Society for American Archaeology

The Quantitative Analysis of Soil PhosphateAuthor(s): William I. WoodsSource: American Antiquity, Vol. 42, No. 2 (Apr., 1977), pp. 248-252Published by: Society for American ArchaeologyStable URL: http://www.jstor.org/stable/278986 .Accessed: 29/06/2011 14:06

Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unlessyou have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and youmay use content in the JSTOR archive only for your personal, non-commercial use.

Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at .http://www.jstor.org/action/showPublisher?publisherCode=sam. .

Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printedpage of such transmission.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.

Society for American Archaeology is collaborating with JSTOR to digitize, preserve and extend access toAmerican Antiquity.

http://www.jstor.org

248 AMERICAN ANTIQUITY [Vol. 42, No. 2, 1977]

ments, and rock cairns found at ridge-back sites; however, flaked stone materials of other traditions are also associated in some cases, making it impossible now to demonstrate the association of ridge-backs and stone features.

A few ridge-backs could be fortuitous, but the great quantity and similarity of both large and small specimens at the site locations strong- ly suggests that they are man-made.

It is hoped that other investigators will recognize this lithic tradition elsewhere as more archaeologists become familiar with the unusual form and the knapping techniques involved.

Acknowledgments. My thanks to George F. Carter of Texas A & M University for his encouragement and assistance in preparing this paper. I am also grateful to Alan Bryan and Frank E. Poirier for critically review- ing this paper and to Donald Crabtree for his valued comments and suggestions that inspired this study.

Finally without the assistance and understanding of my wife, Lucille Childers, none of this work could have been possible. The photos are by G. J. Bianchi and the graphics are by Jaime Servin.

Bischoff, James L., and others 1976 Antiquity of man in America indicated by

radiometric dates on the Yuha burial site. Nature 261:28-29.

Carter, George F. 1957 Pleistocene man in San Diego. Johns

Hopkins University Press, Baltimore. Childers, W. Morlin

1974 Preliminary report on the Yuha burial, California. Anthropological Journal of Canada 12(1):2-9.

Rogers, Malcolm J. 1929 Early lithic industries of the lower basin of

the Colorado River and adjacent desert areas. San Diego Museum Papers 3:16-22.

1966 Ancient hunters of the Far West. The Union Tribune Publishing Company, San Diego.

Weismeyer, Albert L., Jr. 1968 Geology of the northern portions of the

Seventeen Palms and Fonts Point Quadrangles Imperial and San Diego Counties, California. Unpublished M.A. thesis, Department of Geology, University of Southern California.

Woodring, W. P. 1935 Distribution and age of the Tertiary

deposits of the Colorado desert. Carnegie In- stitution of Washington Publication 148:11-25.

THE QUANTITATIVE ANALYSIS OF SOIL PHOSPHATE

WILLIAM I. WOODS

Developments in environmental quality testing have revealed the need for a reappraisal of the methods of phosphate determination employed by archaeologists. The results of such a reappraisal are presented with recommendations for the implementation of a new technique of quantitative phosphate determination called sequential fractionation. With this technique three discrete fractions are determined by differential solubility criteria. These fractions closely approximate in amount the major types of inorganic phosphate known to be retained by soils. Sample analyses are presented which indicate that the method can be employed to distinguish between natural and human deposited phosphate and to identify features.

Soil chemical changes resulting from human occupation have relatively recently become a topic of abandoned settlement studies. Soil chemistry is altered directly through the deposi- tion and decay of organic and inorganic debris. On the microscale, settlement soils exhibit pH anomalies and often, greatly increased con- centrations of different compounds of calcium, nitrogen, carbon, phosphorus, and certain trace metals. Phosphorus compounds in the form of phosphate have proved to be the most stable in their chemistry and location in a wide variety of soils.

During the past three years, the author has been involved in a project part of whose purpose has been the development of ap- propriate field and laboratory methods for the

analysis of phosphate in settlement soils (anthrosols). The study has produced an inex- pensive, versatile field method for detection of phosphate which presently is being widely employed (Eidt 1973; Woods 1975). In addi- tion, through modifications of phosphate frac- tionation schemes devised for pedogenic in- vestigations, a quantitative procedure has been developed by means of which highly accurate determinations of discrete chemical forms of inorganic phosphate in soils from abandoned settlements have been achieved for the first time.

It has become apparent that with certain exceptions, the field method is extremely worthwhile in site surveys (for example, see Gregg 1975: 184-87). Present evidence indicates

REPORTS 249

that the method can be most helpful in reconstructing regional settlement geographies and in the location and delimitation of in- dividual settlements. It is anticipated that at a larger scale of inquiry, the study of phosphate distributions will reveal house types, field forms, and the form and function of areas and structures within settlements.

Though sites can be located with the qualita- tive field test, quantitative analysis techniques are necessary to ascertain the kinds and amounts of phosphate involved. Once the latter are known, conclusions about the intensity and duration of habitation can be drawn, accurate phosphate maps compiled, and comparisons between intersite and intrasite elements within regional contexts made.

Archaeologists and geographers who have become interested in the measurement of human phosphate depositions have either sent samples outside for analysis or borrowed analytical techniques directly from agronomy, and, in many cases, have employed unmodified procedures without a firm understanding of the principles involved. Numerous laboratory procedures for phosphate determination have been employed by abandoned settlement in- vestigators. Various researchers have used agronomic techniques designed for testing avail- able phosphate concentrations (Arrhenius 1931; Lorch 1940; Lutz 1951; Solecki 1951; Dietz 1956; Eddy and Dregne 1964; and Abt 1968). Unfortunately, the results of these methods could be highly misleading as available phosphate constitutes only a small part of total soil inorganic phosphate and can vary signifi- cantly in amount from season to season. When soils are sent to outside laboratories for analy- sis, available phosphate tests are the only ones routinely carried out.

Procedures with a strong acid extraction are more reliable (Buehrer 1950; Lorch 1954; Cornwall 1958). Though adequate for deter- mining the amounts of calcium oriented phosphate, acid extractions do not work well with the iron oxide occluded phosphate found in some acid soils, and only a little better for determining the nonoccluded phosphate as- sociated with aluminum and iron compounds. Total phosphate determinations produce a com- bined inorganic/organic result, but still tell little about the nature of the phosphate beyond its absolute amount. Unlike those who have relied

on the above single extraction procedures, only Mattingly and Williams (1962) have examined more than one type of phosphate. These two soil scientists were able to test for total, available, and organic phosphate in a soil from a Roman site in England. Of the methods used in the phosphate analysis of anthrosols, it has become increasingly clear that the recently developed fractionation procedure is the most revealing.

The technique is based upon the differential solubility of the major phosphate forms in various extracting solutions (Chang and Jackson 1957; Syers et al. 1972). When these solutions are arranged in appropriate sequence, the procedure can yield results which are specific as to phosphate form (Fig. 1). Readily carried out by students with even minimal chemical back- grounds, the technique could be adequately performed in many laboratories of the type commonly found associated with anthropology and geography departments. Detailed procedural instructions and equipment needs can be found in a recent publication (Eidt and Woods 1974:79-103, 146-55).

To illustrate some of the conclusions which can be drawn from fractionation analysis, six sample results are presented in Table 1. The total amount of inorganic phosphate is reported in parts per million elemental phosphorus (ppm P). Totals for extractions are shown in percentage figures. Figures in the NaOH&CB column closely approximate the amount of nonoccluded aluminum and iron phosphate found in each sample. In the same manner, the CBD column reflects the quantity of occluded aluminum and iron phosphate, whereas the HCI column shows phosphate found to be in com- bination with calcium. The samples were chosen to reflect varying degrees of human influence.

Sample 1 was taken from one of a group of burials found under a medieval church floor. Due to the dryness of the soil and to the permanent floor covering, the body experi- enced little weathering. As a result, mineraliza- tion of organic matter and slight bone dis- integration were the only evident effects of the last several hundred years since interment. The total column shows the extremely high phosphate concentrations which are found in conjunction with burials.

The moderately high concentration and fair-

250 AMERICAN ANTIQUITY [Vol. 42, No. 2, 1977]

1.0g AIR DRIED SOIL SAM PLE

40 ml 0 1 N NaOH/1 0 N NaCI

12 hr SHAKING/CENTRIFUGE

SOLUTION A

NaOH 1 0 N NaCI WASH TWICE/CENTRIFUGE/DISCARD

50 tmil Na CITRATE/Na BICARBONATE

15 min WATER BATH 85? C/CENTRIFUGE

25 ml NaCI WASH/CENTRIFUGE

SOLUTION B SOIL

NaCI WASH TWICE/CENTRIFUGE/DISCARD | 1 50 ml Na CITRATE/Na BICARBONATE | I 1Og 0 g Na DITHIONITE

I I I 15 min WATER BATH 85? C/CENTRIFUGE

i | _ 25 ml NaCI WASH/CENTRIFUGE

| SOLUTION C SOI

1 (CBD) |NaCI WASH/CENTRIFUGE/DISCARD

40 ml 1 0 N HCI

4 hr SHAKING/CENTRIFUGE

SOLUTION D SOIL | 1 11 | t~~~~~~~~~~~~~HCI)

I I (HCI) ~~~~~~~~~~~~(DISCARD)

NON-OCCLUDED P SORBED FOCCLUDED Al- & Fe-P ACID EXTRACTABLE Al - & Fe-P DURING (OCCLUDED AND

PREVIOUS EXTRACTION SOME LATTICE) Ca -P

DETERMINED DETERMINED DETERMINED DETERMINED BY METHOD 1' BY METHOD 2- BY METHOD 2" BY METHOD 1'

'Method 1 is the colorimetric technique of Murphy and Riley, 1962.

'-Method 2 is a modification of the isobutyl alcohol procedure of Berenblum and Chain, 1938.

Fig. 1. Flow sheet for soil inorganic phosphate fractionation system (Eidt and Woods 1974:75).

ly even relative distribution among the discrete fractions of sample 2 are representative of phosphate from residential areas. In contrast is sample 3, also from within the settlement area and collected only 75 meters away. However, it is from a ceremonial, rather than a residential zone. This conclusion is supported by both the phosphate distribution and concentration in the fractions. Though exhibiting some human inter-

ference, the results are much closer to what one might expect from the moderately weathered, slightly acid soils found naturally in the area.

The phosphate distribution and concentra- tion shown with sample 4 reveal that even modern agricultural fertilization activities pre- sent few problems of interpretation. In addition to being trapped within the plow zone, applied phosphate concentrations rarely even approach

REPORTS 251

Table 1. Inorganic Phosphate Fractionation Results

NaOH & CB CBD HC1 Total

1. Medieval burial 40% 22% 38% 2984ppm P

2. Aboriginal residential 37% 30% 33% 833

3. Aboriginal ceremonial 48% 42% 10% 165

4. Modern fertilized field 25% 22% 53% 195

5. Diatomaceous clay 4% 3% 93% 378

6. Marl deposit 3% 4% 93% 302

those found to be associated with habitation activities.

It is to be emphasized that the last two samples reveal relatively high phosphate con- centrations which could, if one were using only a field test or single fraction procedure, be mistaken as those of an anthrosol. Only the fractionation system shows the distribution of phosphate forms within soils of this kind. When the majority of the phosphate is found in only one fraction, it reveals a lack of human influ- ence on the distribution. By contrast, numerous tests on soils from tropical to boreal conditions have shown that the phosphate associated with human settlements is found distributed in varying degrees throughout all three fractions.

In summary, of the types of evidence avail- able for study at abandoned settlements, physical and chemical soil changes induced by human occupation are among the most lasting and potentially valuable. Especially important to settlement soil studies are those tests which reveal phosphate depositions of human origin. Recently, field and laboratory techniques have been developed specifically for the analysis of phosphate in anthrosols. Through a quantitative laboratory method called sequential fractiona- tion, human phosphate depositions can be distinguished from natural ones and types of features and land use can be identified. It is hoped that through the testing of selected samples from a variety of cultural and temporal contexts, the mechanisms affecting phosphate accumulations in soils at settlements can be clarified and that the field and laboratory applications of the new techniques will he expanded.

Acknowledgments. The direction and help of Robert C. Eidt through all phases of the project are gratefully acknowledged. In addition, I wish to thank Clinton R. Edwards and Melvin L. Fowler for their advice and encouragement, and the University of Wisconsin-Milwaukee Graduate School and the Depart- ment of Geography for providing support.

Apt, Peter 1968 Phosphatuntersuchungen zur topo-

graphischen Lokalisation von Ortswustungen. Geographica Helvetica 6:185-90.

Arrhenius, 0. 1931 Die Bodenanalyse im Dienst der

Archaologie. Zeitschrift fur Pflanzenerndhrung, Diingung, und Bodenkunde 10:427-39.

Berenblum, O., and E. Chain 1938 An improved method for the colorimetric

determination of phosphate. Biochemical Journal 32:295-98.

Buehrer, T. F. 1950 Chemical study of the material from several

horizons of the Ventana Cave profile. In The stratigraphy and archaeology of Ventana Cave, Arizona, by Emil W. Haury and others, pp. 549-63. The University of Arizona Press, Tucson.

Chang, S. C., and M. L. Jackson 1957 Fractionation of soil phosphorus. Soil

Science 84:133-44. Comwall, I. W.

1958 Soils for the archaeologist. Phoenix House, London.

Cruxent, J. M. 1962 Phosphorus content of the Texas street

"hearths." American Antiquity 28:90-91. Davidson, D. A.

1973 Particle size and phosphate analysis: evi- dence for the evolution of a tell. Archaeometry 15:143-52.

Dietz, Eugene F. 1957 Phosphorus accumulation in soil of an

Indian habitation site. American Antiquity 22: 405-09.

252 AMERICAN ANTIQUITY [Vol. 42, No. 2, 1977]

Eddy, F. W., and H. E. Dregne 1964 Soil tests on alluvial and archaeological

deposits, Navajo Reservoir district. El Palacio 71:5-21.

Eidt, R. C. 1973 A rapid chemical field test for archaeologi-

cal site surveying. American Antiquity 38: 206-10.

Eidt, Robert C., and William I. Woods 1974 Abandoned settlement analysis: theory and

practice. Field Test Associates, Milwaukee. Gregg, Michael L.

1975 Test excavation at two sites in northwestern Illinois. The Wisconsin Archeologist 56: 174-200.

Lorch, Walter 1940 Die siedlungsgeographische Phosphat-

methode. Die Naturwissenschaften 28:633-40. 1954 Die anthropogenen Bodenphosphate des

Hohenstaufen-Gipfels. Jahrbucher fur Statistik und Landeskunde von Baden- Wiirttemberg 1: 367-75.

Lutz, H. J. 1951 The concentration of certain chemical ele-

ments in the soils of Alaskan archaeological sites. A merican Journal of Science 249:925-28.

Mattingly, S. E. G., and R. J. B. Williams 1962 A note on the chemical analysis of a soil

buried since Roman times. Journal of Soil Science 13:254:58.

Murphy, J., and J. P. Riley 1962 A modified single solution method for the

determination of phosphate in natural waters. Analytica ChimicaActa 27:31-36.

Solecki, Ralph S. 1951 Notes on soil analysis and archaeology.

American Antiquity 16:254-56.

Syers, J. K., G. W. Smillie, and J. D. H. Williams 1972 Calcium fluoride formation during extrac-

tion of calcareous soils with fluoride: I. implica- tions to inorganic P fractionation schemes. Soil Science Society of America Proceedings 36: 20-25.

Woods, William I. 1975 The analysis of abandoned settlements by a

new phosphate field test method. The Chesopiean 13:1-45.

ULTRASONIC DISAGGREGATION OF POTSHERDS FOR MINERAL SEPARATION AND ANALYSIS

ALAN M. GAINES JULIA L. HANDY

Weakly bound composite materials such as low-fired pottery, bricks, mortar, and indurated soils can be disaggregated by ultrasound with no significant chemical or physical alteration of individual component grains. The components may then be separated by size, shape, density, magnetic properties, etc. This allows mineralogical, bulk chemical, trace-element, thermoluminescence, or other analyses of individual separates as well as determination of their relative proportions in the composite.

The past few decades have seen an increasing application of sophisticated techniques in the analysis of archaeological materials. Complex chemical and physical analyses have provided useful information concerning the ages of arti- facts and the sources of raw materials and the technologies involved in their manufacture. However, valid interpretation of the data produced by analyses of composite materials (most pottery, brick, mortar, and stone imple- ments) must involve knowledge of the relative contributions of the individual components. For example, the trace-element "signature" of a sherd of sand-tempered pottery will depend not only upon the clay(s) in the paste but also upon

the diverse minerals in the tempering material. It is conceivable that the trace-element content of a sherd may be largely determined by the chance presence (or absence) of a single grain of some minor component (such as zircon, monazite, or sphene) in the sand, resulting in different "signatures" for adjacent sherds from the same pot. Therefore detailed studies of heterogeneous substances may require separate analyses of each of the various components as well as a determination of their relative propor- tions and their distribution in the sample.

We report here a method for disaggregating relatively weakly bound composites (low-fired pottery, bricks, mortar, indurated soils, etc.)