Potential for using high frequency turbidity as a proxy for total phosphorus in Sävjaån
Transport of particles carrying nutrients and contaminants from land to sea is a challenge to monitor due to the high temporal variability in concentrations. Phosphorus is a particle associated nutrient, largely affecting the state of waters due to its effects on eutrophication. When using tradition...
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| Format: | H2 |
| Language: | Inglés Swedish |
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SLU/Dept. of Aquatic Sciences and Assessment
2016
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| _version_ | 1855571526850445312 |
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| author | Lannergård, Emma |
| author_browse | Lannergård, Emma |
| author_facet | Lannergård, Emma |
| author_sort | Lannergård, Emma |
| collection | Epsilon Archive for Student Projects |
| description | Transport of particles carrying nutrients and contaminants from land to sea is a challenge to monitor due to the high temporal variability in concentrations. Phosphorus is a particle associated nutrient, largely affecting the state of waters due to its effects on eutrophication. When using traditional monitoring methods, there is a prevailing risk of misjudging the state of water and transport of phosphorus due to lack of data. Therefore, this study aimed to evaluate the potential use of continuous high frequency turbidity as a proxy for total phosphorus concentration. An in situ sensor monitoring turbidity every 10th minute was deployed from 2012-2015 in Sävjaån, a river draining a mixed land use catchment in central Sweden. The sub-catchment is an agricultural area dominated by clay soil close to Uppsala in Sweden. The results from measuring high frequency turbidity with the sensor were compared to traditional monthly grab sampling. A significant information loss could be observed when performing grab sampling, the turbidity from the sensor varied more and showed higher maximum values (9-15 times). The correlation between the different parameters was evaluated by linear regression. The results show very high correlation between turbidity and total phosphorus (r2= 0.79) and high correlation between turbidity and total suspended solids (r2= 0.67). The relationships seemed to be affected by calibration of the sensor, spatial variation and the proportion of phosphate and total phosphorus in Sävjaån. The phosphorus load was calculated from the high frequency data and compared to linear interpolation and piecewise constant interpolation of grab samples. Loads calculated from high frequency data was during two years (2012 and 2015) 31% and 17% larger than when using linear interpolation. However, the timing and the instant flow at the time of grab sampling had large impact on the estimated load when using linear interpolation (2013 and 2014). It could be concluded that most P was transported when high discharge and high concentrations coincided. When comparing the calculations of ecological quality ratios from grab sampling and high frequency data the difference was modest. |
| format | H2 |
| id | RepoSLU9475 |
| institution | Swedish University of Agricultural Sciences |
| language | Inglés swe |
| publishDate | 2016 |
| publishDateSort | 2016 |
| publisher | SLU/Dept. of Aquatic Sciences and Assessment |
| publisherStr | SLU/Dept. of Aquatic Sciences and Assessment |
| record_format | eprints |
| spelling | RepoSLU94752016-09-08T14:18:10Z Potential for using high frequency turbidity as a proxy for total phosphorus in Sävjaån Lannergård, Emma surface water quality high frequency monitoring continuous monitoring turbidity in situ sensor surrogate measurements total suspended solids total phosphorus phosphorus phosphorus load load estimation Transport of particles carrying nutrients and contaminants from land to sea is a challenge to monitor due to the high temporal variability in concentrations. Phosphorus is a particle associated nutrient, largely affecting the state of waters due to its effects on eutrophication. When using traditional monitoring methods, there is a prevailing risk of misjudging the state of water and transport of phosphorus due to lack of data. Therefore, this study aimed to evaluate the potential use of continuous high frequency turbidity as a proxy for total phosphorus concentration. An in situ sensor monitoring turbidity every 10th minute was deployed from 2012-2015 in Sävjaån, a river draining a mixed land use catchment in central Sweden. The sub-catchment is an agricultural area dominated by clay soil close to Uppsala in Sweden. The results from measuring high frequency turbidity with the sensor were compared to traditional monthly grab sampling. A significant information loss could be observed when performing grab sampling, the turbidity from the sensor varied more and showed higher maximum values (9-15 times). The correlation between the different parameters was evaluated by linear regression. The results show very high correlation between turbidity and total phosphorus (r2= 0.79) and high correlation between turbidity and total suspended solids (r2= 0.67). The relationships seemed to be affected by calibration of the sensor, spatial variation and the proportion of phosphate and total phosphorus in Sävjaån. The phosphorus load was calculated from the high frequency data and compared to linear interpolation and piecewise constant interpolation of grab samples. Loads calculated from high frequency data was during two years (2012 and 2015) 31% and 17% larger than when using linear interpolation. However, the timing and the instant flow at the time of grab sampling had large impact on the estimated load when using linear interpolation (2013 and 2014). It could be concluded that most P was transported when high discharge and high concentrations coincided. When comparing the calculations of ecological quality ratios from grab sampling and high frequency data the difference was modest. Kontinuerligt rapporteras det i svenska medier om algblomning och övergödning i ytvatten och i Östersjön. Ökat antal algplankton och bakterier skapar en grön och grynig vattenmassa. Det leder även till potentiell syrebrist i vattnet och störda ekosystem. Ur ett historiskt perspektiv har mängden näringsämnen som transporteras till Östersjön ökat. Idag är det främst jordbruk, vattenreningsverk, industrier, privata avlopp och dagvatten som bidrar till problemet. Fosfor är ett av näringsämnena som till stor del påverkar övergödningsproblematiken. För att kunna hantera övergödningsproblematiken behöver vi veta hur det är ställt i svenska sjöar och vattendrag. Vanligtvis tas månatliga vattenprover som analyseras i ett laboratorium, tiden mellan vattenproverna estimeras med hjälp av olika metoder. Fosforhalten i vattnet varierar dock avsevärt i tid och rum. På grund av det är den årliga transporten fosfor från ett vattendrag svår att uppskatta på ett trovärdigt sätt. I den här studien har en ny metod för att beskriva förhållandena i Sävjaån testats och utvärderats. En sensor som mäter grumlighet i vatten (turbiditet) var 10:e minut har monterats i Sävjaån i närheten av Uppsala under perioden 2012-2015. Fosfor transporteras ofta tillsammans med partiklar och dessa bidrar till grumlighet i vattnet. Därför har möjligheten att använda turbiditet som ett substitut för fosformätningar undersökts. Det visade sig finnas ett väldigt starkt samband mellan turbiditet och fosfor i Sävjaån. Ett starkt samband kunde även observeras mellan turbiditet och mängd vattenburna partiklar (suspenderat material/slamhalt). När förhållandena i vattnet övervakades med hjälp av sensorn var det tydligt att mycket information saknades när endast månatliga vattenprover togs. När de två metoderna jämfördes varierade grumligheten mer och 9-15 gånger högre maximala värden uppmättes. Den totala mängden transporterat fosfor per år visade sig vara 31% and 17% (2012 och 2015) större när den beräknades med hjälp av informationen från sensorn i jämförelse med den vanligen använda metoden. När höga vattenflöden inträffade samtidigt med höga fosforkoncentrationer transporterades störst mängd fosfor. Även om det innebär en osäkerhet att använda grumlighet som ett mått för fosfor finns stora möjligheter till bättre uppskattningar av fosfortransport. Med en välskött sensor och noggrant kontrollerad data finns potential för mer representativa resultat som kan hjälpa samhället att hantera övergödningsproblematiken på ett bättre sätt. SLU/Dept. of Aquatic Sciences and Assessment 2016 H2 eng swe https://stud.epsilon.slu.se/9475/ |
| spellingShingle | surface water quality high frequency monitoring continuous monitoring turbidity in situ sensor surrogate measurements total suspended solids total phosphorus phosphorus phosphorus load load estimation Lannergård, Emma Potential for using high frequency turbidity as a proxy for total phosphorus in Sävjaån |
| title | Potential for using high frequency turbidity as a proxy for total phosphorus in Sävjaån |
| title_full | Potential for using high frequency turbidity as a proxy for total phosphorus in Sävjaån |
| title_fullStr | Potential for using high frequency turbidity as a proxy for total phosphorus in Sävjaån |
| title_full_unstemmed | Potential for using high frequency turbidity as a proxy for total phosphorus in Sävjaån |
| title_short | Potential for using high frequency turbidity as a proxy for total phosphorus in Sävjaån |
| title_sort | potential for using high frequency turbidity as a proxy for total phosphorus in sävjaån |
| topic | surface water quality high frequency monitoring continuous monitoring turbidity in situ sensor surrogate measurements total suspended solids total phosphorus phosphorus phosphorus load load estimation |