Raritan Bay Paper - Polluted Estuary

8/8/2019 Raritan Bay Paper - Polluted Estuary

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ENVIRONMENTAL CHARACTERISTICS OF RARITAN BAY,A POLLUTED ESTUARY

Harry P. JeffriesNarragansett Marine Laboratory, University of Rhode Island, Kingston, Hhotlc~ Ih~dABSTRACT

Temperature, salinity, dissolved 02, PO,-P, and NO:,-N in Raritan Hay, N. J. vvere detcr-mined over a 16-month period. Each reflects the circulation pattern in which sea waterfloods along the northern shore, enters a region of mixing with river dixhargc in the head ofthe bay, and then ebbs out along the southern shore.At the mouth of the bay, salinity was higher on the northern than on the southern side.The mean annual monthly difference at the surface was 1.272,; departures from the meanwere related to river flow.Surface and bottom dissolved O2 content were minimal in August arid Ilighcxt duringwinter. Low concentrations occurred in the Raritan River, especially. during the summerpreceding operation of a trunk sewer.The primary source of NOJ-N was outflow from the Raritan River. Prior to operation ofa trunk sewer, the river may have discharged significant quantities of PO,-1 into the bay.Throughout spring and summer, PO, concentrations rose and NO:{ decreased. It is pohtu-lated that the resultant low N:P ratio was partially due to an efficient nutrient regenerationmechanism that favored the rate of P renewal.A combination of rich nutrient supplies arising from natural and domestic soruces, plrls asluggish circulation, efficient nutrient regeneration mechanism, and scarcity of nnrcroscopicalgae combine to form an estuarine environment capable of supporting estrernely dcbnscpl&kton populations.INTRODUCTION

The Raritan is one of a system of bays andlagoons characterizing the Atlantic Coast ofNew Jersey. Such waters, affording readyaccess by ocean-going vessels to industrial-ized areas, have become an important factorin the economy of the state. Valuable bio-logical populations dwelling within thesebrackish waters and recreational opportuni-ties provide a variety of occupations. Insome areas, including Raritan River and Bay,biological and aesthetic values have sufferedgreatly from industrialization. Prior toWorld War I, the bay supported profitableoyster crops and diverse fish stocks. Today,with the surge of urban growth and industri-alization, pollution has brought the demiseof the oyster industry, greatly reduced abun-dances of fishes, and all but eliminated recre-ational aspects. A multimillion dollar trunksewer, which began operation in the RaritanValley in January, 1958, gives primary treat-

l Contribution No. 35 from the Narragansett h4a-rine Laboratory. This investigation was supportedby Office of Naval Research contract NR 083-054and by Public Health Service grants RG-7003 andRG-5278.

ment followed by transportation of sludgeto offshore disposal areas and discharge ofliquid effluents into the head of the bay.The Raritan system ( Fig. 1)) approxi-mately 25 miles in length, is oriented in ageneral east-west direction. It is divisibleinto three parts progressing seaward: Rari-tan River, Raritan Bay, and Lower New YorkBay. Depths are relatively shallow, increas-ing gradually from either shore to 22 ft inRaritan Bay and 28 ft in Lower Bay.Raritan Bay has the triangular shape of aflattened funnel; morphometrically, it typi-fies an ideal estuary. Source waters-freshfrom the Raritan River and salt from LowerBay-enter the basin at opposite ends witha tendency for each to flow to its respectiveright side. Mixing produces a great counter-clockwise gyre of slowly circulating watermasses. The net currents of this gyre, illus-trated schematically in Figure 2, establisha series of physical-chemical gradientsdirected along, and at right angles to, theaxis of the estuary. This investigation wasundertaken to: 1) relate distribution of phys-ical and chemical factors to pattern of circu-lation, 2) evaluate alterations of estuarine

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22 HARRY P. JEFFRIES

NEW JERSEY 40025

FIG. 1. The Raritan system, showing locations of scvcn routine collection stations; dotted line indi-cates 20-ft contour.nutrient cycles by pollutants, and 3) deter-mint basic conditions of the environmentfor testing the thesis that estuarine planktoncommunities create an array of phenomenawhich reflect physical-chemical gradients.Plankton studies will be presented in subse-quent reports.

Previous Studies on Circulationof the RaritanFigure 2 was prepared from the findingsof Ketchum ( 1950), M,armer ( 1935)) Ayers,

Ketchum, and Redfield ( 1949), Rudolfsand Fletcher ( 1951)) and Udell ( 1951).These intensive, short-term investigationsdemonstrated that the flushing of Raritanand Lower Bays was dependent primarily onthe resultant of localized inequalities induration and strength of ebb and flood tides.In relation to volume of the embayment,little water escapes with each cycle. Meantidal range was 5.5 ft, and the surface area ofthe Raritan system surveyed by Ketchum(1951a) was 1,670 X lo6 ft2. IIence, totalvolume of the tidal prism was 9,200 x 10fi ft3,or 300 times more water than was introducedby the river during a tidal cycle in Decem-

ber, 1948. Flushing times calculated byKetchum (1951b) for Raritan Bay rangedfrom 32 to 42 tides for maximum and mini-mum river flows. Sixty tides were requiredto flush river water through the entire estu-ary during the December, 1948 survey.Salinity in Lower Bay was 25-26%, at thetime of Ayers survey. The component flood-ing into Raritan Bay approaches its northernshore, continues past station 4 (Fig. 1 ), andarrives in an area of extensive eddies and

FJG. 2. Schematic representation of net currentsin Raritan and Lower Bays.


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HYDROGRAPHY OF A POLLUTED ESTUARY 23mixing with fresh water near the confluenceof the Raritan River and Arthur Kill. Thelatter is not a significant source of freshwater but rather a surge basin contributingto mixing processes. A southward thrust offlooding water reaching station 3 nearlybisects the protrusion of Raritan River dis-charge resulting from the previous ebb tide.According to Ayers, this appears to exert amilking action which accelerates the sea-ward movement of freshened water alongthe south shore of Raritan Bay at the sametime damming back the water accumulatedin the head of the bay.

METHODSField Operations

Six principal stations were established inRaritan Bay ( Fig. 1). They were visitedweekly during the summer of 1957 andbiweekly thereafter until September, 1958.A seventh station situated between 5 and 6was not sampled routinely. An eighth sta-tion between 5 and 7 provided additionalphysical and chemical data. Several collcc-tion points in the Raritan River and LowerBay supplemented the routine program. Onprincipal stations, water temperature wasmeasured with a reversing thermometer,conditions of weather, wind, and wavesrecorded, and water samples taken with aFoerst bottle for subsequent determinationsof salinity, dissolved oxygen, nitrate-nitro-gen, and phosphate-phosphorus.

Laboratory OperationsSalinity was measured according to themethod of Knudsen modified for use with a25-ml burette.Inorganic phosphate-phosphorus was de-termined by the Deniges-Atkins method asdescribed by Wattenberg (1937). Stocksolutions of stannous chloride specified byseveral authors produced erratic values onstandard phosphate solutions. Reproducibleresults were obtained at high phosphate con-centrations with a freshly prepared reagent

consisting of 125 mg stannous chloride in 25ml 1: 10 v/v HCL. Optical density was meas-ured in a Lumertron colorimcter with a 660-rnp filter. Apparent phosphate was corrected

for salt interference using unpublishedstandard curves provided by Dr Harold H.Haskin.Nitrates were determined by the methodof Mullin and Riley ( 1955)) giving particu-lar attention to buffer pH. Attempts toderive reliable salt correction factors usingbay water depleted of nitrate with Skeleto-nema costatum were unsuccessful, perhapsdue to inhibition by variable concentrationsof organic matter. A correction factor foreach sample was derived by making tripli-cate determinations. One flask was treatedin the routine manner, and 10 ,ug nitrate-nitrogen were added to sample portions ineach of the other flasks. The slope obtainedfor optical density versus nitrate for thesedeterminations was compared with stand-ards prepared in distilled water, and a cor-rection factor calculated.Prior to each run of dissolved oxygensamples, N/40 sodium thiosulfate was stand-ardized against potassium biniodate undersubdued light.

REXJLTSRegional comparisons are facilitated by

considering stations 1, 5, and 6 which formthe apices of a triangle encompassing Rari-tan Bay. Collectively, these stations monitorthe entrance and exit of source waters andwill be referred to as the triangle stations.Data are summarized in Table 1 for eachseason during the course of the investigationusing arithmetic means and their 95% confi-dence intervals.Temperature and Salinity

Regional tcmperaturcs reflected circula-tion patterns with greatest clarity duringspring, when a pronounced lag in the rateof vernal warming developed on the north-ern side of the bay. From mid-April throughJune, station 6 was 1.7 to 3.5C cooler than 5at the surface. These variations are attrib-uted to flood tides carrying cool high salinitywater through the northern portion of thebay. This water warmed less rapidly in thedepths of Lower Bay than Raritan River dis-charge which flows along the axis of theodd-numbered stations extending down thesouthern shore.Size of the confidence intervals for sur-


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24 HARRY P. JEFFRLESTABLE 1. 95% confidence intervals for true mean temperature (C), salinity (go), dissolved oxygen (ppm),inorganic phosphnte-pl2osphorus (pg-at/L), and inorganic nitrate-nitrogen (pg-at/L) at stations 1, 5, and 6.Summer, 1957-summer, 1958-~ -_ ~ - -~. - -~~__TEMPERATURESurface stations Bottom stations--~_--1 : 6 1 5 6Summer 24.3 + 0.9 23.0 1.0 23.2 -t- 0.9 23.7 k 0.7 22.1 -I- 0.7Fall 21.7 + 0.811.7 Ik 4.5 9.7 2 4.3 11.1 4.2 11.9 2 4.0 10.0 IL 4.1 12.1 -c- 5.2Winter 3.4 k 2.9 2.9 2 1.6 2.4 1.8 3.0 zk 2.0 3.4 f 1.8 2.3 + 1.5Spring 14.1 I!I 6.0 13.6 k 5.5 12.0 & 4.5 13.4 zk 5.3 12.4 & 5.1 11.6 2 4.9Summer 24.0 k 2.8 23.2 k 3.0 22.8 I+ 2.9 23.6 & 1.2 22.3 -+ 2.6 21.6 X!I 2.5

SALINITYSurface stations Bottom stations1 5 6Summer 24.02 -I- 1.14 26.37 2 0.46 26.91 -c- 0.60 24.26 : 1.12 26.59 : 0.54 :7 10 0 41Fall 21.77 2 2.24 26.12 zk 1.20 27.14 2 0.71 22.71 2 2.45 26.35 -I- 1.22 27:28 + 0:82Winter 12.88 -I- 6.86 19.55 k 1.38 23.27 iz 2.17 18.93 +- 4.42 21.46 zk 3.14 22.75 k 3.26Spring 11.82 k 6.91 17.98 zk 4.47 19.13 -L 6.41 16.50 + 4.07 19.80 zk 4.36 2mO.69 I- 4.56Summer 25.09 & 2.22 26.23 -c 1.42 26.74 k 0.82 24.95 k 1.32 26.59 & 1.72 27.39 -c- 0.80

DISSOLVED OXYGENSurface stations Bottom stations__-SummerFallWinterSpringSummer

SmnmerFallWinterSpringSummer

4.17 : 0.89 8.76 :11.44 7.84 : 1.85 3.73 2 7.13 : 60.81 1.22 6.24 0.804.32 2 1.33 8.68 -t- 2.38 8.03 ?I 1.17 4.57 -I- 2.02 8.41 & 1.78 7.87 1.179.12 2 1.14 9.94 -t- 0.32 9.89 -t- 0.67 9.03 AZ 1.15 9.74 2 0.51 9.60 IL 0.446.18 IL 2.08 7.64 5 1.57 8.31 IL 3.01 5.56 + 2.56 7.30 k 2.85 7.93 Ik 3.144.80 + 0.45 6.86 _+ 2.98 8.07 5 3.85 3.77 k 1.44 5.65 -c- 1.60 5.83 in 1.65

INORGANIC PO4-PSurface stations Bottom stations1 6 62.76 -t- 0.76 2.20 : 0.78 4.29 Ik 2.00 3.82 : 1.30 2.93 : 0.85 4.16 f 1.523.67 -t- 1.85 3.55 + 0.33 4.33 2 0.79 4.37 + 0.45 3.65 k 0.26 4.34 k 0.552.05 + 1.15 2.69 k 1.73 1.99 I!z 0.45 - - -1.79 c 1.01 1.78 + 0.76 3.25 I+ 2.59 - - -3.05 k 1.38 2.58 zk 2.14 3.38 + 1.70 - 3.53 + 1.81 4.81 k 0.46

INORGANIC NO+NSurface stations1 5 6Winter,Spring 95.9 zk 41.7 34.7 zk 13.6 26.3 & 11.6Summer 27.9 * 16.0 13.6 + 9.4 6.7 + 9.7

a mean -C standard deviation, N = 2.b 1958 only.face salinity in Table 1 indicates spatial dif-ferences in mixing of ebb and flood tidalcurrents and seasonal variation in river flowrates (Table 2). These intervals are maximalat station 1, denoting mixing of fresh andsalt waters in the head of the bay, and mini-mal during the summer ( 1957 in particular)when river flows were low and relativelyconstant.

Differences between mean monthly salini-ties at stations 5 and 6 provide a series ofindices which are related to variations in thedynamics of flushing. A positive value in

Figure 3 expresses the extent to whichstation 6 was more saline than 5 in partsper thousand. Control lines establishingconfidence limits for the difference bctwcenannual means at the two stations were calcu-lated by pairing monthly data according tothe method given by Dixon and Massey( 1957, p. 128). Positive values less than1.27%0, he mean annual difference, occurredfrom June through December, 1957, andthen increased abruptly, attaining a peak inFebruary. This relationship indicates theextent of bilateral separation of ebb and


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HYDROGIIAPIIY OF h POLLUTED ESTUARY 25________-____----___--__----;iljxd_ _1957 1958FIG. 3. Differences between monthly mean sa-linitics at stations 5 and 6. The relationship is posi-tivc when station 6 is more saline than 5. Annualmean diffcrencc and 95% confidence interval fordiffcrcncc between paired means are indicated.

flood water masses. Extremely low riverflow during the summer was apparently wellmixed with bay water before ebbing muchbeyond the mouth of the river. In thislocality, surface and bottom salinities gen-erally differed by less than lso from Junethrough November, 1957. Pronounced bilat-eral ialinity differences from January toMarch were associated with river dischargeincreasing 6 to 50 times over summer Gdautumn rates. The precipitous decline froma bilateral difference exceeding the uppercontrol limit in March to a reversal of theusual relationship in April may have beendue to Hudson River flow, augmented byspring thaws in its upper drainage basin.This helped to produce a dilute source seawater for Raritan Bay, By the distributionof coliform bacteria, Udell ( 1951) demon-strated a tongue of water extending fromThe Narrows toward station 6 during sum-mer. The full force of fresh water from theHudson River system may have arrived herein April and expanded the usually limitedflow into the bay.

trations in the head of the bay and progres-sive increases in oxygen content along thesouthern shore as river water became furtherdiluted with bay water (Table 3). A trunksewer serving the Raritan Valley beganoperation in January, 1958. Immediatelythereafter, oxygenation improved rapidly atstation 1 and in the river. Higher surfacethan bottom values in Table I are doubtlessassociated with phytoplankton photosynthe-sis in surface strata overriding oxygen con-suming processes of organic decompositionand respiration by benthic animals (Patten1961) . Inorganic Nitrate-Nitrogen

Dissolved Oxygen

In the mouth of the Raritan River, concen-trations cxcecding 100 pug-at/L occurred dur-ing the spring of 1958 and were higher forthe most part than at bay stations during theremainder of the investigation. Several sam-ples taken within the river gave still higherreadings and ranged from 106 to 194 pug-at/Lindicating that the river is an importantsource for plant nutrient and must play a sig-

Dissolved oxygen concentrations rosefrom minima in August, 1957 (less than 2.5ppm at station 1) to values near saturationfor the bay in general during the followingwinter and spring. Throughout the first halfof the field program, the Raritan River wasextremely polluted; in August no oxygencould be detected in surface and bottomsamples taken 3.8 and 7.4 miles upstreamfrom the rivers mouth. This condition wasreflected by relatively low oxygen conccn-

TABLE 2. Mean daily clischarge rate of RaritanRiver in ft3/sec, 1957-l 958-~

Month 1957 1958January 925 2,739February 1,754 1,854March 1,578 3,716April 3,022 3,246May 648 2,359June 280 557July 131 709August 95 360September 122 346October 148 -November 283 -December 2,393 -

TABLE 3. Metm concentration of oxygen (ppm) atsurface stations along the New Jersey shore. Alter-nate months, August, 1957 to July, 1958StationMonth 1 2 3 5

August 3.71 4.38 5.71 9.90October 4.59 6.10 7.33 9.t-m-.--anuary and February 8.66 8.55 9.34 10.06March 9.43 9.26 9.17 9.86May 5.90 5.08 5.20 7.03July 4.90 6.70 5.39 6.69


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26 HARRY P. JEFFRIES

FIG. 4. Surface inorganic phosphate-phosphorusand nitrate to phosphate ratio (bar graphs) at sta-tions 1,5, and 6.

nificant role in the primary productivity ofRaritan Bay.The pattern was a gradient of consecu-tively lower concentrations extending downthe river and along the southern shore.In mid-summer, when river flow and theamount of nitrate discharged into the baywere minimal, station differences were less;however, they maintained the same generalrelationship. The trunk sewer is evidentlynot the most important source of nitratesince relatively low values, often intermedi-ate between those at stations 1 and 3, wereobtained at 2, located 400 yards southeast ofthe sewer outfall. According to Dr MyronRand, Chief Chemist of the MiddlesexCounty Sewage Authority, domestic sewagecontains about 1 ppm of nitrate-nitrogen.This is the same order of magnitude as Rari-tan River water. Even though the volumeof effluent from the sewer is considerable,distribution of phosphate, discussed below,in the vicinity of the outfall indicates rapiddilution of discharged waste materials. Inmost instances, nitrate was minimal at sta-tion 6 indicating lesser contributions fromthe sea than from the river.

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2

t I I I I I I I I-I2 4 6 8MILES FROM RIVER MOUTH

FIG. 5. Spatial distribution of surface phosphate-phosphorus in the Raritan River before (brokenline ) and after ( solid lines ) operation of the trunksewer.

Inorganic Phosphate-PhosphorusA general non-parametric distribution forphosphate which reflects the course of tidalcurrents can be described for Raritan Bay.

The following pattern, showing rank orderof surface phosphate concentration at thevarious stations, was obtained for the periodof sampling with the sign test. Values weremaximal at station 6 in most instances andsmallest at station 5, directly across the bay.6>4>(1=2=3)>5

Noting relationships at the triangle sta-tions ( 1, 5, and 6) and in the Raritan River( Figs. 4 and 5), it is apparent that there aretwo major phosphate sources. The first andperhaps more important is Lower Bay waterflooding into Raritan Bay along the northernshore. On all but 4 cruises, concentrationswere higher in this area than directly acrossthe bay at station 5. Influx of phosphate,perhaps by an incursion of Hudson Riverdrainage, is suggested by dilution of thetongue upon progressing into the bay.Contributions of phosphate originatingfrom discharged sewage and land runoff arenot distinct in the head of the bay sincevalues varied mndomly in this intensive mix-ing zone. Previous to operation of the trunksewer, phosphate content increased pro-


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HYDROGRAPHY OF A POLLUTED ESTUARY 27gressively going upriver and exceeded 7.7pg-at/L upon reaching fresh water 8.6 milesfrom the mouth (Fig. 5). Waste materialsthen discharged into the river may havebeen responsible for the upstream gradient.Following initiation of trunk sewer opera-tion in January, 1958, concentrations in theriver were lower, for the most part, than inthe bay. Rapid mixing of sewer effluent andbay water was demonstrated by phosphateconcentrations in the immediate vicinity ofthe outfall. Surface samples taken on an ebbtide 100 yards to the east and west of the out-fall showed a threefold difference in con-centration: 2.90 pug-at/L on the river sideand 9.35 pg-at/L immediately downstreamfrom the discharge point, but 400 yardssoutheast at station 2, the content was 2.83pg-at/L.

DWXJSSIONSpatial distribution of the physical andchemical properties reported here exhibitgradients directed along and at right anglesto the axis of the estuary. Degree of devel-opment depends upon season and specific

property considcrcd. Variations in regionaltemperature and salinity relationships aredue to amount of fresh water inflow, differ-ent heat budgets in source areas of freshand salt waters, and changes in the salinityof source sea water. During wet seasons,partially mixed river discharge flows overmore saline bottom water with increasedrapidity and is deflected toward the south-ern shore as the flushing mechanism adjuststo an increased fresh-water load. Gravita-tional forces tend to spread the less densemixture across the surface of the bay (Ayers,et nl. 1949), but when runoff is high, alarger proportion of river water probablyebbs along the southern shore than in dryperiods. Biological populations dwelling inthe head of the bay or any material intro-duced into this area will be transported outof the estuary faster than expected by theproportionate increase in river dischargeover periods of low flow rates.

Gradients exhibited by non-conservativeproperties-dissolved oxygen and nutrients-also reflect circulation processes. Regionalvariations in concentration are determined

not only by physical mixing processes but, inaddition, are coordinated with seasonal rates of biological activity. The ebb circulationdirected along the southern shore is enrichedwith nitrate emanating from the RaritanRiver, Nitrate concentrations at station 5,in the path of the ebb flow at the mouth ofRaritan Bay, averaged 1.5 times higher than2.8 miles directly north across the bay atstation 6, located on the axis of the floodcurrent. Phosphate is supplied to RaritanBay at its landward and seaward extremesin the fresh and salt waters entering theb ay. Consequently, regional differences areless marked than those for nitrate. Whenphosphate concentrations at 6 stations arearranged in a decreasing rank order, therelationship (station 6 > 4 > ( 1 = 2 = 3) >5) indicates that phosphate is maintained inRaritan Bay in the following manner: 1)Waters high in phosphate enter the bay withthe net landward tidal flow along the north-ern shore. 2) Absorption by phytoplanktonreduces the concentration progressing intothe head of the bay, where contributionsfrom the river and trunk sewer are thenrcceivcd. 3) Utilization continues in the netebb current directed along the southernshore with the result that water leaving thebay is rclativcly low in phosphate. This phos-phate conservative intake-discharge mech-anism is probably associated with extremelyhigh chlorophyll levels during summer ( Pat-ten 1959) and bears a resemblance to theprocess dcscribcd by Hulbert ( 1956b) forFalmouth Great Pond.A pronounced spring maximum similar tothat obtained for nitrate did not occur. Sincewe must assume that land runoff during wetspring months contains quantities of phos-phatc in addition to nitrate, there may be aselective mechanism of phosphate removalespecially operative at this time. Turbidityis very high during spring; indeed, visibleevidence of the ebb current along the south-ern shore was shown on 1 March by a dis-tinct band of muddy water leading from theriver across station 5. In the river itself, sus-pended material became so dense that acoarse plankton net was completely cloggedand the attached bucket filled with tracheo-phyte detritus. Phosphate adsorbs onto col-


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28 HARRY P. JEFFRIESloidal micelles and other suspended material,and with settling, the nutrient is probablyremoved from biological circulation in Rari-tan waters until summer when detritusfeeders become active. Carritt and Goodgal( 1954) suggested that dissolved substancesare removed in the turbid headwaters of anestuary and then released following trans-port into the area where fresh and salt watersmix. Jitts ( 1959) showed that estuarine siltscan trap 80 to 90% of the high concentrationof phosphate present during periods of highfresh water runoff and later release it whenconditions are more stable, thereby contrib-uting to the high level of productivity char-acteris tically maintained in an estuary.Part of the explanation for the less dis-tinct seasonal cycle of phosphate in compari-son with nitrate is due to buffering action bythe above mechanism and the fact that sew-age entering the bay in a number of scat-tered places has a low N:P ratio. Twelveprimary treatment plants are situated onthe shores of the Raritan estuary. Theireffluents may tend to cancel temporal andregional differences in phosphate concentra-tions without markedly altering the distribu-tion of nitrate.

Ratio of Nitrate-Nitrogen toPhosphate-PhosphorusDiminishing concentrations of nitratefrom winter through summer agree withthe seasonal cycle in the sea. However,phosphate increased during this period, and,consequently, the ion ratio of nitrate to phos-phate shown in Figure 4 decreased. Redfield

( 1934) demonstrated a constant ratio of thetwo ions that holds for all oceans and ismaintained within certain limits regardlessof absolute concentrations. Departures havebeen discussed by Ketchum, Vaccaro, andCorwin ( 1958)) but the tremendous rangeobserved here, from 111.4:1 to 1.3: 1, indi-catcs that nutrient utilization, regeneration,and transport are quantitatively not thesame in the estuary and offshore. Reductionof river flow carrying concentrations of ni-trate and the aforcmen tioncd benthic releasemechanism for phosphate must be partiallyresponsible for the summer decrease in theratio. In addition, bacterial action on dis-

charged sewage may be more active duringsummer than winter, producing an absoluteincrease of phosphate and a drop in the ratioduring the warm seasons.It is postulated that a primary cause of thedecreasing ratio in Raritan Bay is a seasonalchange in the relative rates of nitrate andphosphate regeneration. At the primary pro-ducer level, algal phosphatases dephospho-rylate organic phosphorus in phytoplanktontissue yielding orthophosphate when theplants die ( Matsue 1949). Enzymes actingin a similar nature on proteins to releasenitrate are not known. Consequently, rapiddecomposition of organic phosphorus couldbe partially responsible for reducing theNOS: PO4 ratio. During the seaward pro-gression of a dead estuarine planktont, re-generation returns relatively more inorganicphosphorus than nitrogen to estuarine circu-lation. Upon reaching the ocean, the remainsof the organism are higher in nitrogen thanphosphorus in comparison with its composi-tion at the time of death within the estuary.Animal feeding and digestion may well beinvolved in producing high summer phos-phate concentrations. This is an extensionof Newcombes (1940) hypothesis attributingshort-term changes in phosphate content ofChesapeake Bay waters to the metabolicactivities of plankton, Copepods, comparedwith phytoplankton, are relatively rich innitrogen ( Sverdrup, Johnson, and Fleming1942, p. 234). Th e residual excess of plant-phosphorus taken in as food and passed outin the feces in the form of partially digestedand less complex molecules further dimin-ishes the NOs:P04 ratio. According to IIar-vey ( 1955), phosphorus in copepod fecalpellets dissolves in salt water and does notremain in voided plant particles. Dephos-phorylation by plant enzymes doubtlesstakes place in the digestive tract of a cope-pod, a process which could also occur in bot-tom animals. Metabolic orthophosphate isexcreted regardless of food intake and phos-phorus passes so rapidly through a copepodthat Conover, Marshall, and Orr ( 1959)found it necessary to correct for this factorwhen measuring the feeding rate of C&Z-nus finmarchicus with p2-tagged diatoms.


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HYDROGRAPHY OF A POLLUTED ESTUARY 29Coopers ( 1935) investigation showed thatphosphate liberated by decomposing zoo-plankton attained concentrations greaterthan the sum of phosphate initially presentin the water plus added plankton-phos-phorus. The excess was produced from dis-solved organic phosphorus initially presentin the water. We might expect, therefore,that the digestive, excretory, and deathprocesses of spring and summer planktonpopulations tend to promote initial regener-ation rates of phosphate with respect tonitrate.Generally higher bottom than surfacephosphate concentrations ( Table 1) mayindicate the significance of benthic popula-tions in control of the NOn:PO, ratio. Inaddition to the metabolic activity of benthicpopulations, stratification is probably due toa combination of differential rates of phos-phate removal from surface and bottomwaters and regeneration of plankton-phos-phorus in the lower part of the water column.Data arc not available to evaluate theserates, but their relative significance may beinferred. Absorption by phytoplankton insurface waters and regeneration in lowerlevels could produce phosphate stratifica-tion in the absence of turbulence, but bottomconcentrations as much as 1.95 pg-at/Lgreater than at the surface pcrsistcd duringsummer periods of tidal overmixing, andsimilar differences occurred during late fallwhen chlorophyll was present in occasionaltrace quantities. This indicates that factorssuch as the metabolic activity of benthicorganisms may have contributed to theobserved vertical distribution of phosphate.Regeneration of phosphate in shallow mudbottom was suggested by Cooper ( 19X),and Stephenson ( 1949) observed phosphateemanating from the bottom of a pollutedestuary. Harvey (1955) mentioned thatautolysis of bacteria in sediments rclcasesconsiderable amounts of phosphate to inter-stitial water, and Riley ( 1941a, b), suggest-ing that a low N : P ratio is characteristic ofshallow regions, drew attention to decompo-sition of organic sediments at high summertemperatures.

Comparison with Other Areas- Low estuarine N :P ratios have been ob-served by a number of authors. High dis-solved phosphorus levels in Florida estu-aries rcportcd by Odum, et ak. (1955) andothers were ascribed to terrigenous and sew-age contributions. Sources of similar naturepertain to Raritan Bay, but it seems unlikelythat they alone could account for the tre-mcndous seasonal range of the ratio.Maximum surface nitrate concentrationsrecorded in Raritan Bay, excluding station 1,were 3 to 7 times higher than those obtainedin Long Island Sound (Riley and Conover1956)) Gcorges Bank (Riley 1941b), andFriday Harbor (Phifer and Thompson 1937).The lowest value recorded in Raritan Bay,2.8 pug-at/L at station 6, was still higher thanthe mean summer level in Long IslandSound; phosphate showed a lesser differ-ence, averaging about 1.5 to 2 times higherin Raritan Bay.Nash (1947) drew attention to the con-centrations of nutrients in Chesapeake Bay,but his Figure 44 for the lower portion of oneof its tributaries, the Patuxent River, showsthat nitrate is maintained at approximately1 pg-at/L, except during the spring whenvalues are several times higher. Accordingto Newcombe, Horne, and Shepherd ( 1939 ) ,phosphate ranges between 0.6 and 1.6 pug-at/L. In Narragansett Bay, concentrationsare less than 1 pug-at/L during winter andspring and generally range between 1.5 and4 pg-at/L in the summer (Pratt personalcommunication ) . Comparison of these val-ues with Table 1 demonstrates the extremerichness of plant nutrients in Raritan Bay.In spite of fertilization by pollutants, verti-cal eddy conductivity in the shallow andweakly stratified bay waters is apparentlysufficient to insure oxygenation at all levels.An almost complete absence of benthicalgae beneath the intertidal zone in RaritanBay may be indirectly associated with highersummer phosphate and nitrate levels thanwere found in the lagoons investigated byHulbert ( 1956a, b ) , J, Conover ( 1958 ) , andR. Conover ( 1961). A large portion of thebottom in each of these embayments is cov-ered with a dense algal mat in which Ulva


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30 HARRY P. JEFFRIESand C2ndophora abound. O&m, Kuenzler, KETCIIUM, B. I-1. 1950 . Hydrographic factorsand Xavier ( 1958) showed a high rate of involved in the dispersion of pollutants intro-Psz uptake by these forms which, according duced into tidal waters. J. Boston Sot. Civilto J. Conover ( 1958), have their major -. Eng., 37: 296314.1951a. The exchanges of fresh and saltgrowth period from spring through early water in a tidal estuary. J. Mar. Rcs., 10:autumn. 18-38.Rich nutrient supplies arising from natural -* 1951b. The flushing of tidal estuaries.Sewage and Industr. Wastes, 23: 198-208.and domestic sources coupled with a slug- -, R. F. VACCARO, AND N. CORWIN. 1958.gish circulation and efficient nutrient regcn- The annual cycle of phosphorus in New Eng-eration produce an environment capable of land coastal waters. J. Mar. Res., 17: 282-supporting dense biotic communities. Sub- 301.sequent papers discuss the zooplankton. MARMER, H. A. 1935. Tides and Currents inNew York Harbor. Spec. Publ. No. 111, U. S.Dept. of Commerce, Coast and Geodetic Sur-REFERISNCES vey, 198 pp.AYERS, J. C., B. II. KETCI-IUU, AND A. C. REDFIELD. MATSUE,~. 1949. Phosphate storing by a marine

1949. Hydrographic consideration relative to diatom. J. Fish. Inst. Japan, 2: 29. (In Jap-the location of scwcr outfalls in Raritan Bay. anese-referred to by Harvey, 1955).Woods Hole Oceanogr. Inst., Ref. No. 29-13. MULLIN, J, B., AND J. P. RILEY. 1955. The spcc-tropho tomctric determination of nitrate in nat-( Unpublished ms. )CARHITT, D. E., ANI) S. GOODGAL. 1954. Sorption ural water with particular reference to seawater. Analytica Chimica Acta, 12 : 464-480.reactions and some ecological implications.Deep Sea Res., 1: 224-243. NASII, C. B. 1947. Environmental characteristicsCONOVER, J.T. 1958 . Seasonal growth of benthic of a river estuary. J, Mar. Res., 6: 147-174.NEWCOUBE, C. L. 1940. Studies on the phos-marine plants as related to environmental fac-tors in an estuary. Publ. Inst. Mar. Sci. Univ. phorus content of the estuarine waters of Ches-Texas, 5: 97-147. apcakc Bay. Proc. Amer. Phil. Sot., 83: 621-CONOVER, R. J. 1961 . A study of Charlestown 630.and Green Hill ponds, Rhode Island, Ecology, -, W. A. HORNE, AND B.B. SHEPI-LEI~D. 1939.42 : 119-140. Studies on the physics and chemistry of estu--, S. M. MAI~SIIALL, AND A. P. Onn. 1959. arine waters in Chesapeake Bay. J. Mar. Res.,Feeding and excretion of Calanus finmarchicus 2: 87-116.with reference to the possible role of zooplank- ODW, E. P., E. J. KUENZLER, AND M. XAVIER.ton in the mineralization of organic matter. 1958. Uptake of P32 and primary productivityWoods Hole Oceanogr, Inst., Ref. No. 59-32, in marine benthic algae. Limnol. Oceanogr.,12 pp. ( Unpublished ms. ) 3 : 340-348.Coor~:n, L. II. N. 1935. The rate of liberation of ODUM,H.T.,J.B. LACKEY, J. HYNES,AND N. MAR-phosphate in sea water by the breakdown OF SIIALL. 1955 . Some red tide characteristicsplankton organisms. J. Mar. Biol. Assoc., 20: during 1952-54. Bull. Mar. Sci. Gulf and197-200. Caribbean, 5 : 247-258.1938. Redefinition of the anomaly of PATTEN, B. P. 1959 . The diversity of species in--. the nitrate-phosphate ratio. J. Mar. Biol. net phytoplankton of the Raritan estuary.Assoc., 23: 179. Ph.D. dissertation, Rutgers University Library.-. 1951. Chemical propcrtics of the sea -* 1961 . Ncgentropy flow in communitieswater in the neighborhood of the Labadie Bank. of plankton. Limnol. Oceanogr., 6: 26-30.J. Mar. Biol. Assoc., 30: 21-26. PI-IIFER, L. D., AND T. G. TIIOMPSON. 19%'. Sea-DIXON, W. J,, AND F. J. MASSEY. 1957. Introduc- sonal variations in the surface waters of Santion to Statistical Analysis. McGraw-Hill Book Juan Channel during the five-year period, Jan-Co., New York, 488 pp. uary 1931 to Dcccmbcr 30, 1935. J. Mar.HARVEY, I-I. W. 1955. The Chemistry and Fcr- Res., 1: 34-53.tility of Sea Waters. Cambridge Univ. Press, REDFIELD, A. C. 1934. On the proportions of224 pp. organic derivatives in sea water and their rela-HULBEHT, E. M. 1956a. The phytoplankton of tion to the composition of plankton. In: JamesGreat Pond, Massachusetts. Biol. Bull., 110 Johnstone Memorial Volume, pp. 176-192, Liv-( 2 ) : 157-168. erpool Univ. Press, 348 pp.19561). Distribution of phosphorus in RILEY, G. A. 194la. Plankton studies III. LongTeat Pond, Massachusetts. J. Mar. Res., 15: Island Sound. Bull, Bingham Oceanogr. Coll.,

181-192. 7(3): l-93.JITTS, II. R. 1959 . The adsorption of phosphate 1941b. Plankton studies IV. Gcorgesby cstuarinc bottom deposits. Australian J. xik. Bull. B ingham Oceanogr. Coll., 7( 4) :Mar. Freshw. Res., 10: 7-21. l-73.


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HYDROGRAPHY OF A POLLUTED ESTUARY 31-> AND S. M. CONOVER 1956. Oceanography . SVEIIDRUP, I-1. U., M. W. JOHNSON, AND R. H.of Long Island Sound, 1952-1954 III. Chcmi- FLEMING. 1942. The Oceans, Their Physics,cal oceanography. Bull. Bingham Oceanogr.COIL, 15: 47-61. Chemistry, and General Biology. Prentice-RUDOLFS,W., AND A. H. FLETCHER. 1951. Re- Hall, New York, 1087 pp.

port of status of the Raritan River and Bay and UDELL, H.1951. Bacterial pollution of Raritan

effects of discharging into the bay mixed efflu- and Lower Bays and its relation to shellfish.ents. Mimco rept,, Dept. of Sanitation and Typcwrittcn rept., Fed. Security Agency, Publ.Div. of Environmental Sanitation, New Jcrscy Health Serv.State Dept. of Health. WATTENBERG, H. 1937. Methoden zur Bestim-STEPHENSON, W. 1949. Certain effects of agita- mung von Phosphat, Silikat, Nitrit, Natrat undtion upon the release of phosphate from mud. Ammoniak im Seewasser. Rapp. Proc. Verb.J. Mar. Biol. Assoc. U. K., 28: 371-380. Cons. Int. Explor. Mer, 103: 4-26.

Raritan Bay Paper - Polluted Estuary

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