research article effects of sewage discharge on trophic ... · is paper provides evidence of the e...

Research ArticleEffects of Sewage Discharge on Trophic State andWater Quality in a Coastal Ecosystem of the Gulf of California

Heacutector Hugo Vargas-Gonzaacutelez1 Joseacute Alfredo Arreola-Lizaacuterraga1

Renato Arturo Mendoza-Salgado2 Liacutea Celina Meacutendez-Rodriacuteguez2

Carlos Hernando Lechuga-Deveze2 Gustavo Padilla-Arredondo1

and Miguel Cordoba-Matson2

1 Centro de Investigaciones Biologicas del Noroeste S C (CIBNOR SC) 85454 Guaymas SON Mexico2 Centro de Investigaciones Biologicas del Noroeste S C (CIBNOR SC) 23090 La Paz BCS Mexico

Correspondence should be addressed to Jose Alfredo Arreola-Lizarraga aarreola04cibnormx

Received 2 November 2013 Accepted 25 November 2013 Published 24 February 2014

Academic Editors M Kumar and K Kuroda

Copyright copy 2014 Hector Hugo Vargas-Gonzalez et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

This paper provides evidence of the effects of urban wastewater discharges on the trophic state and environmental qualityof a coastal water body in a semiarid subtropical region in the Gulf of California The concentrations of dissolved inorganicnutrients and organic matter from urban wastewater primary treatment were estimated La Salada Cove was the receiving waterbody and parameters measured during an annual cycle were temperature salinity dissolved oxygen nitrite nitrate ammoniaorthophosphate and chlorophyll 119886 The effects of sewage inputs were determined by using Trophic State Index (TRIX) and theArid Zone CoastalWater Quality Index (AZCI) It was observed that urban wastewater of the city of Guaymas provided 1237 ton Nyrminus1 and 811 ton P yrminus1 and TRIX indicated that the receiving water body showed symptoms of eutrophication from an oligotrophicstate to a mesotrophic state AZCI also indicated that the environmental quality of the water body was poor The effects of urbanwastewater supply with insufficient treatment resulted in symptoms of eutrophication and loss of ecological functions and servicesof the coastal ecosystem in La Salada Cove

1 Introduction

Mexico has 110 million inhabitants of which sim15 live inthe coastal zone [1] in 156 coastal municipalities locatedalong sim11000 km of coastline [2] and one of the mainenvironmental problems on the national level is that mostcoastal cities are characterized by the insufficient treatmentof municipal wastewater [3] It is estimated that 58 ofthe wastewater from urban centers and 81 of industrialwastes are discharged directly into water bodies with no orinadequate treatment resulting in sim73 of the water bodiesbeing contaminated [4] Industrial ormunicipal sewage is fastemerging as an environmental problemwhereby untreated orpoorly treated water is discharged directly into coastal waterbodies making them highly susceptible to eutrophication

In general it has been observed that tropical coastalecosystems of developing countries have limited treatment

processes of wastewater causing possibly eutrophicationproblems of adjacent coastal systems due to nutrient inputsfrom anthropogenic sources as well as the increased intensityand duration of solar radiation [5 6]

The current state of knowledge of coastal eutrophicationparadigm is changing and evolving from the traditionallimited definition an increase in the rate of supply of organicmatter to an ecosystem [7] Coastal eutrophication shouldnow also include a macroscopic component where it takesinto account the impacts of the drivers of global change andthe increases in world population on the coasts with up to50 of the earthrsquos surface having been converted to agri-cultural and livestock production [8] For this reason itis imperative to increase the studies providing evidence ofchange in coastal ecosystems in order to evaluate the res-ponses to nutrient stimulation [9]

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 618054 7 pageshttpdxdoiorg1011552014618054

2 The Scientific World Journal

Eutrophication is a process that involves an increase inthe trophic status of a water body [7] and therefore the under-standing of changes in the trophic status has been an impor-tant issue that has motivated the design of indexes and mod-els An example of this is the TRIX index (Trrophic Index)[10] and AZCI (Arid Zone Coastal Water Quality Index) [11]The TRIX has been applied mainly in-coastal water bodies ofEurope [12ndash17] The AZCI has been applied in coastal waterbodies in arid regions of Northwest Mexico [11 18]

This study was conducted at La Salada Cove a coastalsubtropical water body in an arid region that receives urbansewage from the city of Guaymas (sim120000 inhab) locatedon the east coast of the Gulf of California The objective is todetermine the effects of nutrient inputs on trophic state andenvironmental quality of the ecosystem

2 Materials and Methods

21 Study Area La Salada Cove is located on the Gulf ofCalifornia in the State of SonoraMexico (27∘521015840N 110∘551015840W)This cove has an area of sim11 ha and a mean depth of 3m itreceives sim80 of the total sewage from the city of Guaymas(sim120000 inhab) and receives a primary treatment (Figure1) La SaladaCove has a seasonal pattern of water temperaturewith maximum of 32∘C in August and minimum of 15∘Cin January salinity varies from 35 to 37 [19] The tide ismixed-semidiurnal with a range of 1m [19]This region has adry desert climate with evaporation of sim3000mmyrminus1 whichexceeds rainfall oflt300mmyrminus1 [20]The seasonal pattern ofwinds is southeastern in summer at 5m sminus1 and northwesterninwinter at 8ndash12m sminus1 and this pattern also influences coastalcirculation [21]

An important consideration is that during the studyperiod in summer there was an extreme event of rain dueto Tropical Storm Jimena in September 3 2009 This eventcollapsed drainage system of the city and urban wastewaterwas discharged directly to Guaymas Bay hence La SaladaCove did not receive wastewater in the summer season andit served as a control period

22 Sampling and Measurements Nutrients and organicmatter loading was estimated by its concentrations observedin the discharge site and the wastewater flow (18600m3 dminus1)to La Salada Cove In the discharge site integrated watersamples were collected in each season for the determinationof nitrite nitrate ammonium orthophosphate biochemicaloxygen demand and chemical oxygen demand Its concen-trations were determined by chemical methods [22]

In La Salada Cove water quality was sampled at 12 sam-pling stations eachweek three times in a representativemonthof each season winter (February) spring (April) summer(September) and fall (November) Water samples were takenbetween 700 and 1300 h At each sampling station waterwas collected both near the surface and near the bottomin 1 L plastic bottles these samples were used to measurenutrients (nitrite nitrate ammonium and orthophosphate)and chlorophyll 119886 Measurements of temperature salinityand dissolved oxygen were made at each station using a

Hydrolab DS5X multisensor Hach Loveland CO USAWater samples were transported on ice to the laboratory foranalysis Nutrient concentration was determined by chemicalmethods [22] Samples for analysis of chlorophyll a werecollected by filtration through Whatman GFC glass fiberfilters extracted with 90 VV acetone and measured byspectrophotometry according to [23]

23 Indexes and Statistical Data Analysis A multivariatemultidimensional scaling on nonparametric transformeddata (log

119909+1

) was applied and standardized to determinewhether seasons had an effect in terms of water quality thestatistical software PRIMER 6 (Primer-E Ivybridge UK) wasused to perform the analysis

The Trophic Index (TRIX) based on the pooled effect ofoxygen saturation nitrite nitrate ammonium orthophos-phate and chlorophyll 119886 was used to assess water bodytrophic state according to [10] The index is given by

TRIX =[log 10 (Chl 119886 sdot DO sdotN sdot P) + 15]

12

(1)

where Chl 119886 is chlorophyll 119886 (120583g L-1) DO is oxygen asan absolute deviation () from saturation N is dissolvedinorganic nitrogen N ndashNO

3

+NO2

+NH4

(120583M) and P is thetotal phosphorus P-PO

4

(120583M) TRIX was scaled from 0 to 10covering a range of four trophic states (0ndash4 high quality andlow trophic level 4-5 goodquality andmoderate trophic level5-6 moderate quality and high trophic level 6ndash10 degradedand very high trophic level)

Also the Arid Zone Coastal Water Quality Index (AZCI)which is based on the combined effects of dissolved oxygennitrite nitrate ammonium and orthophosphate was used toassess water quality [11] The index is given by

AZCI =sum119899

119894=1

119868119894

120577119894

sum119899

119894=1

120577119894

(2)

where 119868119894

120577119894

is the specific environmental index for variable 119894 119899is the number of variables and the range of AZCI is from 0to 1 where a threshold level of 01172 (asymp012) is used to definethe overall environmental quality index Above this level isconsidered to be of good environmental quality while belowthis level is of poor quality

The TRIX and AZCI data grouped by transect for eachseason were analyzed by comparison of means with one-way ANOVA analysis of variance and box and whisker plotresults were obtained For the statistical analysis of the dataStatgraphics Plus 41 was used

3 Results

31 Nutrients and Organic Matter Loads La Salada Covereceives 1237 tonN yrminus1 and 811 ton P yrminus1 from sewage Inaddition values of BODandCODwere 3422 and 2503 kg dminus1respectively (Table 1)

32 Seasonal Hydrologic Patterns The hydrological behaviordata based on temperature salinity dissolved oxygen nitrite

The Scientific World Journal 3

CoveLa Salada

Gulf of California0 1 205

USA

PacificOcean

Gulf of California

Mexico(km)

Guaymasurban area

Guaymas BayNorth

110∘55

998400W 110∘50

998400W

27∘55998400N

27∘51998400N

(a)

Gulf of California

Sampling station n transects

0 21

Primarywastewatertreatment

La SaladaCove

12

3

4

(km)

110∘57998400 110∘5699840030998400998400 110∘56998400

27∘52

998400N

27∘52

99840030

998400998400

27∘53

998400 North

W W W 110∘5599840030998400998400W

NN

(b)

Figure 1 La Salada Cove including urban area from Guaymas city and showing sampling stations and transects

nitrate ammonia orthophosphate and chlorophyll 119886 showedthat between winter and summer environmental conditionswere significantly different while in spring and autumntherewere particular hydrological conditions butwith greatersimilarity to each other (Figure 2) The values of thesevariables are shown in Table 2

33 Environmental Indexes TRIX results indicated that thesummer prevailing state was oligotrophic while in autumnand winter the state mesotrophic was observed In springtransects 1 and 2 closer to the discharge a mesotrophic statewas found while in transects 3 and 4 farther away from thedischarge water quality was oligotrophic (Figure 3(a))

AZCI results indicated better environmental quality inthe summer and worse conditions in the autumn and winterA loss of environmental quality that is poor water qualitywas observed in spring transects 1 and 2 closer to thedischarge while transects 3 and 4 farther from the dischargehad better water quality (Figure 3(b))

4 Discussion

The La Salada Cove urban wastewater receiving primarytreatment is insufficient to reduce inputs of N and P Theevidence of the results in this study suggests that thesenutrient inputs are associated with increasing trophic state


Transform log(X+ 1)NormalizeResemblance D1 Euclidean distance

SeasonSpringFall

WinterSummer

2D stress 021

Figure 2 nMDS ordination of water quality parameters for thestudy area Temperature dissolved oxygen nitrite nitrate ammo-nium ortophosphate and chlorophyll 119886 were included in themultivariate analysis

in the coastal ecosystem and where AZCI and TRIX indexeswere consistent in indicating symptoms of eutrophication

Multivariate analysis (nMDS) showed particular hydro-logical conditions in each season The marked differencesbetween summer and winter are attributed on the one handto the water temperature and phytoplankton biomass and onthe other hand to La Salada Cove summer conditions whereit did not receive nutrient inputs from sewage while in winterit received input nutrients from sewage and specifically phos-phorus concentrations on this season were higher Also thewater temperature was different by sim12∘C between summerand winter and this is a feature typically observed in thisregion of the Gulf of California The temperature differencesis attributed to the influence of the air temperature in this aridregion that has annual oscillations gt14∘C [17] as well as waterbodies of the Gulf region characterized by values of surfacetemperature of 26∘C in summer and 17∘C in winter [24]

The effects of urban wastewater discharges to La SaladaCove were observed in two key variables in addition tobeing indicated by the TRIX and AZCI The responses ofthe body of water to sewage inputs were more evident bythe fact that the summer condition in this study served asthe reference In relation to key variables (1) it was observedin summer that the average chlorophyll 119886 concentrationwas sim6mgmminus3 but the maximum values occurred withblooms that were observed exclusively in the other seasonswhich received loads by sewage and (2) dissolved oxygenconcentrations in summer had average values of sim5mg Lminus1and sim55mg Lminus1 in winter which is substantially lower fromthat observed in winter (sim8mg Lminus1) in this area of theGulf of California without sewage influence [24] The lowervalues of dissolved oxygen concentration are attributed tothe organic load contributed by sewage and indicated byvalues of BOD and COD Dissolved oxygen concentrations

Table 1 Inputs of organic matter and inorganic dissolved nutrientsof La Salada Cove

Variable Load kg dminus1

Biochemical oxygen demand (5 days) 3422Chemical oxygen demand 12503Soluble phosphorus 307Nitrite lt1Nitrate 4Ammonium 375Total dissolved inorganic nitrogen 417

of water ge4mg Lminus1 observed throughout the year both inthe medians and the means suggest that the system hassufficient capacity to assimilate the organic load received butdoes not imply the absence of adverse effects Concentrationsof dissolved oxygen lt3mg Lminus1 were observed in autumnand winter indicating hypoxic events and this represents animpact to the environment and aquatic life

The TRIX indicated that in summer when there were nosewage inputs the systemwas oligotrophic while in the otherseasons mesotrophic conditions were observed and this isattributed to nutrient inputs from sewage increasing the rateof supply organic material causing eutrophication symptomsThe TRIX in general has been well accepted for applicationin environmental management actions [25] even establishedin the Italian environmental legislation [26] the results of thisstudy suggest that the TRIX can be applicable for monitoringand trophic state evaluation in coastal water bodies of theGulf of California In this study it was notable that in autumnand winter the spatial influence of wastewater dischargescovered all the system but in spring the influence was in thefirst two sampling transects nearest to discharges which hadsignificant differences to transects that are more distant Thisvariability is associated with the load of nutrients and organicmatter and coastal hydrodynamic conditions prevailing ineach season [19ndash21] considering that La Salada Cove is anopen system influenced by seasonal wind patterns that occursin the Gulf and induces waves [21] coastal circulation aswell as tidal mixing [19] which are processes that favor thedilution and assimilation of nutrients and organic matter andgenerally contribute to this body of water which is less sus-ceptible to eutrophication This is consistent with observa-tions [27 28] in the sense that the magnitude of the adverseeffects of sewage sources and depends on the magnitudeof the discharges of nitrogen and phosphorus as well aspotential dilution and assimilative capacity of each coastalwater body

The AZCI indicated the same pattern as the TRIX on theeffects of wastewater discharges in La Salada Cove showinga poor environmental quality as the median of the datasampling transects is below the alert threshold (015) inseasons that the body of water sewage inputs was receivedand it was also notable that the first two transects closest tothe discharge area had the worst environmental quality Pre-vious studies showed that AZCI also worked to characterizeseasonal changes by environmental effects (rain and coastal


Table2Va

lues

oftemperaturesalinitydiss

olvedoxygenn

itriten

itrateam

mon

iumortho

phosph

ateandchloroph

yll119886

arou

ndyear

inLa

Salada

Cove

Sprin

gSummer

Fall

Winter

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

Temperature

(∘ C)274plusmn05

281272minus297293plusmn08



169144minus189

DO(m

gLminus1

)43plusmn07

42

34minus67

56plusmn03

56

47minus61

58plusmn17

56

25minus8

55plusmn16

58

17minus81

N-N

O2

minus

(120583M)0218plusmn047


1277035minus9110511plusmn038

0378003minus1460661plusmn037

0521001minus132

N-N

O3

(120583M)0145plusmn017


006


0377003minus0820517plusmn023

0456006minus094

N-N

H4

(120583M)582plusmn683

1979023minus19311733plusmn26

0806005minus16224371plusmn613

1197001minus19091609plusmn121

1238009minus399

PO4

(120583M)

4291plusmn638

1231034minus21981495plusmn055


1354032minus16425014plusmn303

2184138minus2198

Chla

(mgmminus3

)09plusmn18

04

0minus137

57plusmn07

56

34minus67

25plusmn56

08

0minus372

22plusmn29

10minus169


Eutrophic

Mesotrophic

Oligotrophic

Spring Summer Autumn Winter1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

TRIX

Inde

x

6

5

4

3

2

1

0

(a)

015 alert threshold


AZC

I Ind

ex

04

03

02

01

0

(b)

Figure 3 Box and whisker plot of the (a) TRIX and (b) AZCI for La Salada Cove during seasons Numbers 1 to 4 represent the transectsMedian quartiles ranges and outliers of data are shown for each event It shows levels of trophic state and water quality influences fromurban sewage inputs

processes) [11] and anthropogenic influences [18] in coastallagoons from the Gulf of California

AZCI andTRIX indices differ primarily in that (1) the firstincorporates chlorophyll 119886 a biological variable expressingphytoplankton biomass and (2) the second used algebraicfunction involving different scale and interpretation inaddition to the fact that AZCI applicates standardizationprocess of the inverses values of the variables and the lowestconcentration is the weight value which is more importantIn particular the average chlorophyll 119886 value was lt25relatively low for seasons where therewere sewage inputs buteventually had extreme values that might make a differencebetween TRIX and AZCI In practical terms the two waterindices provided similar results and were consistent with theenvironmental condition of La Salada Cove Taking this intoconsideration priority should be given to the development ofreliable indicators of trophic levels of coastal ecosystems alsoit would be useful to identify policies aimed at establishingenvironmental legislation in order to help abate the causes ofthe process of eutrophication [29]

This study provides evidence of the process of eutrophi-cation in the coastal ecosystem of La Salada Cove this infor-mation is useful since it is necessary to increase the amount ofdata of many coastal water bodies in Mexico [30] in order tocompare coastal scenarios in other parts of the world in orderto achieve a better understanding of the eutrophication pro-cesses [31] The challenge is to establish a strategy to reducenutrient inputs from urban wastewater in order to maintainand prevent the loss of ecosystem services provided bycoastal ecosystems In particular to explore cases where thecost benefit of control measures of excessive nutrient loadingis considered and evaluated there are limited case studies a

good example is the recent work done in the Gulf of Finland[32]

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

Refugio Lopez and Andres Hernandez of CIBNOR pro-vided technical support during sampling and provided wateranalysis David Urıas prepared the map Comision Nacionaldel Agua (CONAGUA) and Consejo Nacional de Cienciay Tecnologıa (CONACYT) provided funding to this studyby research project CONAGUA-CONACYT-2007-01-66573Hector Hugo Vargas-Gonzalez would also like to thankCONACYT for the grant that has allowed him to pursue hismaster studies

References

[1] INEGI ldquoAspectos Geograficosrdquo Instituto Nacional de GeografıaEstadıstica e Informatica Mexico 2010

[2] CIMARES ldquoPolıtica Nacional de Mares y Costas de MexicoGestion Integral de las Regiones mas Dinamicas del TerritorioNacionalrdquo Comision Intersecretarial para elManejo Sustentablede Mares y Costas Secretarıa de Medio Ambiente y RecursosNaturales Mexico 2012

[3] CONABIO ldquoCapital Natural y bienestar socialrdquo ComisionNacional para el Conocimiento y Uso de la BiodiversidadMexico 2006


[4] CONAGUA ldquoEstadısticas del Agua en Mexico edicion 2011rdquoComision Nacional del Agua SEMARNAT-CONAGUAMexico 2011

[5] J E Corredor R W Howarth R R Twilley and J M MorellldquoNitrogen cycling and anthropogenic impact in the tropicalinteramerican seasrdquo Biogeochemistry vol 46 no 1ndash3 pp 163ndash178 1999

[6] J A Downing M McClain R Twilley et al ldquoThe impactof accelerating land-use change on the N-cycle of tropicalaquatic ecosystems current conditions and projected changesrdquoBiogeochemistry vol 46 no 1ndash3 pp 109ndash148 1999

[7] SWNixon ldquoCoastalmarine eutrophication a definition socialcauses and future concernsrdquoOphelia vol 41 pp 199ndash229 1995

[8] S W Nixon ldquoEutrophication and the macroscoperdquoHydrobiolo-gia vol 629 no 1 pp 5ndash19 2009

[9] J E Cloern ldquoOur evolving conceptual model of the coastaleutrophication problemrdquo Marine Ecology Progress Series vol210 pp 223ndash253 2001

[10] R AVollenweider F Giovanardi GMontanari andA RinaldildquoCharacterization of the trophic conditions of marine coastalwaters with special reference to the NW Adriatic Sea proposalfor a Trophic Scale Turbidity and generalized Water QualityIndexrdquo Envirometrics vol 9 pp 329ndash357 1998

[11] R A Mendoza-Salgado C H Lechuga-Deveze and A Ortega-Rubio ldquoFirst approach of a method to assess water quality forarid climate bay in the Gulf of Californiardquo Science of the TotalEnvironment vol 347 no 1ndash3 pp 208ndash216 2005

[12] S Moncheva V Dontcheva G Shtereva L Kamburska AMalej and S Gorinstein ldquoApplication of eutrophication indicesfor assessment of the Bulgarian Black Sea coastal ecosystemecological qualityrdquo Water Science and Technology vol 46 no8 pp 19ndash28 2002

[13] F Giovanardi and R A Vollenweider ldquoTrophic conditions ofmarine coastal waters experience in applying the Trophic IndexTRIX to two areas of the Adriatic and Tyrrhenian seasrdquo Journalof Limnology vol 63 no 2 pp 199ndash218 2004

[14] M Pettine B Casentini S Fazi F Giovanardi and R PagnottaldquoA revisitation of TRIX for trophic status assessment in thelight of the European Water Framework Directive applicationto Italian coastal watersrdquoMarine Pollution Bulletin vol 54 no9 pp 1413ndash1426 2007

[15] F Salas H Teixeira C Marcos J C Marques and A Perez-Ruzafa ldquoApplicability of the trophic index TRIX in two tran-sitional ecosystems The Mar Menor lagoon (Spain) and theMondego estuary (Portugal)rdquo ICES Journal of Marine Sciencevol 65 no 8 pp 1442ndash1448 2008

[16] I Primpas andM Karydis ldquoScaling the trophic index (TRIX) inoligotrophic marine environmentsrdquo Environmental Monitoringand Assessment vol 178 no 1ndash4 pp 257ndash269 2011

[17] N Balkis B Toklu-Alici andM Balci ldquoEvaluation of Ecologicalquality Status with the Trophic Index (TRIX) values in thecoastal waters of the Gulfs of Erdek and Bandirma In theMarmara Seardquo in EcologicalWater QualityWater Treatment andReuse K Voudouris Ed pp 1ndash22 InTech 2012

[18] L Morquecho R Alonso-Rodrıguez J A Arreola-Lizarragaand A Reyes-Salinas ldquoFactors associated with moderateblooms of Pyrodinium bahamense in shallow and restrictedsubtropical lagoons in the Gulf of Californiardquo Botanica Marinavol 55 pp 611ndash623 2012

[19] M F Lavin and S G Marinone ldquoAn overview of the physicaloceanography of the Gulf of Californiardquo in Nonlinear Pro-cesses in Geophysical Fluid Dynamics O U Velasco-Fuentes J

Sheinbaum and J Ochoa Eds pp 173ndash204 Kluwer AcademicPublishers 2003

[20] E GarcıaModificaciones al sistema de clasificacion climatica deKoppen (para adaptarlo a las condiciones climaticas de Mexico)Instituto de Geografıa UNAM Mexico DF 5th edition 2004

[21] A Pares-Sierra AMascarenhas S GMarinone and R CastroldquoTemporal and spatial variation of the surface winds in the Gulfof Californiardquo Geophysical Research Letters vol 30 no 6 pp1ndash4 2003

[22] J D H Strickland and T R Parsons A Practical Handbook ofSeawater Analysis Fisheries Research Board of Canada Bulletin2nd edition 1972

[23] T R Parsons Y Maita and CM LalliAManual Chemical andBiological Methods for Seawater Analysis Pergamon Press NewYork NY USA 1984

[24] S Alvarez-Borrego and J R Lara-Lara ldquoThe physical environ-ment and primary productivity of the Gulf of Californiardquo inTheGulf of California and Peninsular Province of the Californias JP Dauphin and B R Simoneit Eds Memoir 47 pp 555ndash567American Association of Petroleum Geologists Tulsa OklaUSA 1991

[25] M Vascetta P Kauppila and E Furman ldquoAggregate indicatorsin coastal policy making potentials of the trophic index TRIXfor sustainable considerations of eutrophicationrdquo SustainableDevelopment vol 16 no 4 pp 282ndash289 2008

[26] G Casazza C Silvestri and E Spada ldquoClassification of coastalwaters according to the new Italian water legislation andcomparison with the European Water Directiverdquo Journal ofCoastal Conservation vol 9 no 1 pp 65ndash72 2003

[27] S J Painting M J Devlin S J Malcolm et al ldquoAssessing theimpact of nutrient enrichment in estuaries susceptibility toeutrophicationrdquo Marine Pollution Bulletin vol 55 no 1ndash6 pp74ndash90 2007

[28] D Scavia and Y Liu ldquoExploring estuarine nutrient susceptibil-ityrdquo Environmental Science and Technology vol 43 no 10 pp3474ndash3479 2009

[29] C M Duarte ldquoCoastal eutrophication research a new aware-nessrdquo Hydrobiologia vol 629 no 1 pp 263ndash269 2009

[30] J R Lara-Lara J A Arreola-Lizarraga and L E Calderon-Aguilera ldquoLos ecosistemas costeros insulares y epicontinen-talesrdquo in Capital Natural de Mexico vol 1 Conocimiento Actualde la Biodiversidad CONABIO Ed pp 109ndash134 Mexico 2008

[31] J H Andersen and D J Conley ldquoEutrophication in coastalmarine ecosystems towards better understanding andmanage-ment strategiesrdquo Hydrobiologia vol 629 no 1 pp 1ndash4 2009

[32] K Hyytiainen and A Huhtala ldquoCombating eutrophication incoastal areas at risk for oil spillsrdquoAnnals of Operations Researchvol 191 pp 63ndash274 2011

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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International Journal of


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Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


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Applied ChemistryJournal of



Theoretical ChemistryJournal of


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Spectroscopy

Analytical ChemistryInternational Journal of


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Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


Eutrophication is a process that involves an increase inthe trophic status of a water body [7] and therefore the under-standing of changes in the trophic status has been an impor-tant issue that has motivated the design of indexes and mod-els An example of this is the TRIX index (Trrophic Index)[10] and AZCI (Arid Zone Coastal Water Quality Index) [11]The TRIX has been applied mainly in-coastal water bodies ofEurope [12ndash17] The AZCI has been applied in coastal waterbodies in arid regions of Northwest Mexico [11 18]

This study was conducted at La Salada Cove a coastalsubtropical water body in an arid region that receives urbansewage from the city of Guaymas (sim120000 inhab) locatedon the east coast of the Gulf of California The objective is todetermine the effects of nutrient inputs on trophic state andenvironmental quality of the ecosystem

2 Materials and Methods

21 Study Area La Salada Cove is located on the Gulf ofCalifornia in the State of SonoraMexico (27∘521015840N 110∘551015840W)This cove has an area of sim11 ha and a mean depth of 3m itreceives sim80 of the total sewage from the city of Guaymas(sim120000 inhab) and receives a primary treatment (Figure1) La SaladaCove has a seasonal pattern of water temperaturewith maximum of 32∘C in August and minimum of 15∘Cin January salinity varies from 35 to 37 [19] The tide ismixed-semidiurnal with a range of 1m [19]This region has adry desert climate with evaporation of sim3000mmyrminus1 whichexceeds rainfall oflt300mmyrminus1 [20]The seasonal pattern ofwinds is southeastern in summer at 5m sminus1 and northwesterninwinter at 8ndash12m sminus1 and this pattern also influences coastalcirculation [21]

An important consideration is that during the studyperiod in summer there was an extreme event of rain dueto Tropical Storm Jimena in September 3 2009 This eventcollapsed drainage system of the city and urban wastewaterwas discharged directly to Guaymas Bay hence La SaladaCove did not receive wastewater in the summer season andit served as a control period

22 Sampling and Measurements Nutrients and organicmatter loading was estimated by its concentrations observedin the discharge site and the wastewater flow (18600m3 dminus1)to La Salada Cove In the discharge site integrated watersamples were collected in each season for the determinationof nitrite nitrate ammonium orthophosphate biochemicaloxygen demand and chemical oxygen demand Its concen-trations were determined by chemical methods [22]

In La Salada Cove water quality was sampled at 12 sam-pling stations eachweek three times in a representativemonthof each season winter (February) spring (April) summer(September) and fall (November) Water samples were takenbetween 700 and 1300 h At each sampling station waterwas collected both near the surface and near the bottomin 1 L plastic bottles these samples were used to measurenutrients (nitrite nitrate ammonium and orthophosphate)and chlorophyll 119886 Measurements of temperature salinityand dissolved oxygen were made at each station using a

Hydrolab DS5X multisensor Hach Loveland CO USAWater samples were transported on ice to the laboratory foranalysis Nutrient concentration was determined by chemicalmethods [22] Samples for analysis of chlorophyll a werecollected by filtration through Whatman GFC glass fiberfilters extracted with 90 VV acetone and measured byspectrophotometry according to [23]

23 Indexes and Statistical Data Analysis A multivariatemultidimensional scaling on nonparametric transformeddata (log

119909+1

) was applied and standardized to determinewhether seasons had an effect in terms of water quality thestatistical software PRIMER 6 (Primer-E Ivybridge UK) wasused to perform the analysis

The Trophic Index (TRIX) based on the pooled effect ofoxygen saturation nitrite nitrate ammonium orthophos-phate and chlorophyll 119886 was used to assess water bodytrophic state according to [10] The index is given by

TRIX =[log 10 (Chl 119886 sdot DO sdotN sdot P) + 15]

12

(1)

where Chl 119886 is chlorophyll 119886 (120583g L-1) DO is oxygen asan absolute deviation () from saturation N is dissolvedinorganic nitrogen N ndashNO

3

+NO2

+NH4

(120583M) and P is thetotal phosphorus P-PO

4

(120583M) TRIX was scaled from 0 to 10covering a range of four trophic states (0ndash4 high quality andlow trophic level 4-5 goodquality andmoderate trophic level5-6 moderate quality and high trophic level 6ndash10 degradedand very high trophic level)

Also the Arid Zone Coastal Water Quality Index (AZCI)which is based on the combined effects of dissolved oxygennitrite nitrate ammonium and orthophosphate was used toassess water quality [11] The index is given by

AZCI =sum119899

119894=1

119868119894

120577119894

sum119899

119894=1

120577119894

(2)

where 119868119894

120577119894

is the specific environmental index for variable 119894 119899is the number of variables and the range of AZCI is from 0to 1 where a threshold level of 01172 (asymp012) is used to definethe overall environmental quality index Above this level isconsidered to be of good environmental quality while belowthis level is of poor quality

The TRIX and AZCI data grouped by transect for eachseason were analyzed by comparison of means with one-way ANOVA analysis of variance and box and whisker plotresults were obtained For the statistical analysis of the dataStatgraphics Plus 41 was used

3 Results

31 Nutrients and Organic Matter Loads La Salada Covereceives 1237 tonN yrminus1 and 811 ton P yrminus1 from sewage Inaddition values of BODandCODwere 3422 and 2503 kg dminus1respectively (Table 1)

32 Seasonal Hydrologic Patterns The hydrological behaviordata based on temperature salinity dissolved oxygen nitrite


CoveLa Salada


USA

PacificOcean

Gulf of California

Mexico(km)

Guaymasurban area

Guaymas BayNorth

110∘55

998400W 110∘50

998400W

27∘55998400N

27∘51998400N

(a)

Gulf of California


0 21


La SaladaCove

12

3

4

(km)

110∘57998400 110∘5699840030998400998400 110∘56998400

27∘52

998400N

27∘52

99840030

998400998400

27∘53

998400 North

W W W 110∘5599840030998400998400W

NN

(b)





4 Discussion




SeasonSpringFall

WinterSummer

2D stress 021












Table2Va

lues


olvedoxygenn

itriten

itrateam

mon

iumortho

phosph

ateandchloroph

yll119886

arou

ndyear

inLa

Salada

Cove

Sprin

gSummer

Fall

Winter

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

Temperature

(∘ C)274plusmn05




169144minus189

DO(m

gLminus1

)43plusmn07

42

34minus67

56plusmn03

56

47minus61

58plusmn17

56

25minus8

55plusmn16

58

17minus81

N-N

O2

minus

(120583M)0218plusmn047


1277035minus9110511plusmn038

0378003minus1460661plusmn037

0521001minus132

N-N

O3

(120583M)0145plusmn017


006


0377003minus0820517plusmn023

0456006minus094

N-N

H4

(120583M)582plusmn683

1979023minus19311733plusmn26

0806005minus16224371plusmn613

1197001minus19091609plusmn121

1238009minus399

PO4

(120583M)

4291plusmn638

1231034minus21981495plusmn055


1354032minus16425014plusmn303

2184138minus2198

Chla

(mgmminus3

)09plusmn18

04

0minus137

57plusmn07

56

34minus67

25plusmn56

08

0minus372

22plusmn29

10minus169


Eutrophic

Mesotrophic

Oligotrophic


TRIX

Inde

x

6

5

4

3

2

1

0

(a)

015 alert threshold


AZC

I Ind

ex

04

03

02

01

0

(b)








Acknowledgments


References












































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


CoveLa Salada


USA

PacificOcean

Gulf of California

Mexico(km)

Guaymasurban area

Guaymas BayNorth

110∘55

998400W 110∘50

998400W

27∘55998400N

27∘51998400N

(a)

Gulf of California


0 21


La SaladaCove

12

3

4

(km)

110∘57998400 110∘5699840030998400998400 110∘56998400

27∘52

998400N

27∘52

99840030

998400998400

27∘53

998400 North

W W W 110∘5599840030998400998400W

NN

(b)





4 Discussion




SeasonSpringFall

WinterSummer

2D stress 021












Table2Va

lues


olvedoxygenn

itriten

itrateam

mon

iumortho

phosph

ateandchloroph

yll119886

arou

ndyear

inLa

Salada

Cove

Sprin

gSummer

Fall

Winter

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

Temperature

(∘ C)274plusmn05




169144minus189

DO(m

gLminus1

)43plusmn07

42

34minus67

56plusmn03

56

47minus61

58plusmn17

56

25minus8

55plusmn16

58

17minus81

N-N

O2

minus

(120583M)0218plusmn047


1277035minus9110511plusmn038

0378003minus1460661plusmn037

0521001minus132

N-N

O3

(120583M)0145plusmn017


006


0377003minus0820517plusmn023

0456006minus094

N-N

H4

(120583M)582plusmn683

1979023minus19311733plusmn26

0806005minus16224371plusmn613

1197001minus19091609plusmn121

1238009minus399

PO4

(120583M)

4291plusmn638

1231034minus21981495plusmn055


1354032minus16425014plusmn303

2184138minus2198

Chla

(mgmminus3

)09plusmn18

04

0minus137

57plusmn07

56

34minus67

25plusmn56

08

0minus372

22plusmn29

10minus169


Eutrophic

Mesotrophic

Oligotrophic


TRIX

Inde

x

6

5

4

3

2

1

0

(a)

015 alert threshold


AZC

I Ind

ex

04

03

02

01

0

(b)








Acknowledgments


References












































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



SeasonSpringFall

WinterSummer

2D stress 021












Table2Va

lues


olvedoxygenn

itriten

itrateam

mon

iumortho

phosph

ateandchloroph

yll119886

arou

ndyear

inLa

Salada

Cove

Sprin

gSummer

Fall

Winter

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

Temperature

(∘ C)274plusmn05




169144minus189

DO(m

gLminus1

)43plusmn07

42

34minus67

56plusmn03

56

47minus61

58plusmn17

56

25minus8

55plusmn16

58

17minus81

N-N

O2

minus

(120583M)0218plusmn047


1277035minus9110511plusmn038

0378003minus1460661plusmn037

0521001minus132

N-N

O3

(120583M)0145plusmn017


006


0377003minus0820517plusmn023

0456006minus094

N-N

H4

(120583M)582plusmn683

1979023minus19311733plusmn26

0806005minus16224371plusmn613

1197001minus19091609plusmn121

1238009minus399

PO4

(120583M)

4291plusmn638

1231034minus21981495plusmn055


1354032minus16425014plusmn303

2184138minus2198

Chla

(mgmminus3

)09plusmn18

04

0minus137

57plusmn07

56

34minus67

25plusmn56

08

0minus372

22plusmn29

10minus169


Eutrophic

Mesotrophic

Oligotrophic


TRIX

Inde

x

6

5

4

3

2

1

0

(a)

015 alert threshold


AZC

I Ind

ex

04

03

02

01

0

(b)








Acknowledgments


References












































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Table2Va

lues


olvedoxygenn

itriten

itrateam

mon

iumortho

phosph

ateandchloroph

yll119886

arou

ndyear

inLa

Salada

Cove

Sprin

gSummer

Fall

Winter

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

MeanplusmnSD

Median

Minminus

Max

Temperature

(∘ C)274plusmn05




169144minus189

DO(m

gLminus1

)43plusmn07

42

34minus67

56plusmn03

56

47minus61

58plusmn17

56

25minus8

55plusmn16

58

17minus81

N-N

O2

minus

(120583M)0218plusmn047


1277035minus9110511plusmn038

0378003minus1460661plusmn037

0521001minus132

N-N

O3

(120583M)0145plusmn017


006


0377003minus0820517plusmn023

0456006minus094

N-N

H4

(120583M)582plusmn683

1979023minus19311733plusmn26

0806005minus16224371plusmn613

1197001minus19091609plusmn121

1238009minus399

PO4

(120583M)

4291plusmn638

1231034minus21981495plusmn055


1354032minus16425014plusmn303

2184138minus2198

Chla

(mgmminus3

)09plusmn18

04

0minus137

57plusmn07

56

34minus67

25plusmn56

08

0minus372

22plusmn29

10minus169


Eutrophic

Mesotrophic

Oligotrophic


TRIX

Inde

x

6

5

4

3

2

1

0

(a)

015 alert threshold


AZC

I Ind

ex

04

03

02

01

0

(b)








Acknowledgments


References












































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Eutrophic

Mesotrophic

Oligotrophic


TRIX

Inde

x

6

5

4

3

2

1

0

(a)

015 alert threshold


AZC

I Ind

ex

04

03

02

01

0

(b)








Acknowledgments


References












































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

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