting from acid rain, columns containing samples of forest soils were leached with either a continuous application of 100 cm of simulated acid rain (pH 3.2-4.1) at 5 cm/hour or an intermittent 1.5-hour application of 1.2 cm of simulated acid rain twice weekly for 19 weeks. The upper 1.0- to 1.5-cm portions of soil from treated columns were used to determine the changes in inorganic N levels in the soil. Nitrification of added ammonium (NH/sub 4//sup +/) was inhibited following continuous exposure of soil to simulated acid rain of pH 4.1-3.2. The extent of the inhibition was directly related to the acidity of the simulated rain solutions. The production of inorganic N in the absence of added NH/sub 4//sup +/ was either stimulated or unaffected following continuous treatment of soils with pH 3.2 simulated acid rain. The addition of nitrapyrin (2-chloro-6-(trichloromethyl)pyridine), an inhibitor of autotrophic nitrification, caused a decrease in nitrification in water-treated soil but had little effect on nitrification in soil treated with pH 3.2 simulated acid rain. Intermittent applications of simulated acid rain (pH 3.5-4.1) for 19 weeks partially inhibited nitrate (NO/sub 3//sup -/) production in soil amended with NH/submore » 4//sup +/ following the exposure period, but NO/sub 3//sup -/ production in unamended soil was either unaffected or stimulated.« less

Effects of Heavy Metal and Other Elemental Additives to Activated Sludge on Growth of Eisenia foetida

Abstract: The approximate level at which added concentrations of certain elements would cause an activated sludge to induce a toxic effect upon the growth of Eisenia foetida was determined. During 43 trials on sludge samples obtained throughout 1 year of study, earthworms grew from 3 to 10 mg live wt at hatching to 792 mg +- 18% (mean +- C.V.) in 8 weeks, when sludge was 24/sup 0/C and contained no additives. None of several elements commonly used in microbial growth media enhanced the growth rate of the earthworm. At salt concentrations up to about 6.6% on a dry wt basis, none of six anions tested was in and of itself toxic, while five of 15 cations - Co, Hg, Cu, Ni, and Cd - appeared specifically to inhibit growth rate or cause death. Manganese, Cr, and Pb were innocuous even at the highest levels of application - 22,000, 46,000, and 52,000 mg/kg, respectively. Neither the anionic nor cationic component of certain salts, such as NaCl or NH/sub 4/Cl, could be said to inhibit growth, which occurred only at high concentrations of these salts (about 3.3 and/or 6.6%). Below 7 mmho/cm, toxicity could not be correlated with electrolytic conductance, though highermore » values may help to explain the nonspecific growth inhibitory effects of salts like NaCl and KCl. Nor could toxicity ever be ascribed to hydrogen ion activity, since sludge pH was not altered even at the highest salt dose. It is concluded that except under very extreme conditions, the levels of heavy metals and salts generally found in activated sludges will not have an adverse affect on the growth of E. foetida.« less

Chemical availability of cadmium in Mississippi River sediment

Abstract: There is concern that changes in the physiochemical conditions occurring during dredging and disposal of polluted sediments may increase chemical mobility and hence bioavailability of sediment-bound toxicants such as Cd. The objectives of this research were to study the chemical transformations of Cd in freshwater sediment as affected by pH and redox potential under controlled laboratory conditions and predict Cd behavior during dredging and disposal of Cd-contaminated sediments. Mississippi River sediment suspensions were incubated at four redox potential levels (-150, +50 +250, and +500 mV) at each of three pH levels (5.0, 6.5, and 8.0) and spiked with 0.2 ..mu..Ci carrier-free /sup 109/Cd/g solids. Sediment suspensions were sequentially extracted for easily mobile and potentially available /sup 109/Cd fractions. Essentially all of /sup 109/Cd extracted from alkaline sediment suspensions was associated with potentially available chelated, insoluble organic-bound and reducible fractions and was not affected by changes in oxidation-reduction conditions. A change from alkaline to acidic pH under moderately oxidized to well-oxidized conditions results in /sup 109/Cd transformations from potentially available organic forms to more mobile and readily available dissolved and exchangeable forms. This could create potential hazards of disposal of Cd-contaminated dredged sediments due to enhanced availability and leaching of Cdmore » as affected by altered physiochemical environments.« less