If it is now assumed that HA is a very weak acid [(A-)
log [Fe]
- [HA] + (A-)
=
-
[HA]/(HA).
The reason I have arranged this expression in the above manner is simply because the quantities [Fe], [HA], and pH are essentially the experimental quantities reported by Shapiro. Thus this chelation model predicts a straight line relationship between log l/([Fe] - [HA]) and pH, with an intercept of log K. When the reported quantitative interaction data are plotted with this relation a perfect straight line results and a K value of approximately lo5 is obtained. There are of course many questionable assumptions involved in this model, but the result indicates the point I wish to make, namely that the existing data on color-iron interaction are not inconsistent with a chelation mechanism.
iron-color chelation [HA] = (A-)
- [HA]
+
Christman, R. F., and Ghassemi, M., "Chemical Nature of Organic Color
Table 1. Degradation products of natural organic color Rr, in solventa i
Absorption maxima, mp
3
EtOH
Compound
1
0-Dihydroxybenzene
0.96
0.41 I 0.55
203, 219, 279
262, 290
Ivf-Dihydroxybenzene
0.98
0.31
0.48
205, 223, 277, 283
245, 295
3-Methoxy-4-hydroxybenzaldehyde
0.89
0.59
0.68
210, 255, 320
250, 350
3-Methoxy-Chydroxybenzoic acid
0.26
0.10
0.57
259, 293
300
3,5-Dimethoxy-4hydroxybenzoic acid
0.03
0.03
0.51
213, 272
303
3,4-Dihydroxybenzoic acid
0.37
0.05
0.29
208, 252, 292
277, 302
3,5-Dihydroxybenzoic acid
0.20
0.00
0.24
a
4
Chemistry of the Oceans: Some Trace MetalOrganic Associations and Chemical Parameter Differences in Top O n e Meter of Surface
References
+ (HA)
2
in Water," J. Amer. Wafer Works 58 (6), 723 (1966). ASSOC., Shapiro, J., "Effect of Yellow Organic Acids on Iron and Other Metals in Water," J . Amer. Water Works ASSOC., 58 (8), 1062 (1964).
'
Solvent 1 : ethyl ether. Solvent 2 : benzene and ethanol (9O:lO) v./v. Solvent 3 : benzene, methanol, and acetic acid (95:8:4) v./v.
EtOH-NaOH
The impact of the present surge of interest in oceanography on chemistry of the oceans will doubtless be far reaching. In the past few years, chemistry has grown from a one- or two-man operation, mostly of analytical type, at each oceanographic institute or department to a group of fundamentally trained scientists attacking broad chemical problems of the oceans. As is usually the case, the recent advances have been preceded by new chemical concepts and techniques. The long-awaited utilization of instrumental methods for a much refined analysis of the major component relationships, such as salinity, have greatly enlarged our ability to detect minute differences in water properties. Perhaps the greatest advances, however, have occurred in the minor component and trace element areas. Development of such sensitive procedures as neutron activation analysis, radioactive detectors, isotopic dilution, polarography, mass spectrometry, gas chromatography, atomic absorption spectrometry, and thin layer, paper, and column chromatography has Volume 1, Number 4. April 1967 303
-
~
.
_
_
_
Distribution of chemical a n d physical forms of copper, manganese, and zinc shows wide variation in ocean watersa
0
0 500
500 n
$
-
1000
1000
c
1500
5P p"
1500
1
1/
W
1
2000
2000
s
I
2500
w
2
2500
5
1
3000
3000 3500
1.o
0.7
0
1.5 0
0.2 0.4
Copper (LLg./I.)
0.8
0.6
1.0 1.2 0
Manganese (pg./l.)
=Data t a k c n a t S t a t i o n 63A1-3 (25" 30";
Trace metal content ~~~
~
~~
Mostly Cu (substantial amounts), some Zn, negligible Mn Mostly Cu, occasional Zn, negligible Mn Mostly Zn (substantial amounts), some Cu, negligible Mn
Mn (almost all), substantial amounts of Cu and Zn
Table 2. Statistical analysis of dissolved organic carbon (D.O.C.) and nutrient concentrations in water collected from the surface and from 1 meter --
1 No. of paired Nutrient observationsn _ _ _ _ ~ _ _ ~ ~
1
D.O.C.
66
' ~
I--
Mean difference6
I
I
Calculat:;, '*Students s t
+o
44
3 62'
fO
080
3 67'
- -~ I
~
0
"4-
-
~
- 3P - N
71
I
~
I
60
l-
~
+O 311
I
4 39c
- - ~ _ _ _ _ _ _ ~ ~
NO,-
-N
-
68
'-+O
0084
2 42d
~~
s10, -
s 1 4
68
+O 723
Degrees of freedom, ti - 1 . Mean difference expressed in ,,g. A..'liter except for D.O.C. ~ h i c his mg.'liter Significant at the 0.1 7; level. ~1Significant at the 5 8 level.
n h c
Goering and Rienzel (1965).
304 Environmental Science and Technology
5.0
3500 6.0 7.0
93" 50'W) i n Sigsbee Deep, Gulf of Mexico (from Slowey, 1964)
(open ocean, Gulf of Mexico)
I
2.0 3.0 4.0
Zinc (pg./l.)
Table 1 . Cu, Mn, and Z n according t o physical size in the ocean
0.002p
1.0
1 19
provided means not only to estimate total quantities, but to resolve the dynamics of chemical cycling and contributing chemical forms in the system. Trace element chemistry, as recently elucidated, especially by neutron activation analysis and associated tecliniques, points to a complexity of chemical forms with elemental specificity. Many elements are found associated with particulate matter of various sizes while others of similar chemical properties may be found wholly in hz dissolved state. Recent data obtained by Slowey and Hood (1964) shown i n Table 1 demonstrate this point for Cu, Mn, and Zn. Arbitrarily, we chose 0.0111 and less to be in true solution and sizes greater than this to be particulate matter. The fraction 0 . 0 0 2 ~was obtained by ultrafiltration through viscose dialysis tubing. The portion retained, commonly called nondialyzable, is attributed to organic complexes firmly bound in the sea water. Other studies showed the divalent forms of the elements dissolved in sea water as assessed with Mn", CuG3, and Znfi5 radioisotopic tracers to be extractable with diethyldithiocarbamate and completely removed by dialysis. The nondialyzable portion upon oxidation with
persulfuric acid, a method used for analysis for the total element present, was extractable with this reagent. The distribution of all fractions of Mn, Cu, and Z n investigated, in a column of water in the Sigsbee Deep, is shown in Figure 1. This figure demonstrates the marked vertical variation in kinds and amounts of these trace metals in the ocean. L,kewise, horizontal variability, particularly in surface waters, is also great. The problem of types of organic compounds associated with the trace metals is almost untouched. Some data from iron exist and recently Slowey et a/. (1966) isolated a fraction of the Cu in some sea water samples with chloroform and showed it to be associated with phospholipid, porphorin, or aminolipid components. The organic chemistry of sea water has drawn considerable attention in very recent years. Methods of isolating dissolved organic material in sea water and of characterizing its rapidly proliferating constituents open up new ways of understanding biological and geochemical cycles in the sea and some important aspects of air-sea interactions. Sea surface chemistry with particular reference to the top 1 meter has resulted in some exciting observations. Goering and Menzel (1965) and Goering and Wallen (1966) showed highly significant differences in the concentration of dissolved organic carbon, HP04-, NH4+,and NOa- a t the surface and at 1-meter depth as shown in Table 2 . These data are the first to show chemical parameter anomalies near the very important sea-air interface, which may be important in mass transfer and heat and momentum exchange phenomena. Recent analysis of sea water for He, Ne, Ar, K r , and Xe by mass spectrometric techniques has revealed excess He over the noble gases in the deep ocean. This excess has been attributed to an influx of atoms of this gas from the lithosphere, where it is produced by natural radioactive decay of members of the uranium and thorium series. If steady state is assumed the rate of H e escape from the earth can be computed. Rare gases may also be used for studying the mixing of water masses in the deep ocean, since the concentration in sea water is determined by the equilibrium with the atmosphere when the water is at the surface.
Suggested additional reading
Goering, John J., and Menzel, David, Deep-sea Res., 12, 839-43 (1965). Goering, John J., and Wallen, David, Deep-sea Res., 13, 777 (1966). Slowey, J. F., Jeffrey, Lela M., and Hood, D. W., Annual Report to AEC from Texas A & M , Ref. 64-27A (1964).
The Analytical Chemistry of Water and Waste Waters
~
Chemical analysis for pollution control. The seriousness of the problem of water pollution and its impact o n environmental health are presently the focus of national attention. Never was there a time in the history of man when he was so deeply concerned with the quality of his water. The analytical chemist, as a member of a team combining various professionals such as scientists, engineers, lawyers, sociologists, physicians, and economists, plays a significant role in the total effort of water pollution control. His role requires him t o characterize the nature and magnitude of the problem, assist in executing a control measure or treatment process, and last but not least, provide continuous surveillance and monitoring of the final product-that is, clean water. To this effect the analytical chemist is the “eyes” and “ears” of any control measure, for without valid, meaningful analysis our efforts to control pollution will be fruitless, There was a time when all that water analysts did consisted of simple titrimetric and gravimetric procedures. Nowadays, with the obvious increase in
the magnitude and the ways in which man is polluting his waters, there is an ever broadening need for more accurate and precise information on water quality. The determination of a specific element o r compound in a water sample frequently requires extensive separation work to remove interfering constituents before identification and quantitative measurements can be performed. All too frequently, this is followed by one or multiple identification procedures which may involve the use of such sophisticated instruments as emission and absorption spectrometry, mass spectroscopy, NMR, x-ray, thermochemical, and electrochemical techniques. For example, the analysis for certain organic compounds in river waters requires, a t first, concentration by adsorption o n carbon columns, or partial freezing or reverse osmosis membrane techniques. This is followed by separation with liquid-liquid extraction, gas-liquid chromatography, or thinlayer chromatographic techniques and, finally, identification and measurement by infrared spectrophotometry. What is unique about water analysis? The chemical analysis of natural and waste waters is one of the most challenging tasks that is likely to confront any analytical chemist. The test solution is, in most cases, a complicated heterogeneous system that rarely lends itself to simple analytical techniques. “Water” analysis requires the subtle correlation of theory and experience of analytical principles, insight into the nature of interferences and other problems associated with the methodology, and the ability to properly interpret analytical results in correlation with pertinent field observations and the history of the water. Water pollution control can be looked a t as a specialized technology and, like any other industry, it has its own specific analytical needs. Analysis may be required to : Determine the compliance of certain waters or waste waters to quality standards for a n intended use, production control, o r disposal in a receiving stream. Estimate the possible detrimental effects of waste effluents o n the quality of a receiving water for subsequent downstream use. Evaluate treatment requirements in view of water reuse. Volume 1, Number 4, April 1967 305
