Arsenic solubility and distribution in poultry waste and long term amended soil

Arsenic solubility and distribution in poultry waste and long term amended soil

0048-9697/04/$ - see front matter 䊚 2003 Elsevier B.V All rights reserved.

doi:10.1016/S0048-9697(03)00441-8

Arsenic solubility and distribution in poultry waste and long-term

amended soil

F.X Hana,b,*, W.L Kingery , H.M Selim , P.D Gerard , M.S Cox , J.L Oldhama c d a a

Department of Plant and Soil Sciences, Mississippi State University, Mississippi State, MS 39762, USA

a

Diagnostic Instrumentation and Analysis Laboratory, Mississippi State University, 205 Research Blvd., Starkville, MS 39759,

b

USA Department of Agronomy, Louisiana State University, Baton Rouge, LA 70803, USA

c

Experimental Statistics Unit, Mississippi State University, Mississippi State, MS 39762, USA

d

Received 21 February 2003; accepted 15 July 2003

Abstract

The purpose of this study was to quantify the solubility and distribution of As among solid-phase components in poultry wastes and soils receiving long-term poultry waste applications Arsenic in the water-soluble, NaOCl-extractable (organically bound), NH OHØHCl-extractable (oxide bound) and residual fractions were quantified in an2 Upper Coastal Plain soil (Neshoba County, MS) that received annual waste applications After 25 years, As in the

amended soil had a mean of 8.4 mg kgy 1compared to 2.68 mg kgy 1for a non-amended soil Arsenic in the amended soil was mainly in the residual fraction(72% of total), which is generally considered the least bioavailable fraction

Arsenic in poultry waste samples was primarily water-soluble(5.3–25.1 mg kg ), representing 36–75% of the totaly 1

As To assess the extent of spatial heterogeneity, total As in a 0.5-ha area within the long-term waste-amended field was quantified Soil surface samples were taken on 10-m grid points and results for total As appeared negatively skewed and approximated a bimodal distribution Total As in the amended soil was strongly correlated with Fe oxides, clay and hydroxy interlayered vermiculite concentrations, and negatively correlated with Mehlich III-P, mica and quartz contents

䊚 2003 Elsevier B.V All rights reserved

Keywords: Arsenic; Poultry waste; Fractionation; Solubility; Spatial distribution

1 Introduction

Arsenic(As) has become an increasingly

impor-tant environmental concern due to its potential

carcinogenic properties (Goyer et al., 1995)

Recently, the USEPA announced a decrease in the

allowable As level for drinking water from 50 to

*Corresponding author Tel.: 662-325-2897; fax:

q1-662-325-8465.

E-mail address: han@dial.msstate.edu(F.X Han).

10 mg ly 1 (USEPA, 2001) Arsenic is added to

poultry diets for the control of coccidial intestinal parasites and to improve feed efficiency (Moore

et al., 1995; Wershaw et al., 1999) The

organo-arsenical compounds, p-arsanilic acid

(3-nitro-hydroxyphenylarsonic acid), are typical

feed additives(Wershaw et al., 1999; Jackson and

Miller, 2000) Because these compounds are not

readily absorbed in tissues, they can occur in

excreta Therefore, the As in poultry wastes and

waste-amended soils may be present primarily in

organic forms (Morrison, 1969; Woolson, 1975)

Moore et al (1998) found that As concentrations

in runoff from poultry-waste-amended soils

increased as application rates increased In

addi-tion, because long-term applications to relatively

small areas of land have been shown to lead to

soil accumulation of nutrients and trace elements

(Kingery et al., 1994; Han et al., 2000), the study

of As behavior in waste-amended soil systems is

crucial due to potential contamination of surface

and groundwater via runoff and leaching

Several studies have documented As speciation

and toxicity in soils (Onken and Hossner, 1995;

Cox et al., 1996a) The bioavailability, toxicity

and mobility of As in soil–water–plant systems

are largely determined by its speciation and

distri-bution, or partitioning between the solution and

soil matrix Moreover, As mobility and possible

release into runoff from waste-amended fields may

be governed by its distribution among various soil

solid-phase components Arsenic distribution

among solid-phase components in poultry waste

and in waste-amended soils is not well understood

Sequential dissolutionyextraction techniques, as

opposed to a single extractant, have recently been

adopted as indicators for As binding, mobility and

bioavailability(Wenzel et al., 2001) Since As has

similar physicochemical properties to P in soils,

inorganic P fractionation techniques have been

adapted for soil As (Johnston and Barnard, 1979;

Onken and Adriano, 1997) Moore et al (1988)

divided As in sediments into oxyhydroxide (Fe

and Mn)-bound, organically bound and

sulfide-bound fractions Recently, Wenzel et al (2001)

proposed a fractionation procedure that included

non-specifically adsorbed, specifically sorbed,

amorphous and poorly crystalline Fe and Al

oxides-bound, crystalline Fe and Al hydrous

oxides-bound and residual fractions Since the

main species of As in poultry waste is as an

organic compound, about which little is know

concerning its binding by solid phases, it is

appro-priate to include an extractant for organic matter

(OM)

The primary objective of this study was to

determine the solubility and distribution of As

among solid-phase components in poultry waste and waste-amended soils receiving long-term applications A second objective was to correlate soil properties to the spatial distribution of As in

a long-term amended soil

2 Materials and methods

2.1 Poultry-waste-amended soil and poultry wastes

Six soil samples(0–20 cm) were taken from a

waste-amended pasture on a poultry farm located

in Neshoba County, Mississippi, where annual applications had occurred for 25 years Although historical records of application rates are not com-plete, recent measurements of typical application management indicate that rates were approximately

10 Mg hay 1 per application, one to three times each year (Curtis, 1998) The pasture consisted

predominantly of bermudagrass (Cynodon

dacty-lon) harvested for hay each summer and ryegrass

(Lolium multiflorum) sown each fall, after shallow

plowing Cattle grazed during the winter months

In order to assess the spatial variation of As resulting from the long-term poultry waste amend-ments, surface soil samples were collected on a grid from the waste-amended field Specifically,

66 surface samples (0- to 5-cm depth) from the

waste-amended field were sampled at 10-m inter-vals on a 50=100 m grid, located in the center2

of the field In addition, surface (0–5 cm) soil

samples were collected from an adjacent, non-amended forest soil where loblolly pine (Pinus

taeda) grew Both soils were clayey, mixed,

ther-mic Typic Hapludults(Upper Coastal Plain) from

shale parent material Properties of both soils were reported earlier in Han et al (2000) Soil pH

ranged from 4.7 to 6.3 The amended soil had higher pH, OM and CEC than the non-amended soil(Table 1) (Curtis, 1998)

Soil samples were air-dried and ground to pass

a 2-mm sieve All soil samples were analyzed for total As Furthermore, we carried out analysis for water-soluble As in 10 randomly selected surface samples from our grid scheme

Poultry waste samples were collected from two locations(Marshall and Newton counties) in

Mis-Table 1

Selected properties of the non-amended and poultry-waste-amended surface soils

CEC (cmol kg ) y 1

Mineralogy of the clay fraction (%) b

Mean of five samples and standard error.

a

From Ref Curtis (1998).

b

Table 2

Total and water-soluble As concentrations in poultry wastes on oven-dry basis

Summary

Average followed by standard deviation in parentheses.

sissippi between 1997 and 2000(Table 2) In 1999

and 2000, multiple, composite waste samples were

collected throughout the year The samples were

air-dried and ground to pass a 1-mm sieve

Solid-phase As fractionation was conducted on 10

sam-ples This study focused on overall As solubility

and its solid-phase distribution in both poultry

wastes and long-term waste-amended soils, and no attempt was made to differentiate arsenate and arsenite forms

2.2 Analytical methods

Arsenic in soils and poultry wastes was meas-ured in four operationally defined solid-phase

frac-tions, which were obtained by selective sequential

dissolution This method is based on both

solubil-ity of individual solid-phase components and the

selectivity and specificity of chemical reagents

The procedure provides a gradient for the

physi-cochemical association between trace elements and

solid particles rather than actual chemical

specia-tion (Martin et al., 1987) But, it can nonetheless

provide an indication of their relative availability

to plants or to further migration with percolating

andyor runoff water The terms of all fractions are

more appropriately considered to be operationally

rather than chemically defined (Han et al., 2001)

Each extractant in the sequential selective

proce-dures is assumed to effectively target one major

solid-phase component It is recognized that no

extractant can remove all of a targeted solid-phase

component without attacking other components

No selective dissolution scheme can be considered

completely accurate in distinguishing between

dif-ferent forms of an element, i.e various organic

inorganic solid-phase components Despite

possi-ble re-adsorption during sequential extraction,

common to any chemical extraction procedure,

sequential dissolution techniques still furnish

use-ful information on metal binding, mobility and

availability (Han et al., 2001) The fractionation

procedures employed in this study were modified

from the sequential selective procedures developed

by MacLeod et al.(1998), Shuman (1983), Moore

et al.(1998) and Sposito et al (1982) Arsenic in

both waste-amended soil and wastes was

fraction-ated into water-soluble, NaOCl-extractable,

NH OHØHCl-extractable and residual fractions2 (4

M HNO3)

(1) Water-soluble arsenic: Twenty milliliter of

distilled water was added to 2 g of soil or waste

(oven-dry weight basis) in 50-ml Teflon centrifuge

tube and the mixture was shaken for 30 min at 25

8C The sample was then centrifuged at 10 000=g

and the supernatant decanted and filtered through

a 0.45-mm filter The soil residue was kept for the

subsequent extraction The same centrifugation–

decantion steps were used after each of the

follow-ing extractions

(2) NaOCl-extractable arsenic: Arsenic

extract-ed in this way may be mainly bound to OM

(Shuman, 1983) Twenty milliliter of 0.7 M NaOCl

solution at pH 8.5 (pH adjusted with NaOH and

HCl) was added to the soil residue The mixture

was boiled in a water-bath at 95–100 8C for 30 min During digestion, the mixture was continu-ously stirred

(3) NH OHØHCl-extractable arsenic: Arsenic 2

extracted in this step may be mostly bound to oxides (Han and Banin, 1997): Twenty milliliter

of 0.04 M NH OHØHClq25% HOAc solution was2 added to the soil residue and boiled in the water-bath at 100 8C for 3 h

(4) Arsenic in the residual fraction (RES):

Twenty milliliter of 4 M HNO solution was added3

to the residue and the sample transferred to a glass digestion tube Digestion was conducted in a water-bath at 80 8C for 16 h (Sposito et al., 1982; Han

and Banin, 1997) This fraction includes As that

was not extracted in the previous steps and repre-sents the very stable fraction in soil and wastes Total As was extracted with heating with HNO –H SO3 2 4(Ganje and Rains, 1982) Amended

and non-amended soils were analyzed both by Galbraith Laboratory(Knoxville, TN) and

Missis-sippi State Chemical Laboratory (Mississippi

State, MS) for total As concentrations The results

from the two laboratories were very consistent A large number of samples were analyzed by Missis-sippi State Chemical Laboratory Arsenic concen-trations in the extracts were determined using graphite furnace atomic absorption spectroscopy

(GFAAS) (Perkin Elmer, Norwalk, CT) at 193.7

nm wavelength with background correction A mixed matrix modifier containing 0.015-mg Pd and 0.01-mg Mg(NO ) was used for each 20-ml3 2 standard or sample solution(Perkin Elmer, 1995)

Arsenic concentration in each soilywaste sample

was analyzed in duplicate

Due to perceived relationship between P and As mobility(Peryea, 1991), Mehlich III-extractable P

was also determined (Mehlich, 1982) Organic

carbon in soils was measured by wet combustion

(Nelson and Sommers, 1982) Iron oxides were

extracted by citrate-dithionate-bicarbonate(Dixon

and White, 1997) and the Fe was determined by

atomic absorption spectroscopy Soil pH was meas-ured in 1:1 soilywater ratio using a combination

glass pH electrode Particle size distribution was determined with a hydrometer(Day, 1965)

2.3 Mineralogical analyses

Quantitative analyses of minerals in clay

frac-tion of soils were determined following the

meth-ods of Karathanasis and Hajek (1982) and

Karathanasis and Harris (1994) Samples were

pretreated to remove salts, carbonates, OM and Fe

oxides, and the fine clay-sized fraction(-0.2 mm)

was collected by sieving and centrifugation

(Jack-son, 1956; Dixon and White, 1997) Clays were

saturated with Mg and K by washing with 1 M

MgCl2 or KCl, respectively The Mg-clay was

solvated with glycerol, and the K-clay was

sequen-tially heated to 300 and 500 8C for 4 h before

analysis by X-ray diffraction (XRD) A Philips

X’Pert-MPD PW 3050 diffractometer (Philips

Electronics, Almelo, The Netherlands) equipped

with a ceramic long, fine focus copper anode tube

was used for XRD analysis Samples were

step-scanned from 28 to 308 2u at 1 s per step with a

step size of 0.038 2u Differential scanning

calor-imetric (DSC) analysis (DSC 910S, TA

Instru-ments Inc., New Castle, DE) was conducted on

the Mg-clays that had been equilibrated at 54%

relative humidity Magnesium-clay was first cooled

to 5 8C, and then heated in covered aluminum

pans from 5 to 625 8C at 10 8C miny 1 in N

2 atmosphere An empty, covered aluminum pan was

used as the reference (Karathanasis and Harris,

1994)

2.4 Correlation analysis

Pearson Product Moment correlation coefficients

were calculated using available software (SAS

Institute Inc., 1989) for all pairs of variables: pH,

organic carbon, Fe oxide, particle size distribution,

Mehlich III-P concentrations, total As

concentra-tions and clay mineralogical composition The

effects of soil properties on As accumulation in

the amended field were estimated

3 Results and discussion

3.1 Arsenic in amended soil and poultry wastes

Total as well as water-soluble As in poultry

waste samples are presented in Table 2 Total As

in poultry wastes ranged from 11.1 to 36.2

mg kgy 1 with an average of 26.9 mg kgy 1 The

As concentrations in more than 50% of the samples analyzed were between 30 and 35 mg kgy 1, which were similar to As ranges reported by Moore et

al.(1995) Total As varied with sampling location

and time (Table 2) We sampled poultry waste

from Marshall county, Mississippi, from 1997 to

2000 and found that As concentrations in 2000 were smaller than that in 1997 and 1998 As a comparison, As concentrations in all samples of waste were less than the permitted monthly aver-age concentration of 41 mgAs kgy 1for land appli-cation of sewage sludge(USEPA, 1994)

Solubility of As in poultry waste, indicated here

by water-soluble As, is linked to its mobility and toxicity in soilywater systems Water-soluble As

concentrations in wastes varied from 5.3 to 25.1

mg kgy 1 with an average of 15 mg kgy 1 over the period samples were collected (Table 2) This As

accounted for 36–75% of measured total As(Table

2) Some 35% of the samples were in the range

of 20–25 mg kgy 1 of water-soluble As There was also large variation in As concentrations among sites and among years of sampling (Table 2) In

addition, water-soluble As concentrations in the wastes were correlated (r s0.78, P-0.05) with2 total As (Fig 1) Jackson et al (2000) reported

that most water-soluble As was in organo-arsenical forms, such asp-arsanilic acid and roxarsone.

In the 10 poultry waste samples used for frac-tionation analysis, As in the water-soluble fraction was the largest fraction with an average of 47%, followed by the NH OHØHCl-extractable fraction,2 which represented 33% of the total (Fig 2) The

NaOCl-extractable As made up 13% and the resid-ual fraction accounted for 7% of the total As(Fig

2) The high solubility of As in poultry waste may

be due to a large portion of it existing as organic species, and lack of solid-phase components, such

as Fe oxides, with high binding affinity for As It has been shown that incorporation of alum into poultry-house bedding materials significantly decreases soluble As concentrations in poultry wastes and in runoff from amended soils(Sims et

al., 2001; Moore et al., 1998)

Arsenic accumulation in surface soils(0–5 cm)

over approximately 25 years of poultry waste

Fig 1 Water-soluble vs total As concentrations in poultry waste samples.

applications is indicated by the results given in

Table 3 Total As concentration in the amended

soil ranged from 1.7 to 15.2 mg kgy 1 with an

average of 8.4 mg kgy 1 By comparison, total As

in the non-amended soils was from 0.59 to 4.5

mg kgy 1 and averaged 2.68 mg kgy 1 with a

stan-dard deviation of 1.35 mg kgy 1 Thus, total As in

the amended soil was four times greater than that

in the adjacent non-amended soils If we assume

recent application rates of 10 Mg hay 1 per

appli-cation and two appliappli-cations per year over the

history of the field (Curtis, 1998), As input is

estimated to be 5.3 mgAs kgy 1 in the surface soil

(0–20 cm) In other words, the average As input

rate was approximately 0.54 kgAs hay 1yry 1,

which is equivalent to 0.21 mgAs kgy 1yry 1in the

top 20 cm of soil This suggests that annual As

loading at current application rates is below the

annual ceiling rates (2.0 kgAs hay 1yry 1) for safe

land application of sewage sludge(USEPA, 1994)

It should be noted, however, that this field was

plowed annually and therefore subject to a

rela-tively high degree of erosion This practice is

typical for the region Removal of As by eroded

soil particles is unknown

Arsenic in the long-term waste-amended soils

was mostly present in the residual fraction(72%),

followed by NH OHØHCl-extractable2 fraction

(21%) and NaOCl-extractable fraction (6%) (Fig

2) Compared to As distribution in poultry wastes,

As in the long-term amended soil appears to be in more stable forms, resulting in decreased As bio-availability and mobility This indicates that pos-sible quick leaching of water-soluble As into surface water probably occurs shortly after wastes are applied to fields Jackson and Miller (2000)

have shown that aryl-organoarsenical compounds are well adsorbed on amorphous Fe oxides and on goethite Arsenic is known to become rapidly recalcitrant in soil with time after application

(Onken and Adriano, 1997) At present there are

no detailed studies on As distribution in poultry wastes and poultry-waste-amended soils available

in the literature However, studies on As solid-phase fractionation in soils that received long-term pesticide applications showed oxide-bound As to

be the dominant fraction It was reported that oxyhydroxides of Fe, Al, Mn are the primary solid phases influencing soil As solubility(Woolson et

al., 1971; Johnston and Barnard, 1979; Livesey and Huang, 1981) However, the present study

indicates that in addition to Fe-oxide-bound As, the residual As is a major solid-phase fraction in amended soils

3.2 Spatial heterogeneity

Results of spatial measurements of total As in the waste-amended field indicate extensive

hetero-Fig 2 Comparisons of distributions of As among solid-phase components in poultry waste and long-term poultry-waste-amended soil.

Table 3

Total As concentrations and As fractionation in poultry wastes and the surface layer of a long-term poultry-waste-amended and a non-amended soil

(cm)

(mg kg ) y 1

n, sample number.

a

geneity This is illustrated in Fig 3 where the

lowest values were in the northeast section and

the highest values of As tended to be in the

southwest section of the field On the basis of the

coefficient of variation (CV), a high degree of

variability in As concentrations was observed

Reasons for this variability are not obvious and

reflect non-uniformity of waste applications, soil

adsorption–desorption properties for As, plant

uptake, slopes and others The CV is consistent with that of soil Cd measured by Murray and Baker (1992) of 91.5% This indicates that trace

element concentrations in field soils are highly variable Test for normality using frequency distri-butions and the Kologorov–Smirnov D-statistic suggested that As concentrations were not

normal-ly distributed Such finding has been reported by others For example, Murray and Baker (1992)

Fig 3 Spatial distribution of total As (mg kg ) in surface soils of a long-term poultry-waste-amended field The water flows of y 1 two small streams were indicated as arrows.

showed that total Cd concentrations taken on a

15.2=15.2 m grid from a 2.1-ha site were nega-2

tively skewed and approximated a lognormal

dis-tribution A histogram of As concentrations from

our waste-amended field is shown in Fig 4 It

suggests that As distribution is somewhat

nega-tively skewed with an apparent bimodal

distribu-tion We are not aware of such distributions for

heavy metal observations at the field scale If

spatial analysis of As data shown in Fig 3 is

desired, such as in ordinary kriging, variogram

analysis of the data is necessary Semi-variogram

analysis(not shown) exhibited a gradual increase

and then leveling off and reaching a sill after four separation distances or lags

3.3 Correlation with soil properties

Total As concentrations in

poultry-waste-amend-ed surface soils were positively correlatpoultry-waste-amend-ed with clay content, Fe oxide and hydroxy-interlayer ver-miculite content, and negatively correlated with mica, quartz, silt and Mehlich III-P concentrations

(Table 4) In the clay fraction, hydroxy

interlay-Fig 4 Frequency distribution of total As in a 0.5-ha site within a long-term poultry-waste-amended field.

Table 4

Correlation analyses of total As concentrations with selected soil properties and clay mineral composition in the clay fraction(ns

60 ) of poultry-waste-amended field

Properties As pH Organic Fe O2 3 Clay Silt Sand PMehlich HIV Kaol Mica

Organic carbon 0.18 0.28 *

Fe O2 3 0.64 * 0.22 0.39 *

Silt y 0.35 * y 0.09 y 0.49 * y 0.40 * y 0.69 *

Sand y 0.20 y 0.10 y 0.04 y 0.25 * y 0.17 y 0.59 *

Mehlich y 0.31 * 0.07 y 0.04 y 0.23 y 0.15 0.21 y 0.11

HIV 0.34 * 0.21 0.30 * 0.39 * 0.51 * y 0.37 * y 0.08 y 0.02

Mica y 0.52 * y 0.06 y 0.35 * y 0.47 * y 0.61 * 0.72 * y 0.29 * 0.42 * y 0.52 * y 0.27 * Quartz y 0.52 * y 0.20 y 0.42 * y 0.53 * y 0.58 * 0.62 * y 0.18 0.43 * y 0.45 * 0.09 0.70 *

P , HIV and Kaol represent Mehlich P in the soils, and HIV and kaolinite in the clay fraction, respectively.

a

Mehlich III

Correlation is significant atP-0.05 level.

*

ered vermiculite (HIV) was the major mineral,

followed by kaolinite and mica(Curtis, 1998, data

not shown) These correlations suggest that more

As may accumulate in soils with higher clay

contents

Total As was negatively correlated with Mehlich

III-extractable P in the poultry-waste-amended soil

(Table 4) Enhanced As mobility, phytoavailability

and phytotoxicity were reported in lead

arsenate-contaminated soils amended with monoammonium

phosphate(Peryea, 1991) Arsenic is adsorbed on

soil mineral surfaces through ligand exchange with surface hydroxide or hydrated metal-oxide miner-als (Goldberg, 1986) Phosphate and AsO3y

4 exhibit similar physicochemical behavior in soils and compete directly for specific adsorption sites

in soil particles (Hingston et al., 1972; Woolson,

1983) Total P in the poultry-waste-amended

sur-face soil was 2000 mg kgy 1 and Mehlich III-P was 500 mg kgy 1 (Curtis, 1998) Thus, As

solu-bility and mosolu-bility in both waste and waste-amended soils may be enhanced by these high

concentrations of P Similarly, Cox et al (1996b)

showed that addition of As increased solution P

concentrations in the soil

4 Conclusions

At the current application rates, arsenic

accu-mulated over 25 years of poultry waste

applica-tions is estimated at 5.9 mgAs kgy 1 in the surface

20 cm or with an input rate of approximately 0.54

kgAs hay 1yry 1 This annual As loading is much

lower than the rates established by USEPA for

land application of sewage sludge Moreover,

arsenic in the amended soil was mainly in the

residual fraction(72% of total), which is the least

susceptible fraction to runoff losses as soluble As

or downward movement However, since As in the

applied poultry waste was primarily water-soluble

(5.3–26 mg kg ), representing 36–75% of totaly 1

As, an excessive application of poultry wastes per

time could release soluble As from amended fields

Assessment of the extent of spatial heterogeneity

revealed that distribution of total As in the

amend-ed soil appearamend-ed negatively skewamend-ed and

approxi-mated a bimodal distribution We also found that

total As in the amended soil was strongly

corre-lated with Fe oxide, clay and HIV concentrations,

and negatively correlated with Mehlich III-P, mica

and quartz contents

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