Marine Pollution Bulletin

Transcription

1 Mrine Pollution Bulletin 6 ( Contents lists ville t ScienceDirect Mrine Pollution Bulletin journl homepge: The Boston Hror Project, nd lrge decreses in lodings of eutrophiction-relted mterils to Boston Hror Dvid. Tylor * Environmentl Qulity Deprtment, Msschusetts Wter Resources Authority, 1 First Avenue, Chrlestown Nvy Yrd, Boston, MA 19, USA rticle Keywords: Wstewter Nutrients Lodings Eutrophiction Boston Hror info strct Boston Hror, y estury in the north-est USA, hs recently een the site of one of the lrgest wstewter infrstructure projects conducted in the USA, the Boston Hror Project (BHP. The BHP, which ws conducted from 1991 to, ended over century of direct wstewter tretment fcility dischrges to the hror. The BHP cused the lodings of totl nitrogen (TN, totl phosphorus (TP, totl suspended solids (TSS nd prticulte orgnic cron (POC to the hror, to decrese y etween 8% nd 9%. Approximtely one-third of the decreses in TSS nd POC lodings occurred etween 1991 nd 199; the remining two-thirds, etween 1995 nd. For TN nd TP, the ulk of the decreses occurred etween 1997 or 1998, nd. Ó 9 Elsevier Ltd. All rights reserved. 1. ntroduction Eutrophiction or orgnic enrichment (Nixon, 1995 cused y elevted inputs of rective orgnic mtter nd/or nutrients (principlly N nd P, hs een identified s thret to costl qutic ecosystems worldwide (Scvi nd Bricker, 6; Schindler, 6; Cloern, 1. Mny of the wstewter infrstructure projects conducted in the USA over the pst 5 yers hve imed to reduce the lodings of these mterils to these systems (Conley et l., 9. Mny of the erly projects focused on the removl of solids nd rective orgnic mtter from the wstewter dischrged to these systems (e.g. Alert, 1987; Brosnn nd O She, More recently, the projects hve imed to lso remove nutrients, in certin cses P, nd in others, N (e.g. Jworski et l., 7; Mllin et l., 5. Certin of the projects hve employed ocen outflls to minimize the eutrophiction-effects of the wstewter dischrges (e.g. Smith et l., Boston Hror, y estury in the north-est USA, hs recently een the site of one of the lrgest wstewter infrstructure projects conducted in the USA, the Boston Hror Project (BHP (Breen et l., 199; Brocrd et l., 199. Before the BHP the totl lodings of totl nitrogen (TN nd totl phosphorus (TP to the hror were mong the highest reported for ys or esturies in the USA (Dettmnn, 1; Kelly, The two wstewter tretment fcilities (WWTF s tht t the time dischrged to the hror, nd lter ecme the focus of the BHP, contriuted >9% of these elevted lodings (Aler nd Chn, * Tel.: ; fx: E-mil ddress: dtylor@mwr.stte.m.us 199. The hror lso showed symptoms of eutrophiction tht were typicl of highly-enriched, ut well flushed y (Diz et l., 8; Mciolek et l., 6; Tylor, 6; Gilin et l., 1997; the verge hydrulic residence time of the hror is 5 7 d(stolzench nd Adms, This pper documents the chnges in the lodings of eutrophiction-relted mterils to the hror over the course of the BHP, to quntify the contriution of the BHP to the chnges. The pper ddresses only the lodings to the hror. Diz et l. (8, Ovitt et l. (7, Mciolek et l. (6, Tylor (6, Tucker et l. (5, Gilin et l. (1997 nd others, hve documented the chnges to the hror itself.. Overview of the BHP The BHP involved five mjor construction milestones, which were completed etween Decemer 1991 nd Septemer. Fig. 1 provides schemtic of the five milestones nd the chnges in the loctions of the WWTF sludge nd effluent dischrges to the hror over the course of the BHP. Bsed on these chnges, the study could e prtitioned into four loding periods (Periods V. During Period, which here represents the period efore the BHP, the hror received primry- (1 treted effluent plus sludge generted y the 1 -tretment process, from two WWTF s. The Deer slnd (D WWTF dischrged effluent nd sludge to the North Hror (Fig.. The Nut slnd (N WWTF dischrged effluent to the South Hror nd sludge to the North Hror. The effluent dischrges from the D WWTF verged m d 1 ; from the N WWTF, they verged m d 1. The North Hror lso received dischrges from 6 comined sewer overflows (CSO s. 5-6X/$ - see front mtter Ó 9 Elsevier Ltd. All rights reserved. doi:1.116/j.mrpolul.9.1.6

2 61 D.. Tylor / Mrine Pollution Bulletin 6 ( Fig. 1. Schemtic of the study period showing the chnges in the loctions of the WWTF sludge nd effluent dischrges, the pproximte timing of the five construction milestones of the BHP, nd the four loding periods (Periods V. n Decemer 1991, the dumping of the sludge from the two fcilities to the hror ws ended. This ws the first construction milestone of the BHP, nd lso mrked the strt of Period. On this dte the sludge from oth of the WWTF s ws redirected to new sludge pelletiztion plnt for conversion into fertilizer. The liquid presste from the sludge ws then returned to the N WWTF for 1 -tretment, nd then dischrge from the N WWTF outflls. During Period, which extended from 1 Jnury 199 to 6 April 1998, the hror received dischrges of effluent lone from the two WWTF s, nd t the sme loctions s in Period. n July 1995 new 1 -tretment fcility ws completed t the D WWTF; this ws the second milestone of the Project. The third milestone, the upgrde to secondry ( tretment t the D WWTF, ws strted in July 1997, nd completed in Mrch Seven dditionl CSO s tht dischrged to the hror were eliminted during Period. The fourth milestone of the BHP ws completed on 6 April 1998, when the wstewter (+ sludge presste formerly treted t the N WWTF ws diverted through the upgrded D WWTF for dischrge to the mouth of the hror. This inter-islnd (or diversion mrked the strt of loding Period. During this loding period, the hror received WWTF dischrges from the D WWTF lone, nd the effluent ws -treted. Two dditionl CSO s were eliminted during Period. The finl milestone of the BHP ws completed on 6 Septemer, when the now-comined nd -treted effluent from the D WWTF ws diverted 15-km offshore for diffusion into the ottom-wters of Msschusetts By. This offshore (or diversion ended over century of direct WWTF dischrges to the hror, nd lso mrked the completion of the BHP. During the next 7 yers, represented y Period V, the effluent from the D WWTF ws dischrged through n ocen outfll-diffuser system locted on the sefloor of Msschusetts By, t wter-depth of m. The effluent dischrged from the outfll during the summers entered the wter-column of the y elow the sesonl pycnocline. A further 11 CSO s were eliminted during Period V.. Methods Lodings nd inflows to the hror were mesured from the two WWTF s, the four lrgest triutry rivers, nd the non-point (NP sources tht dischrged directly to the hror, from 199 to 7. Emphsis ws plced on the mesurement of the flows/lodings from the WWTF s nd rivers; these eing the sources responsile for y fr the ulk of the lodings of eutrophiction-relted mterils to the hror (Aler nd Chn, 199. Effluent flows from the two WWTF s were mesured t the points of exit of the flows from the WWTF s. 7% nd 88% of the effluent dischrged from the D nd the N WWTF s, nd 1% of the sludge dischrged from oth fcilities, were ssumed to enter the hror. Previous studies ssumed entry of 1% of oth the effluent nd the sludge from oth fcilities to the hror (e.g. Aler nd Chn, 199. The estimtes of 7% nd 88% were derived from prticle dispersion modeling conducted efore the BHP, y Signell nd Buttmn (199. During the period fter the completion of the project, % of the effluent dischrged from the y outfll ws ssumed to re-enter the hror. This estimte, which is likely to e n over-estimte, ws computed ssuming the wstewter dischrged from the y outfll ws dispersed eqully through 6, nd tht the proportion of the effluent entering the hror ws proportionl to the contriution mde y the mouth of the hror, to the circumference of circle centered on the y outfll. Effluent flows from oth WWTF s were mesured continuously. Flows from the D WWTF were mesured using mgnetic flow

3 D.. Tylor / Mrine Pollution Bulletin 6 ( Fig.. Mp of Boston Hror showing the loctions of WWTF nd CSO dischrges to the hror efore the BHP. Also shown re the loctions t which the inflows nd the lodings to the hror were monitored during this study. meters with n error of. 1.%. At the N fcility, flows were mesured using Accusonic level indictors, with n error of 1 15%. At the D WWTF, effluent nutrient concentrtions were mesured once per week; t the N WWTF they were mesured once per month. At oth fcilities, sludge nutrients concentrtions were mesured once per month. At oth fcilities, concentrtions of totl suspended solids (TSS in effluent were mesured once per dy; sludge TSS concentrtions were mesured once per week. Effluent prticulte orgnic cron (POC concentrtions were computed for oth fcilities ssuming POC concentrtions in 1 -treted effluent verged.1 mg l 1, nd in -treted effluent,.6 mg l 1 (Butler et l., POC concentrtions were ssumed to e.7 times the mesured TSS concentrtions. TN-concentrtions in the effluent nd sludge were clculted y summing the mesured concentrtions of totl Kjeldhl nitrogen

4 61 D.. Tylor / Mrine Pollution Bulletin 6 ( LOADNG PEROD V 1 o o - LOADNGS TSS -1 ( TON D LOADNGS POC LOADNGS TN -1 ( TON D -1 ( TON D WWTF SLUDGE NP SOURCES RVERS WWTF EFFLUENT 6 LOADNGS TP -1 ( TON D Fig.. Annul verge totl lodings of TSS, POC, TN nd TP, prtitioned y source, Verticl rrows show the yers the five construction milestones were either strted or completed. = sludge dumping ended; 1 = completion of the new primry tretment fcility t D WWTF; = strt of the phse-in of secondry tretment t D; = completion of the inter-islnd diversion; = completion of the diversion of the D WWTF flows offshore. (TKN nd nitrte + nitrite (NO +. Effluent nd sludge concentrtions of TKN were mesured ccording to Clesceri et l. (1998, Method 5-N; NO + concentrtions were mesured using Method 5. (Clesceri et l., TP concentrtions were mesured using Method 65.1; TSS concentrtions were mesured using Method 16. (oth methods from Clesceri et l., River flows to the hror were otined from USGS guging sttions (the USGS 8-digit guging sttion D s re shown in Fig.. For the Chrles, Mystic nd Weymouth Weir rivers, where the guging sttions were locted ove the river hror junctions, the guged flows were prorted y the frction of the totl re of ech wtershed served y ech guging sttion. For the Neponset River, where the guge ws locted right t the river hror junctions, the guged flows were the flows used to estimte the flows nd lodings. For the Chrles, Neponset nd Mystic Rivers, the wter smples for chemicl nlyses were collected t the river hror junctions, once per week, t.5 m depths. TN nd TP concentrtions were

5 D.. Tylor / Mrine Pollution Bulletin 6 ( LOADNG PEROD V 1 o o NFLOWS FRESHWATER ( x 1 6 m D T N:TP LOADNGS TSS:POC LOADNG S WWTF SLUDGE NP SOURCES RVERS WWTF EFFLUENT ALL SOURCES 199 Fig.. Annul verge totl freshwter inflows nd nnul verge TSS:POC nd TN:TP lodings over the study period. The rtios of the lodings re for ll lodings comined; the freshwter inflows re prtitioned y source. Rtios re y weight. mesured on unfiltered smples, ccording to Solrzno nd Shrp (198,. Smples for TSS nd chlorophyll nlyses were filtered through nucleopore filters. TSS concentrtions were determined ccording to Clesceri et l. (1998, Method 16.. Chlorophyll concentrtions were mesured ccording to Holm-Hnson et l. (1965. River POC concentrtions were clculted from the concentrtions of chlorophyll mesured in the rivers, ssuming POC = chl + (1.9/.17, r =.7 (this reltionship ws derived from concentrtions of POC nd chlorophyll mesured in the Chrles River, MWRA unpulished dt. For the Weymouth Weir River, the smllest of the rivers, concentrtions of TSS, POC, TN nd TP were ssumed to e s for the Neponset River. Averge CSO dischrges to the hror were estimted using the EPA SWMM Model., run using typicl-yer rinfll (roughly equivlent to 199 rinfll, nd the CSO infrstructure present ech yer (MWRA, unpulished dt. CSO TN, TP nd TSS concentrtions were ssumed to e 91 mg m, 8 mg m, nd 1, mg m ; these were the verge concentrtions mesured in the CSO s in 1997 (MWRA, unpulished dt. CSO POC lodings were ssumed to e.7 times the TSS-lodings. The flows nd the lodings from the non-cso, non-point (NP sources were estimted using rtios of the inputs from these sources reltive to the inputs from the rivers (from Aler nd Chn, 199. The verge monthly river flows/lodings mesured during the current study were multiplied y these rtios to estimte the inputs from the non-cso, non-point (NP sources through the study. The specific rtios employed were.7:1 for freshwter inflows, nd.:1,.:1,.61:1 nd.7:1 for TSS, POC, TN nd TP, respectively.. Results.1. Chnges in lodings, nd the mjor milestones of the BHP The nnul verge lodings of TSS, POC, TN nd TP to the hror, summed for ll sources comined, decresed over the study (Fig.. The decreses coincided with the dtes of completion of the vrious construction milestones of the BHP. The nnul verge TSS- nd PC-lodings to the hror decresed etween 1991 nd 199, leveled off through 199, nd then declined gin through 1. The decreses etween 1991 nd 199 coincided with, nd

6 61 D.. Tylor / Mrine Pollution Bulletin 6 ( Tle 1 Comprison of the verge (±1 SD lodings of TSS, POC, TN nd TP, nd inflows of freshwter to Boston Hror, during the four loding Periods. (n = months for Period, 76 months for Period, 8 months for Period, 88 months for Period V. Source Averge vlues during Period Difference etween Periods nd V V TSS (ton d 1 Comined WWTF + river + NPS 18 ± 7 ± 15 5 ± 18 1 ± 9 115( 89% <.5 WWTF effluent 7 ± 1 58 ± 8 15 ± 7 1 ± 1 71( 1% <.5 WWTF sludge ± 5 ( 1% <.5 Rivers 1 ± 8 11 ± 8 1 ± 1 8 ± 6 ( 5% <.5 NP sources ± 5 ± 6 ± ± (% POC (ton d 1 Comined WWTF + river + NPS 9.5 ± 1 55 ± 1 15 ± ( 95% 6. WWTF effluent 57 ± 1 8 ± 1 1 ± 5. ±.1 57( 1% 6.5 WWTF sludge 8 ± 8 8( 1% <.5 Rivers 5 ± 1 5 ± ± ± 1( % NP sources.5 ± 1 ± 1 1 ±.5 1 ± 1 1.5( 6% Totl nitrogen (ton d 1 Comined WWTF + river + NPS.8 ± ± 5.6. ± 5.. ± ( 8% 6.5 WWTF effluent 18. ±.. ± ±..8 ±. 17.( 96% <.5 WWTF sludge 1.6 ±.6 1.6( 1% <.5 Rivers.8 ±..5 ± ± 1.9. ± 1.8.( 1% NP sources 1. ± ± ±.8 1. ±.8.( 9% Totl phosphorus (ton d 1 Comined WWTF + river + NPS.6 ± 1.1. ±.77.1 ±..5 ±.1.5( 95% 6.5 WWTF effluent.9 ±.9. ± ±..5 ±..85( 99% 6.5 WWTF sludge.5 ±.1.5( 1% <.5 Rivers.15 ± ± ±.1.15 ±.9.(% NP sources.5 ±..5 ±..6 ±..5 ±..(% Freshwter inflows (1 6 m d 1 Comined WWTF + river + NPS. ± ± ± ± ( % 6.5 WWTF effluent.99 ±. 1. ±..7 ±.16. ±.1.96( 97% 6.5 WWTF sludge..( 1% Rivers 1.81 ± ± ± ±.99.8( 1% 6.5 NP sources.5 ±.16.5 ±.7.9 ±.. ±.8.1( % p (Mnn Whitney U test were cused y the ending of the sludge dischrges in 1991 (Milestone 1. The decreses in the TSS- nd POC-lodings etween 199/1995 nd 1 spnned the second through fifth milestones of the BHP. As cn e seen in the figure, decreses in WWTF-effluent lodings were responsile for the decreses in the lodings during the midstudy. The strt of the decreses in the TSS nd POC lodings in 199/1995 coincided with the completion of the new 1 -tretment fcility t the D WWTF. The nnul verge TN- nd TP-lodings to the hror remined elevted from 199 to 1997 or 1998, nd then declined through 1. The strt of the decrese in the TN lodings etween 1998 nd 1999 coincided with the diversion of the N WWTF flows through the D WWTF. The strt of the decrese in the TP-lodings in 1997 coincided with the strt of the phse-in of -tretment t the D WWTF. The decreses in the TN- nd TP-lodings from 1997/1998 to 1 were cused lrgely y decreses in the WWTF-effluent lodings to the hror. Unlike for TSS nd POC, the ending of the sludge dischrges hd little impct on the totl lodings of TN nd TP. For TN nd TP, s for TSS nd POC, the nnul verge lodings during the lst 7 yers of the study were smll frction of the lodings during the yers the hror received the WWTF dischrges. The hror lso experienced decrese in totl inflows of freshwter over the study (Fig.. The decrese ws smll compred to the decreses for TSS, POC, TN nd TP, ut ws evident etween nd 1. The difference ws not s lrge s for the other vriles, ut during the lst 7 yers of the study the nnul verge inflows were consistently lower thn during the yers the hror received the WWTF dischrges. The verge TSS:POC nd TN:TP rtios of the lodings to the hror incresed over the study. The verge TSS:POC lodings remined low from 199 to 1998, incresed etween 1998 nd 1999, nd then remined elevted through 7. For TN:TP, the verge lodings incresed from 199 to, incresed more ruptly etween nd 1, nd then remined elevted through the end of the study... Totl chnges, nd the contriutions of the WWTF lodings Tle 1 compres the verge lodings nd inflows to the hror, for ll sources comined nd prtitioned y source, for ech of the four loding periods. For ll seven prmeters, the verge inputs during Period V were significntly different from the verges during the seline (Period (p <.5, Mnn Whitney U- test. For TSS nd POC, the decreses in the lodings etween the two periods totled 115 ton d 1 (89% nd 87.5 ton d 1 (95%. Decreses in WWTF lodings were responsile for 111 ton d 1 (or 97%, nd 69 ton d 1 (or 9% of the respective decreses. For oth prmeters, the ending of the sludge dischrges ccounted for out one-third of the decreses; the decreses in the effluent lodings lter in the project, ccounted for the remining twothirds. A ckground decrese in river inflows contriuted ton 1 or c. % of the decrese in the TSS lodings. During Period V, the verge TN- nd TP-lodings to the hror were 19.6 ton d 1 (or 8% nd.5 ton d 1 (or 95%, lower thn during Period. Decreses in WWTF lodings ccounted for 18.8 ton d 1 or 96%, nd. ton d 1 or 1% of the respective decreses. For oth nutrients, the decreses in the effluent lodings contriuted 88% of the decreses. The decreses in the sludge lodings contriuted 8% nd 11%, respectively. The totl inflows of freshwter to the hror during Period V were m d 1 or % lower thn during Period. The ending of the WWTF dischrges in ccounted for

7 D.. Tylor / Mrine Pollution Bulletin 6 ( TSS LOADNGS (TOND V 5 POC LOADNGS (TOND V TN LOADNGS (TOND -1 1 V WWTF EFFLUENT RVERS NP SOURCES WWTF SLUDGE 8 TP LOADNGS (TOND -1 FRESH WATER NFLOWS ( X 1 6 M D V V LOADNG PEROD Fig. 5. Comprison of the verge TSS, POC, TN nd TP lodings, nd the verge freshwter inflows etween the four loding periods. The horizontl lines indicte the sttisticl significnce of the differences in mens etween periods (tested using the Fisher s LSD test. The verges with seprte lines were significntly different from one nother (p < m d 1 or 68% of the decrese. A ckground decrese in river inflows unrelted to the BHP, contriuted n dditionl m d 1 or 6% of the decrese. For only the river inflows nd the river lodings of TSS, were the verge inputs from sources other thn the WWTF s different etween Periods nd V... Differences in lodings etween the four loding periods Figs. 5 nd 6 compre the verge lodings nd rtios of the lodings during the four loding periods. As cn e seen from Fig. 5, the ulk of the decreses in the TSS nd especilly the POC lodings occurred erly in the study, nd etween Periods nd, nd to lesser extent, etween Periods nd. For TN nd, to lesser extent for TP, the decreses occurred lter in the study, nd etween Periods nd, nd especilly etween Periods nd V. Most of the decreses in the totl freshwter inflows to the hror occurred etween Periods nd V nd to some extent etween Periods nd. The ulk of the increse in the TSS:POC lodings occurred during the mid-study, nd etween Periods nd. For the verge TN:TP lodings, most of the increse occurred lter in the study, nd etween Periods nd V. The sizes

8 D.. Tylor / Mrine Pollution Bulletin 6 ( LOADNGS POC 1 TSS : V ALL SOURCES TN : TP LOADNGS V LOADNG PEROD Fig. 6. Comprison of the verge TSS:POC nd TN:TP lodings etween the four loding periods. Detils s in Fig. 5. nd the comintions of the lodings received y the hror were quite different during the four periods. The dominnt sources of the inputs to the hror lso shifted over the course of the study. During Period, the WWTF s contriuted most, nd etween 8% nd 96% of the totl TSS-, POC-, TNnd TP-lodings to the hror. They lso contriuted 1% of the totl inflows of freshwter. During Period V, the rivers + NP sources contriuted 8% or more of the, in turn, much smller totl lodings of these mterils to the hror. They contriuted 98% of the totl freshwter inflows to the hror. As cn e seen from Fig. 5, the differences in the WWTF lodings were lso lrgely responsile for the differences in the totl lodings oserved etween periods... Contriutions y the different milestones Fig. 7 compres the contriutions of ech of the milestones of the BHP to the chnges in the WWTF (sludge + effluent lodings to the hror. The first milestone, the ending of the sludge dumping, contriuted % of the totl decreses in the WWTF lodings of TSS nd POC. t contriuted 1% for TN nd TP. The new 1 -tretment fcility completed t the D WWTF, ccounted for 1.6% nd.8% of the totl decreses in the WWTF TSS- nd POC-lodings, nd.5% for TN nd TP. The upgrde to -tretment t the D fcility contriuted 17% nd 19% of the decreses in the WWTF lodings of POC nd TP, nd 5% nd 8% for TSS nd TN. The inter-islnd diversion contriuted 15%, %, 19% nd 8% to the decreses in the WWTF lodings of TSS, POC, TN nd TP. The diversion of the D WWTF dischrges offshore contriuted 1% nd 19% of the decreses in the TSS nd POC lodings, nd 6% nd % for TN nd TP. 5. Discussion 5.1. Comprisons with other systems Fig. 8 compres the chnges in the totl lodings of TN nd TP experienced y Boston Hror, with the chnges in lodings experienced y five other ys nd esturies sujected to wstewter projects. ncluded in the figure for references re the lodings to Chespeke By, Delwre By, Nrrgnsett By, Ochlockonee By, nd Tmp By. Note: the lodings for the Ptuxent Estury include only the lodings from the WWTF s nd from the Ptuxent River. The lodings to the New River Estury include only the WWTF lodings. Detils of the wstewter projects ssocited with ech of the systems re provided in Tle. The lodings of TN nd TP to Boston Hror efore the BHP were either the highest or second highest mong the systems shown in Fig. 8. The pre-project lodings of TN to the hror were 1.9 the equivlent lodings to the Potomc Estury nd Hillsorough By, nd 1 the lodings to Kneohe By. The TP lodings to the hror efore the BHP were.9 nd 1 the equivlent lodings to the Potomc Estury nd Kneohe By, respectively. The decreses in the lodings of TN nd TP experienced y the hror were lso the gretest mong the six systems tht were sujected to wstewter projects, nd for which pre- nd postloding dt were ville. The decreses in the TN-lodings to the hror were 8.5,.9 nd 17. the decreses to the Potomc Estury, Hillsorough By nd Kneohe By, respectively. The decreses in the TP-lodings to the hror were 1.1 nd 1.1 the decreses to the Potomc Estury nd to Kneohe By. The fct tht the decreses in the TN nd TP lodings to the hror were somewht simultneous nd rpid ws s for Kneohe By, nd proly lso for the New River Estury. They ws however quite different from the decreses experienced y the Ptuxent nd Potomc esturies. For oth of these systems, the lodings of TP to the systems decresed first, nd then decde or more lter, the lodings of TN decresed. The decreses in the TN- nd TPlodings to the hror spnned yers; they spnned 1 yers nd 1 15 yers, respectively for the Potomc Estury. 5.. Chnges within the hror Bsed on the chnges tht followed the smller decreses in lodings experienced y Hillsorough By (Johnssen nd Lewis, 199, Kneohe By (Smith et l., 1981, the New River Estury (Mllin et l., 5 nd the Potomc Estury (Jworski et l., 7, chnges hve likely lso occurred in Boston Hror. Much of the dt collected in the hror over the course of the BHP re

9 D.. Tylor / Mrine Pollution Bulletin 6 ( T P (% T N (% POC (% TSS (% o o 1 o o 1 o o Ochlockonee By Boston Hror (efore Potomc Estury (efore c Hillsorough By (efore Potomc Estury (fter c Hillsorough By (fter Nrrgnsett By Delwre By Boston Hror (fter Chespeke By d Ptuxent Estury (efore e Kneohe By (efore d Ptuxent Estury (fter f Tmp By e Kneohe By (fter g New River Estury (efore g New River Estury (fter Ochlockonee By Boston Hror (efore Potomc Estury (efore c Hillsorough By (efore Potomc Estury (fter c Hillsorough By (fter Nrrgnsett By Delwre By Boston Hror (fter Chespeke By d Ptuxent Estury (efore e Kneohe By (efore d Ptuxent Estury (fter TN LOADNGS ( MG M - Y ,796 ( -57% -6,1 ( -5% -,655 (wstewter dt only -1,7 ( -19% -8 ( -55% -1,55 ( -% -9,79 ( -% TP LOADNGS ( MG M - Y -1-66,65 ( -8% dt not reported dt not reported dt not reported -1,6 ( -9% 1 o o - MLESTONES f Tmp By e Kneohe By (fter g New River Estury (efore g New River Estury (fter -1, ( -79% -91 (wstewter dt only Fig. 7. Percent contriutions of the five construction milestones of the BHP to the totl decreses in the WWTF lodings of TSS, POC, TN nd TP to Boston Hror. still eing interpreted, ut the nlysis to dte hs identified numer of chnges. The verge concentrtions of TN nd TP, iomss of phytoplnkton, nd rtes of 1 C primry production in the wter-column Fig. 8. Comprison of the totl lodings of TN nd TP to Boston Hror efore nd fter the BHP, with the lodings to 1 other ys nd esturies. Nixon et l., 1996; Jworski et l., 7; c Johnssen nd Lewis, 199; d Test et l., 8; e Smith et l., 1981; f Greening nd Jnicki, 6; g Mllin et l., 5. of the hror hve ll decresed (Ovitt et l., 7; Tylor, 6. During summers, the concentrtions of dissolved oxygen in the Tle Comprison of the BHP nd the wstewter infrstructure projects ssocited with Hillsorough By, Kneohe By, New River Estury, Ptuxent Estury, nd the Potomc Estury. System Nture of infrstructure projects Dtes of projects Sources Boston Hror Termintion of sludge dumping, upgrde to o -tretment, nd diversion of WWTF 1991 Present study dischrges offshore Hillsorough By Upgrde to tertiry ( o, or denitrifiction tretment of the lrgest WWTF 197s Johnssen nd Lewis (199 Kneohe By Upgrde to o tretment t the two lrgest WWTF s Erly 197s Smith et l. (1981 Diversion of the upgrded dischrges offshore 1997/1998 New River Estury Upgrde to o tretment of c. 5% of WWTF dischrges, nd then diversion onto forested Mid-199s Mllin et l. (5 res Upgrde to o (denitrifiction tretment of remining 5% of WWTF dischrges Mid-199s Ptuxent Estury Upgrde to o -tretment 197s Test et l. (8 Upgrde to o -tretment Erly 199s Potomc Estury Upgrde to dvnced o -tretment t lrgest WWTF 197s Jworski et l. (7 Upgrde to o -tretment t lrgest WWTF Mid-199s

10 c d e f c d e f c d e f c d e f c d e f 618 D.. Tylor / Mrine Pollution Bulletin 6 ( COSTS x1 6 D ( U CONSTRUCTON S 1 15 COSTS TSS unpulished dt. The re of the hror ottom covered y mphipod tue mts hs decresed, nd the verge depth of the redox potentil discontinuity lyer in the sediments hs incresed (Diz et l., 8. At certin loctions in the North Hror, the rtes of oxygen uptke y the sediments, the rtes of denitrifiction within the sediments, nd the net fluxes of N nd P from the sediments hve decresed (Tucker et l., 5; Gilin et l., The orgnic content of the surfce sediments of the hror hs decresed (Tucker et l., 5, s hve the POC content nd TSS:POC rtios of the prticulte mteril in the hror wter-column (Tylor, Construction costs per unit decreses in lodings LOADNGS N DECREASE UNT PER COST ton y -1 ( x1 6 USD per x POC TN Fig. 9 compres the totl construction costs, nd the costs per unit decreses in WWTF lodings of TSS, POC, TN nd TP, for six different construction milestones. The BHP is represented y the sixth scenrio. The costs re for construction lone, nd re in 1 $USD. The totl costs for the scenrios rnged from $USD for the first scenrio to $USD for the sixth scenrio. The costs to decrese lodings per unit mount lso differed mong scenrios, depending on the mteril. For TSS nd POC, the first scenrio, the ending of the sludge dischrges lone, provided the lowest costs per unit decreses. For ll four mterils, the second nd third scenrios provided the highest unit costs; these scenrios included the new 1 -, or 1 + -tretment fcilities t the D WWTF, ut neither of the WWTF diversions. For TN nd TP, the lowest unit costs were provided y the fourth nd fifth milestones, tht included 1 -tretment plus one or oth of the diversions, ut no -tretment. 6. Disclimer This pper represents the opinions nd conclusions of the uthor nd not necessrily those of the Msschusetts Wter Resources Authority TP Acknowledgements Grteful thnks re extended to K. Key nd W. Leo for reviewing erly drfts of this pper. Thnks re lso due to K. Coughlin for setting up nd mnging the river smpling, nd for providing dt mngement nd QA/QC. L. Ducott, N. O Neill, Kery Berger nd others conducted the river monitoring. L. Ducott, N. O Neill, nd N. McSweeney provided lortory QA/QC. D. Hersh, P. Rlston nd others hve mnged the dt. o o o + 1 Fig. 9. Totl costs, nd the costs per unit decreses in WWTF-lodings to Boston Hror, for six different construction scenrios. The scenrios include comintions of the five construction milestones undertken s prt of the BHP. ottom-wters of especilly the deeper, more esturine portions of the hror, hve incresed (Tylor, 6. The diversity of the enthic inverterte communities of the hror hs incresed (Mciolek et l., 6, nd the segrss eds tht once covered much of the hror sefloor hve shown erly signs of recovery (Msschusetts Division of Mrine Fisheries, + - o o + 1 BHP References Aler, M., Chn, A.B., 199. Sources of contminnts to Boston Hror: revised loding estimtes. ENQUAD Report No , Msschusetts Wter Resources Authority, Boston. Alert, R.C., The historicl context of wter qulity mngement for the Delwre Estury. Esturies 11, Breen, C., Vittnds, J., O Brien, D., 199. The Boston Hror Project; history nd plnning. Civil Engineering Prctice 9, 11. Brocrd, D.N., vn Wheele, B.J., Willimson, L.A., 199. The new Boston outfll. Civil Engineering Prctice 9, 8. Brosnn, T.M., O She, M.L., Long-term improvements in wter qulity due to sewge tement in the lower Hudson River. Esturies 19, Butler, E., Higgins, M., Chipell, J., Sung, W., Deer slnd effluent chrcteriztion studies, Jnury 1995 Decemer ENQUAD Report No , Msschusetts Wter Resources Authority, Boston. Clesceri, L.S., Greenerg, A.E., Eton, A.D., Stndrd Methods for the Exmintion of Wter nd Wstewter, th Edition. Americn Pulic Helth Assocition, Americ Wter Works Assocition nd Wter Environment Federtion, p. 15. Cloern, J.E., 1. Our evolving conceptul model of the costl eutrophiction prolem. Mrine Ecology Progress Series 1, 5.

11 D.. Tylor / Mrine Pollution Bulletin 6 ( Conley, D.J., Perl, H.W., Howrth, R.W., Boesch, D.F., Seitzinger, S.P., Hvens, K.E., Lncelot, C., Likens, G.E., 9. Controlling eutrophiction: nitrogen nd phosphorus. Science, Dettmnn, E.H., 1. Effect of wter residence time on nnul export nd denitrifiction in esturies: model nlysis. Esturies, Diz, R.J., Rhods, D.C., Blke, J.A., Kropp, R.K., Key, K.E., 8. Long-term trends in enthic hitts relted to reduction in wstewter dischrges to Boston Hror. Esturies nd Costs 1, Gilin, A.E., Hopkinson, C.S., Tucker, J., Benthic metolism nd nutrient cycling in Boston Hror nd Msschusetts By, Msschusetts. Esturies, 6 6. Greening, H., Jnicki, A., 6. Towrd reversl of eutrophic conditions in sutropicl estury: wter qulity nd segrss response to nitrogen loding reductions in Tmp By, Florid, USA. Environmentl Mngement 8, Holm-Hnson, O., Lorenzen, C.J., Holmes, R.W., Stricklnd, J.D.H., Fluorometric determintion of chlorophyll. CES/CEM nterntionl Council for the Explortion of the Se/Conseil nterntionl pour l Explortion de l Mer, 15. Jworski, N.A., Romno, W., Buchnn, C., Jworski, C., 7. The Potomc River Bsin nd its Estury: Lndscpe Lodings nd Wter Qulity Trends, Aville from the Potomc ntegrtive Anlysis Online Collection t: Johnssen, J.O.R., Lewis, R.R., 199. Recent improvements of wter qulity nd iologicl indictors in Hillsorough By, highly impcted sudivision of Tmp By, Florid, USA. Science of the Totl Environment Supplement, Kelly, J.R., Nitrogen flow nd the interction of Boston Hror with Msschusetts By. Esturies, Mciolek, N.J., Diz, R.J., Dhlen, D.T., Willims,. P., 6. 5 Boston Hror enthic monitoring report. ENQUAD Report No. 6-, Msschusetts Wter Resources Authority, Boston. Mllin, M.A., Mcver, M.R., Wells, H.A., Prsons, D.C., Johnson, V.L., 5. Reversl of eutrophiction following sewge tretment upgrdes in the New River Estury, North Crolin. Esturies 8, Nixon, S.W., Costl mrine eutrophiction: definition, socil cuses, future concerns. Opheli 1, Nixon, S.W., Ammermn, J.W., Atkinson, L.P., Berounsky, V.M., Billen, G., Boicourt, W.C., Boynton, W.R., Church, T.M., Ditoro, D.M., Elmgren, R., Grer, J.H., Gilin, A.E., Jhnke, R.A., Owens, N.J.P., Pilson, M.E.Q., Seitzinger, S.P., The fte of nitrogen nd phosphorus t the lnd se mrgin of the North Atlntic Ocen. Biogeochemistry 5, Ovitt, C.A., Hyde, K.J.W., Keller, A.A., 7. Production ptterns in Msschusetts By with outfll reloction. Esturies nd Costs, 5 6. Scvi, D., Bricker, S.B., 6. Costl eutrophiction ssessment in the United Sttes. Biogeochemistry 79, Schindler, D.W., 6. Recent dvnces in the understnding nd mngement of eutrophiction. Limnology nd Ocenogrphy 51, Signell, R.P., Buttmn, B., 199. Modeling tidl exchnge nd dispersion in Boston Hror. Journl of Geophysicl Reserch 97, Smith, S.V., Kimmerer, W.J., Lws, E.A., Brock, R.E., Wlsh, T.W., Kneohe By sewge diversion experiment: perspectives on ecosystem responses to nutrient perturtion. Pcific Science 5, Solrzno, L., Shrp, J.H., 198. Determintion of totl dissolved nitrogen in nturl wters. Limnology nd Ocenogrphy 5, Solrzno, L., Shrp, J.H., 198. Determintion of totl dissolved phosphorus nd prticulte phosphorus in nturl wters. Limnology nd Ocenogrphy 5, Stolzench, K.D., Adms, E.E Contminted Sediments in Boston Hror. Msschusetts nstitute for Technology Se Grnt Puliction, Cmridge, USA, p. 17. Tylor, D.., 6. Five yers fter trnsfer of Deer slnd flows offshore: n updte of wter-qulity improvements in Boston Hror. ENQUAD Report No. 6-16, Msschusetts Wter Resources Authority, Boston. Tucker, J., Kelsey, S., Gilin, A.E., Hopkinson Jr., C.S., 5. Annul Benthic Nutrient Flux Monitoring. ENQUAD Report No. 6-17, Msschusetts Wter Resources Authority, Boston.