Tải bản đầy đủ - 0 (trang)
CHAPTER 8. CHEMICAL MONITORING OF SOILS FOR ENVIRONMENTAL QUALITY AND ANIMAL AND HUMAN HEALTH

CHAPTER 8. CHEMICAL MONITORING OF SOILS FOR ENVIRONMENTAL QUALITY AND ANIMAL AND HUMAN HEALTH

Tải bản đầy đủ - 0trang

306



DALE E. BAKER AND LEON CHESNIN



I.



Introduction



Agronomists serve the public through dedication to the goal of relieving

the harsh constraints that weight upon our stewards of the land. The farmer

looks to the agronomist for help in making decisions regarding soil management and crop production. Increased public concern for a quality environment exemplified in the United States by Federal Law, PL 92-500 with

its zero discharge goal, when coupled with an energy crisis, an increasing

rate of inflation, a monetary crisis, and a world food shortage, make it

mandatory that the agronomists be cognizant of their interface with related

disciplines in order to optimize production. The facts about pollution of

the environment in relation to animal and human health must be made

clear so that animal and human health as well as other aspects of environmental quality can be protected, while avoiding costly and unnecessary

constraints.

A systematic computerized search of the literature on the subject of soil

and water in relation to environmental quality produced more than 3000

titles and abstracts related to the subject since 1968, with perhaps 10%

being published in journals read regularly by those of us specializing in

soils and crops. The objectives of this review are ( 1 ) to consider aspects

of environmental quality in which soils may serve as sources or sinks for

potentially toxic substances in air, water, and the food chain, and ( 2 ) to

review and attempt to interpret methods and concepts important in soil

chemical monitoring.

“Science and the Quality of Life,” the theme of the 1975 annual meeting

of the American Association for the Advancement of Science (AAAS),

is one of many examples of the increased emphasis on the applications

of science and technology for the enhancement of man.

Land disposal of wastewater and sludge is receiving much publicity and

research support. Toflemire and Van Alstyne (1974) reported on six symposia including 139 papers with about 1000 published pages. More than

100 land disposal systems for wastewater were in operation in the United

States in 1972, and 14 new study areas were authorized by U.S. Environmental Protection Agency in 1973. Their 10-page review with 120 references provides convincing arguments for land disposal of wastes. They

noted that a May 1973 Gallup Poll “revealed that 40 percent of the people

would not object to drinking recycled sewage.”

The national emphasis on clean air and clean water using soils as “living

filters” requires that soil monitoring procedures include methods and implementation programs to protect crop plants and the food chain from attaining harmful concentrations of the various environmental pollutants.



CHEMICAL MONITORING OF SOILS



307



Compounds and metallic ions adsorbed or “fixed” by soils are less available

but not unavailable for absorption by soil organisms, plants, and ultimately

by animals and man. The degree to which water solubility reflects the biological availability of compounds and ions in soil changes with soil properties. Ultimately, the availability to plants, animals, and man of essential

and potentially toxic compounds and ions should be predictable from their

measured soil concentrations or solution activities as affected by soil properties, environment, soil organisms, plant species, and varieties, as well

as product processing methods.

The mineral composition of plants must be maintained at levels that

do not harm the health of man and animals. Bioinorganic chemistry of

animals is analogous to soil testing, plant analysis, and plant biochemistry

of inorganic elements and encompasses ranges in dietary concentrations,

elemental interactions and availabilities of ions that are deficient, optimum,

and toxic to man and animals. Before 1957, seven trace elements (Fe,

I, Cu, Mn, Zn, Co, and Mo) were considered to be essential for animals.

Since 1957, the elements Se, Cr, Sn, V, F, Si, and Ni have been added

to the list (Schwarz, 1974). Toxicology or the bioinorganic chemistry of

elements harmful to animals involves many of the essential elements as

well as nonessential trace elements. According to Schroeder ( 1974), elements of low natural abundance on the earth and in sea water are relatively

toxic to animals.

II. Soil Pollution Sources



A.



AGRICULTURAL

POLLUTANTS

A N D SOIL EROSION



“A Primer on Agricultural Pollution,” illustrated and summarized by

Wadleigh and Summers (1971), includes reviews by C. P. Gratts (Issues

in Environmental Quality) ; L. R. Webber (Animal Wastes) ; F. G. Viets,

Jr. (Fertilizers); J. P. Law and J. L. Sitherow (Irrigation Residues); R. L.

Metcalf (Pesticides) ; and A. R. Robinson (Sediment). The concepts and

data presented by the authors indicate the problems and their magnitudes and approaches for the wise use of land. Miner (1972) reviewed

the literature on agricultural wastes with respect to characteristics, application to cropland, gas and odor production, animal waste treatment techniques, and reuse of animal manures.

In “Agriculture and the Quality of Our Environment,” Brady (1967)

includes manuscripts on many aspects of agriculture in relation to pollution

of air, water, and soil. A recent bibliography with 1 1 5 selected references

on animal waste pollution and its control was prepared by Lehmahn

( 1974).



308



DALE E. BAKER AND LEON CHESNIN



Agricultural pollutants include plant nutrients, pesticides (herbicides,

insecticides, fungicides, etc. ) , animal wastes, and soil itself. Inadequate soil

conservation practices result in these pollutants finding their way into surface water prior to their degradation o r use by soil organisms and crop

plants (Willrich and Smith, 1970). Thus, in some cases, the soil becomes

sediment, the most prevalent pollutant of streams and lakes. Bondurant

( 1970) reported that studies by the Missouri Basin Inter-Agency Committee indicated that annually 6000-10,000 tons of soil per square mile per

year were lost from land in much of Woodbury, Monona, and Harrison

Counties in Iowa. In fact, annual losses up to 30 tons per acre were measured from small drainage areas. Adams et d.(1972) of the U.S. Department of Agriculture reported that the Mississippi River carries nearly 500

million tons of sediment to the Gulf annually. This much sediment would

replace the topsoil on nearly 500,000 acres per year.

Epstein and Struchtemeyer (1970) found that the concentrations and

amounts of endosulfan, endrin, and DDT were lower in runoff from land

in a rotation system of potatoes, sugar beets, and peas than from land

in continuous potatoes. Less than 1 % of the amounts applied were in

water, while the concentrations of insecticides were considerably higher

in the soil or sediment fraction. Insecticides were concentrated in the 0.08

to 0.5 pm clay fraction. Marshall soil retained more of each insecticide

than Caribou soil, probably because of the higher organic matter content

of Marshall soil. For the clay fractions, the Caribou soil retention of the

insecticides was greater than for the Marshall soil.

Hall, Pawlus, and Higgins ( 1972) and Hall (1974) demonstrated that

losses of atrazine in runoff water and soil sediment from field runoff plots

(14% slope) planted to corn ranged from 2.5% to 5.0% of that applied

at the recommended rate (2.2 kg/ha) for preemergent application to Pennsylvania soils. Losses of related chlorotriazine were similar, while losses

of a methoxytriazine from alfalfa totaled 0.02% and 0.03% at the 2.2

and 4.5 kg/ha rates, respectively. Losses of herbicides themselves were

of little consequence in all studies. However, runoff and soil erosion increased with the rates of herbicide application (Hall and Pawlus, 1973).

Plant nutrient applications amounted to about 15 million tons in 1967

(Adams et al., 1972) including 6 million tons of nitrogen, 4.3 of phosphate, and 3.6 of potash. The respective amounts increased to 17.8 million

tons in 1972-1973 including 8.3, 5.0, and 4.4 million tons for the respective macro elements (Tisdale and Nelson, 1975). Experiments at Missouri

have shown that where corn was grown continuously, 18 pounds of P per

acre was lost by erosion; for a crop rotation the loss of P was 6.2 pounds

per acre; and for a grass sod, only 0.1 pound per acre was lost each year.

Loss of nutrients through erosion leads to pollution of streams and lakes;



CHEMICAL MONITORING OF SOILS



309



and in light of the soil losses reported above, one could assume that, at

least to some degree, commercial fertilizer and lime are being substituted

for nutrient rich topsoil on cropland.

Soil erosion control becomes even more important now that concepts

of chemical monitoring of soils for environmental quality are developing

on the premise that potentially toxic trace metals and other soil pollutants

remain on the land. If the pollutants are eroded into streams and lakes

before they reach equilibrium with the soil, then the use of soil in waste

disposal has limited merit. Recent soil management innovations in sodseeding, minimum tillage, and zero tillage should be evaluated for erosion

control in addition to the economical production of crops.



B.



ANIMALWASTES



The quantity of municipal and industrial wastes produced in the United

States should be a function of population, suggesting that, with declining

birth rates, the problems associated with disposing of municipal and industrial wastes in soils might approach a maximum by 1990. On the other

hand, the quantity of animal and poultry wastes produced in the United

States appears to be a function of population and status of the economy.

In general, livestock numbers are influenced by market prices and tend

to follow cycles with periods of highs and lows.

A total of about two billion tons of manure are produced annually in

the United States (Loehr, 1968). While part of this waste is distributed

on pastures and rangeland, an enormous quantity is deposited in barnyards,

feedlots, and stockpiles. Taiganides (1967) states that farm wastes include

human wastes from America’s 13 million farm population, crop residues

of eight tons of plant wastes for each American family, wastes from rural

fruit and vegetable processing units and other rural industries, approximately 58 million dead birds per year, residues from agricultural chemicals,

and more than 50 billion cubic feet of animal wastes per year.

On the basis of population equivalence data (Taiganides and Hazen,

1966), the daily wastes from poultry, swine, and cattle are equivalent to

ten times the wastes of the human population of the United States.

The polluting constituents of manure that can adversely affect the environment include nitrate and other nitrogen compounds (nitrites, oxides of

nitrogen, and ammonium) ; trace elements (lead, arsenic, copper, zinc, sodium and potassium salts) ; disease organisms of man and animals; biodegradable organic substances; insects and vermin; weed seeds; and obnoxious odors.

Chesnin et al. (1975) pointed out that nuisances associated with the

animal industry include flies, dust, and odors. Flies and odors are more



310



DALE E. BAKER AND LEON CHESNIN



of a problem in warm, humid climates, whereas dust nuisances are restricted mainly to arid regions. Odors from manures originate from a variety of compounds, such as ammonia, organic acids, aliphatic amines, alcohols, ketones, aldehydes, and sulfur-containing compounds.

Elliott et al. (1970) found Co2, 02,N,, and CH, in the soil atmosphere

at depths ranging from 30 to 152 cm beneath a level feedlot and adjacent

cornfield. Hutchinson and Wets (1969) found that volatilization of NH,

from beef cattle feedlots contributed significant quantities of NH, to the

atmosphere. A lake in the vicinity of a large feedlot absorbed enough NH,

per year to raise its N content 0.6 mg/liter. Burnett (1969) found indole

and skatole among the components that contributed to the odor of chicken

manure. Aliphatic amines were found in incubated chicken manure (Burnett and Dondero, 1969), and amines were found in the atmosphere of

a swine confinement unit. Mosier et al. (1973) determined that aliphatic

amines were volatilized from a cattle feedlot.

Elliott et al. (1971 ) measured an increased volatilization of N compounds associated with feedlot disturbances, such as manure mounding.

One of the chief problems associated with concentrated high-density poultry operations is the control of the obnoxious odor emanating from manure

accumulations (Deibel, 1967). In the poultry house, some odor is disseminated into the immediate environment. However, the preponderance of

odor complaints are due to odors released during handling and disposal

of the accumulated manure-moving the manure from collecting pits in

the poultry house and spreading it on the land. Deibel (1967) found that

as poultry manure was stored, large quantities of steam-distillable fatty

acids were formed progressively.

Chesnin et al. (1975) pointed out that perhaps the most neglected factor

in the past use or disposal of animal wastes was an evaluation of the effects

associated with their chemical, physical, and biological properties. A voluminous literature exists on the effects of manure applications on crop yield

and composition. However, data on the chemical and biological characteristics of the applied manure are seldom reported. In the few instances

where such information is given, the data are fragmentary, rarely extending

beyond the nitrogen content or the N-P-K values.

In the chemical monitoring of soils treated with animal wastes, the various constituents in these wastes must be considered. The end product or

waste composition is quite variable, as it represents the influence of various

feeds and additives supplied to animals of different ages, physiological maturity, of different digestic processes, as well as the effects of waste decomposition, leaching, or volatilization losses, or mixing with soil or litter. Manure management systems and climate greatly influence composition.

The amount of manure produced daily by domestic animals varies con-



CHEMICAL MONITORING OF SOILS



31 1



siderably, as does the moisture content of these wastes (Table I ) . The

physical characteristics of animal size and daily manure production are

closely related. However, on the moisture free basis, Hart (1960) found

that the nitrogen content of poultry and sheep wastes was 5.4% whereas

the wastes of dairy, beef cattle, and swine contained similar amounts of

nitrogen, 3.5%, 3.1%, and 3.3%, respectively.

When the daily manure production figures of Table I were applied to

statistical data for Nebraska and Pennsylvania, some interesting comparisons were obtained (Table 11). The production of animal manure for 1971

was estimated at 64 million tons for Nebraska and 19 million tons for

Pennsylvania. If this manure were spread over the land planted to corn

in the respective states, the rates would be about 10 tons per acre for Nebraska and 12 tons per acre for Pennsylvania. If losses of N could be prevented, the manure would supply 70-100 pounds of N per acre, or about

half the amounts required for maximum corn yields.

The greater population in Pennsylvania, 11.9 million compared with 1.5

million for Nebraska, results in a much greater production in human manure for Pennsylvania (Table 11). For Nebraska the human manure is only

0.14% of the animal manure, and in Pennsylvania the human manure is

3.76% of the animal manure. Although these percentages reflect the

greater impact that sewage production could have on agriculture in PennTABLE I

Production and Characteristics o f Manure by Animals and ManaDetermination"

Grarns/day

Pounds/day

Moisture



(z)



Man



Cattle



Swine



Sheep Chicken Turkey



Duck



150 23,600



2700

5.94

67



1130

2.49



336

0.14

61



0.33



51.98

83



17



182

0.40

12



448

0.99

62



Cattle

Determination"



Dairy



Beef



Swine



Animal wt. (Ib)

Production (ft3/day)

Density (Ib/ftJ)

Moisture

Nitrogen

of dry wt.)



1400



950

1.0

60

85

3.1



200

0.28

62

82

3.3



(x)

(x



1.3

62

85

3.5



Geldreich (1966) wet weight basis.

Morrison (1951).

Hart (1960) fresh mixed manure and urine.



Sheep



Poultry



100



5

0.0062

60

12

5.4



0.11

65



11

5.4



312



DALE E. BAKER AND LEON CHESNIN



TABLE I1

Animal and Human Manure Production for Nebraska and Pennsylvania

Source of manure



Nebraska.

(tons/year, wet)



Pennsylvaniab

(tons/year, wet)



Cattle

Swine

Poultry

Sheep

Total animal manure

Human"



61,251,380

2,189,290

603,861

27,010

64,071,541

90,800



16,724,435

636,500

1,528,9O1

86,164

18,976,000

716,800



4



Calculated from Nebraska Agricultural Statistics Annual Report, June



1972.



Calculated from 1971 Crop and Livestock Annual Summary.

Based on population results from Statistical Abstracts of the United

States. 1974.



sylvania compared with Nebraska, it also becomes very evident that in

neither state is human manure a substantial source of N and other macronutrients required by field crops.

Manure collected by scraping bare soil areas in feedlots differs in content

from manure collected on concrete floors or in pits under confinement feeding buildings. Manure collected from the soil surface may contain up to

50% or more of soil, sand, stones, or gravel from the feedlot surface. In

determining the chemical composition of feedlot wastes, it is important

to determine the extent of contamination of the waste with inert solids.

Whereas sand is a common part of feedlot manure in the desert southwest,

or the plains of eastern Colorado and western Kansas and Nebraska, silt

and clay are common constituents of manure in the feedlots of eastern

Nebraska and western Iowa.

Unfortunately many studies involving animal wastes give no measure

of possible adulteration of the waste with other materials. Since the moisture content of manure varies greatly from one climatic region to another

and is influenced by management practices and local weather phenomena,

data concerning the application or composition of animal wastes should

be based on an oven-dry or dry solids basis.

Some chemical properties of manure recorded by Meek et al. (1975)

at Brawley, California, are presented in Table 111. Feedlot manures of the

desert Southwest are reported to be high in ash, low in organic carbon,

and high in soluble ions or salts.

The guidelines for manure utilization (Chesnin et al., 1975) recommended by the Western Regional Committee, W-124, and a publication



CHEMICAL MONITORING OF SOILS



313



TABLE 111

Representative Composition of Beef Cattle

Feedlot Manure from the Arid Southwest.

~



Constituent



Composition

(oven-dry basis)

63.7

10.0

1.98



3.5

1880

2.80



1.12

I .53

2.84



0.27

0.52

0.48



30

9

I53

99

137

~~



(I



~



Meck et a/. (1975).



prepared by ARS-USDA (1974) are excellent. In the final analysis, maintaining environmental quality when using animal wastes requires chemical

monitoring of wastes, soil, and plants, along with the necessary follow-up

action to prevent pollution.



c.



INDUSTRIAL AND



MUNICIPAL

WASTES



Industrial wastes as pollutants of air or irrigation water and municipal

wastes in the form of sewage sludge or solid waste have some hazardous

properties in common with agricultural wastes. Toxic metal buildup in soil

may occur from manure disposal (Baker, 1974; Davis, 1974) and from

the use of pesticides (Wiersma et al., 1971; Yobs, 1971; Deubert and

Denoranville, 1970). For agricultural and food processing waste disposal

on land, it is possible to estimate pollutants requiring monitoring because

their sources are known. For example, if swine or poultry are fed high

levels of Cu and Zn, then these elements as well as other macro plant

nutrients should be monitored on fields treated with manure. On the other

hand, for industrial and municipal wastes, the source of potentially toxic

substances are not known. A partial listing of the elements, compounds,



314



DALE E. BAKER AND LEON CHESNIN



and other pollutants that could be present in toxic amounts for plant, animals, and human beings includes: Cd, Zn, Cu, Ni, As, Hg, Pb, B, se,

Mo, V, Cr, Be, Bi, polychlorinated biphenyls (PCBs) , pesticides, acids,

detergents, oil, cyanide, soluble salts, and pathogenic organisms.

Multiple pesticide residue monitoring techniques and procedures have

been developed by the Division of Chemistry and Toxicology, Bureau of

Foods and Pesticides, FDA, HEW. A detailed description of extraction,

clean-up, gas chromatographic, and thin-layer chromatographic procedures

are included in the 11th edition of “Official Methods of Analysis” of the

AOAC. Development of the procedures have been reviewed by Burke

(1971 ). More recently, Bosley (1974) described computer-assisted automated drug analysis. Similar methods of monitoring for soil pollutants will

be required to allow land application of municipal sewage sludge and other

solid wastes without harmful effects. Soil enrichment with several trace

elements would be many times greater from land applications of sewage

sludge than from plant residues (Table IV) . Existing fertilizer regulations

would need modifications to limit the levels of potentially toxic substances.

This approach was recommended by Chumbley ( 1971 ) and has been discussed by Chaney ( 1973, 1975 ) . Personal communication with Chaney

indicates that national guidelines are being proposed to regulate the use

of sludges on land on the basis of their Zn equivalent concentrations of

Cu, Ni, and Zn and Zn:Cd ratio. The guidelines are considered in an ARSUSDA (1974) publication. A program is in operation in Pennsylvania

(Franz, 1974), where farmers are being advised not to use sewage sludge

on cropland of medium soil texture if the sludge contains excessive concentrations of trace elements. Recommendations for maximum levels of

trace elements developed independently by Baker and by Chaney, are presented in Table V. Interpretations of geochemistry data and soil-plant relations over time for different soils account for the different proposed limits.

If waste materials applied to land are carefully monitored and regulated,

then chemical monitoring of soils and plants can be used to prevent the

buildup in soils and crops of essential plant nutrients and potentially toxic

metals. Municipal sewage sludge contains the contaminants removed from

waste water by physical, biological, and chemical treatment. Action by industries to prevent the accumulation in sewage of PCBs, metals, and other

substances toxic to plants will not eliminate the need for monitoring the

levels of Cu, Cd, Zn, and Pb in sewage sludge (Dean and Smith, 1973).

Sources of Cu and Zn in sewage sludge are thought to be brass plumbing

fixtures and soft water dissolution of copper and galvanized metals in domestic plumbing. The sources of Pb have not been isolated, but storm water

carrying the residue from automobile exhausts are suspects. Thus, sewage

sludge produced in accordance with the most advanced technology and



CHEMICAL MONITORING OF SOILS



315



TABLE IV

Nornal Range and Suggested Maximum Concentration Values for Plants"; Range and

Median Values for Sewage Sludge from 300 Treatment Plants in the United States, Canada,

Sweden, England, and Walesh; Range of Means for 6 Treatment Plant Sludges in

Pennsylvania Sampled Biweekly for 6 Months"; and Range for 12 Sewage

Sludges Where Digestor Failures Occurredff

~~



Concentrations of metals (ppm, dry wt.)

Plant leaves



Fe

Mn

Zn

cu

Mo

B

Cr

Se



co

I

F

Ni

Pb

Li

Cd

Ag



As

Ba

Hg

Sn

V

(I



Ir



Sewage sludge



Range"



Maxiz



Rang&



Medianh



Rangec



Ranged



20-300

15-1 50

15-1 50

3-40

0.2-1 .o

7-75



750

300

300

I 50

3

1 50

2

3

5

I

10

3



-



-



-



60-3900

72-49000

52-1 1700

2-1000

6-1000

20-41000



500

2000

500

5

50

200

I



-



-



1053-6540

872-1 718



1300-2 1 200

360-10300



143-1498



200-9100

-



0.1-0.5



0.05-2.0

0.01 -0.30

0.1-0.5

1-5

0.1-1.0



0.1-5.0

0.2-1 .o

0.05-0.20



10

5



3



-



-



0.01-1 .o

10-100

0.001-0.01



2

200

0.04



-



0.1-1.0



-



2



-



2-260

-



10-5300

1 5-26000

1 -I 500

5-1 50

1-18

150-4OOo

0.1-56

40-700

20 -400



10



-



50

500



10

10

5

1000

5

100

50



-



-



-



-



41 -429

239-3407



<50-2000



1 3-298



<50-2850



-



-



220-3500



-



-



-



Melsted (1 973).

Page ( I 974).

Baker and Hornick (1974).

Regan and Peters (1972).



under guidelines of PL 92-500 will likely contain the nutrient elements

N, P, K, Ca, Mg, Na, S, Mn, Fe, Cu, Zn, and B. In addition, the common

amounts of Cr, Se, and Mo present in biological wastes could have important beneficial effects on the food chain, while the presence of Cd, Hg,

Ni, Pb, PCBs, pathogenic organisms, and possibly Sb, Be, As, V, and Ge

must be prevented from reaching hazardous levels within the food chain.

The quantity of these elements and substances added to soils can be more

easily determined by analyzing the sludge before application than by trying



316



DALE E. BAKER AND LEON CHESNIN



TABLE V

Maximum Trace Element Concentrations Recommended

for Municipal Sewage Sludges Applied to Cropland

Bakera

(ppm, dry wt.)



Chaneyb

(ppm, dry wt.)



Zn

cu

Ni

Cd

Cd

Pb

Cr



1 500

7 50

1 50

50



2000

1000

200

15

1.0% of Zn

lo00

lo00



Hg



-



Element



a



b



-



550

500



10



Franz (1 974).

ARS-USDA ( I 974).



to measure their potentially toxic levels through soil analysis after

application.

Ill.



Soil and Waste Composition Monitoring



Pollutants in the environment should be defined, monitored, and regulated on the basis of the following characteristics: ( 1 ) production and consumption within an area; ( 2 ) mode of transport into the environment; ( 3 )

persistence in a potentially hazardous form within the environment; (4)

toxicity or accumulation of poisonous concentrations by plants, animals,

and human’beings; ( 5 ) teratogenic effects of long-term exposure by animals and man to low concentrations; ( 6 ) aesthetic considerations, such

as eutrophication.

The relative importance of each item above and acceptable levels of

contamination differ for each potentially hazardous substance. Phosphate

receives consideration primarily under eutrophication. DDT was banned

from use because of persistence and toxicity; nitrate-nitrogen is a problem

because of item 1, 2, and 4, and cadmium is receiving attention because

of items 1-3 and 5 . Thus, chemical monitoring procedures for soils and

wastes applied to soils cannot be easily formulated. Graham-Bryce ( 1972)

referred to pollution as “an imprecise concept that is difficult to define

satisfactorily.” With respect to agricultural chemicals, to be classified as

nonpollutants they should not persist in biologically active forms for longer

than is necessary for their intended effects and they should be free from

undesirable side effects. If we define agricultural chemicals to include all



Tài liệu bạn tìm kiếm đã sẵn sàng tải về

CHAPTER 8. CHEMICAL MONITORING OF SOILS FOR ENVIRONMENTAL QUALITY AND ANIMAL AND HUMAN HEALTH

Tải bản đầy đủ ngay(0 tr)

×