Calculation and temporal variability of ventilation coefficient depending on location and characteristics of houses in Balikesir city center

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2257

ANALYSIS OF ENVIRONMENTAL EFFECTS ON A SHIP

POWER PLANT INTEGRATED WITH WASTE HEAT

RECOVERY SYSTEM

Cengiz Deniz, Yalcin Durmusoglu1

1_{Istanbul Technical University, Maritime Faculty, Department of Marine Engineering, 34940 Tuzla-Istanbul, Turkey.}

ABSTRACT

Waste heat recovery has attracted attention throughout the world because of the greenhouse effect by fossil fuels, their depletion, and safety of energy demand. It is also considered as a free source of energy requirements. For this purpose, various methods have been developed and implemented in order to recover energy from waste heat in industrial power plants in recent years. Marine power plants use fossil fuels to meet a major amount of their energy requirements. Therefore, this leads to not only increase energy production costs and environmental pollution but also decrease ship energy efficiency. Therefore, environmental friendly methods need to be preferred by increasing the ship energy efficiency and decreasing energy production costs. In this study, waste heat recovery methods have been investigated and their effects on ship energy efficiency and environmental pollution have been analyzed. A novel concept has been definite which is called specific emissions ratio (SER) for a waste heat recovery system. SER can be indicated a decreasing of emissions rate of a waste heat recovery plants. It is shown in the results that the value of SER for CO2 gas component is 3.51 t(kW year)-1_{in the application without waste heat} recovery whereas the same value goes down to 3.29 t(kW year)-1 _{with the application of waste heat} recovery. This system leads to the saving of 0.22 tons of fuel per unit kW power.

KEYWORDS:

Air pollution, Environment effect, Marine power plant, Ship energy efficiency, Waste heat recovery.

INTRODUCTION

Today, almost 90% of the world goods are carried by maritime transport account for over 90% of European Union external trade and 43% of its internal trade due to the marine transportation sector is one of the major causes of air pollution [1]. Emissions from ships affect global air quality,

SHRSOH¶V KHDOWK WKH PDULQH HFRORJ\ DQG JOREDO warming. Carbon dioxides (CO2), carbon monoxide (CO), particulate matter (PM), nitrogen oxides (NOx), and sulfur oxides (SOx) are the most significant pollutants emitted from marine diesel engines. Ships emit a range of gases from their operations at sea and in port areas. The emissions produced by navigation result from the combustion of fuel in internal combustion engines.

Annex VI of the MARPOL convention, adopted by International Maritime Organization (IMO) in 1997, sets limits on NOx and SOx emissions from ship exhaust gases for the prevention of air pollution from ships. The IMO has also specified Energy Efficiency Design Index (EEDI) and Ship Energy Efficiency Management Plan (SEEMP) that will reduce greenhouse gas emission. In the sixty second and sixty third meetings held by Marine Environment Protection Committee (MEPC), IMO started Energy Efficiency Design Index (EEDI) application in order to reach greenhouse gas emission targets identified by MARPOL Regulation Annex VI for ships navigating on international waters [2]. EEDI, is an index which is calculated for every ship and indication of the energy efficiency of the ship in question. This index has to be below the limits required by IMO. EEDI is the amount of CO2 emitted per mile and per load to the atmosphere by the ships (g CO2/ dwt. nm). With the implementation of EEDI, ship operators should take a series of technical measures in order to reduce their CO2 emissions. The proposed or feasible technical measures on CO2 reduction mainly is aimed to improving energy efficiency of ships. Ship energy efficiency can be improved by utilizing waste heat recovery (WHR) systems.

Waste heat recovery means providing more energy production by the regular fuel consumption [3]. In other words, it leads to energy production efficiency. WHR systems are also environmental friendly implementations. While there is an increase in energy recovery, additional fuel consumption is not required. In this way, more fuel is saved. There will be a decrease in harmful exhaust gas emissions to the atmosphere by saving

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2262

the fuel. In short, WHR systems will form more

environmental friendly effects by decreasing the amount of exhaust gas emissions produced per power in industrial power plants. Ships are floating energy power plants. They produce energy by their power and propulsion systems while providing safe and economical transportation services from one port to another in their economic life. Moreover, ships require electricity for maneuvering, hotels and operation of all electrical and electronic equipment. All energy requirements of the ships are met by main diesel engines and generators that use fossil fuels. There is much auxiliary machinery powered by electrical energy. In view of all these facts, costs of the energy production on ships reach high levels annually. For this reason, energy saving and energy efficiency on ships cannot be ignored. In addition, implementations have been developed in order to limit the exhaust gas emissions from ships due to international regulations [4] and sanctions are being enforced. (Although afore mentioned regulations cover all environment and air pollution created by ships, only the air pollution is considered because of the scope of this study ) [5,6].

Taking the given facts in consideration, the importance of WHR systems on ships cannot be overestimated. In this study, is introduced a container ship power plant equipped a WHR system which is produced an electricity power by steam turbine (turbo generator) and the effects of the systems on ship energy efficiency and air pollution is also investigated. For this purpose, technical data regarding the sample ship have been gathered and calculations thermodynamic performance is made. In addition, distributions of the WHR, fuel, exhaust gas and pollutant components has been investigated and identified by using a preferable model in the literature. Also it is defined a novel concept called specific emissions ratio (SER) for the performance of emitted to the atmosphere from the WHR system.

MATERIALS AND METHODS

Main propulsion systems of a ship mainly include power machinery that work according to theoretical diesel cycle. On the other hand energy production in WHR system is theoretically based on Rankine cycle. In short, main propulsion systems are operated by ship diesel engines whereas power is produced by steam turbines in WHR systems. Figure 1 shows the WHR system which is produced electricity power by steam turbine of the ship. The exhaust gas boiler is the main part of the WHR system. The boiler consists of the economizer, the evaporator, and the super heater. WHR system extracts heat energy from the exhaust gas by heating, evaporating and

superheating water in heat exchangers in the stack. The feed water is pumped by the feed water pump into the water/steam drum. The heating medium is the saturated water contained in the drum, which is pumped by the economizer circulating water pump. The saturated steam is advanced into the super heater section of the boiler. The superheated steam enters into the steam turbine stages of turbo generator, where it expands producing mechanical power and driving the electric generator. The condensate steam is then pumped into the feed water tank (hot well). A schematic diagram of WHR system and its components analyzed in this study is illustrated in Figure 2. The system is composed of a main diesel.

FIGURE 1

Detail drawing of a WHR system equipped with steam turbine on exhaust gas boiler

FIGURE 2

A schematic diagram of waste heat recovery system and its components analyzed in this study

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2263 FIGURE 3

Net and wasted energy rates of a main engine system without a WHR application (MAN

B&W, 2012).

FIGURE 4

Net and wasted energy rates of a main engine system with a WHR application (MAN B&W,

2012).

engine, an exhaust gas boiler, a steam turbine, a condenser and a pump

Sankey diagrams are a specific type of energy flow diagram, in which the width of the arrows is shown proportionally to the flow quantity. Also, it can be utilized an energy efficiency analysis in a processes. Sankey diagrams are shown in Figure 3 and Figure 4 supplied by a marine engine system without WHR and with WHR applications, respectively. There are 4.9% much more energy can be recovered by main engine machinery on a marine power plant. The main engine of a ship without a WHR system produces 49.1% net power while the rest of the power (50.7%) is used in the

following ways: 2.9% goes to lubrication system, 5.2% goes to jacket cooling water, 25.5% goes to exhaust gas, 16.5% air cooler and 0.6% goes to radiation transfer (Figure 3) [7]. As it can be seen, power produced by burning fossil fuels is much lower than wasted power. In other words, most a lot of the Money spent for energy is wasted. The application of WHR system on the same engine and the ship is shown in Figure 4. As can be seen in the figure, the net power has been increased to 54.2%. It can be understood that this increase is achieved by recovering energy from exhaust gases. As a result, energy wasted through exhaust gases is decreased to 22.9% [8].

Theoretical calculation and analysis of the conversion will be based on diesel and Rankine cycle principles. Furthermore, fuel savings provided by WHR power production and decreases in exhaust gases are also included in the analysis. Also the ISO Standard Conditions are assumed for the calculation methods. An algorithm, given in Figure 5, is prepared in order to simplification understand the calculation methodology and the detailed calculation formulas are given in the follow.

TABLE 1

Specifications of the container ship

Length 295 m

T.E.U. 4,200 -

Breadth 32 m

Draught 12.6 m

Tonnage 55,000 DWT

Service speed 25 knots

TABLE 2

Machinery specifications of the container ship

Type Sulzer 12RTA 84(C)

Bore 84 cm

Stroke 240 cm

Cylinder number 12 -

Speed (Slow

speed) 102 rpm (Full load)

Power 48.6 MW (Full load)

sfoc 168 g/kW.h (Full load)

Fuel consumption 196 ton.day-1

Cruising day 275 day.year-1

For a case study, a container ship which installed on a waste heat recovery system is considered for calculation and real data are used from the ship which properties are shown in Table 1 and Table 2. Net power produced by ship WHR system can be found in the following equation:

NET ME ST

W

_ST

(11)

2264 FIGURE 5

The algorithm of calculation methodology for this study

Where

W

_ME_ME and

W

_ST_ST_S indicate net power produced by main engine in WHR system and steam turbine power by the use of waste heat respectively in terms of kW. The efficiency of the WHR system can be found in the following equation, NET WHR f f

W

m LHV

K

W

NETN f f

m LHV

_f _f (2)

Where

m

_f_f_ff and LHVf indicate the amount of fuel consumption (kg/s) and low heating value of the fuel (kJ/kg) respectively. The purpose of WHR applications is to produce more power by consuming the same amount of fuel. In other words, power production per fuel consumption can be increased by the use of Waste Heat Recovery (kWh/g-fuel). In this way, fuel savings, and decrease in emissions can be achieved. Fuel saving amount (

m&

_FSA) provided by WHR system can be calculated in kg/s as follows,

¸¸

¹

· ¨¨

©

§

ME ST f FSA

W

m

(3)

The steam turbine is utilized the waste heat supplied by main engine exhaust gas for producing energy. In the other words there is no supplemental fuel consumption while the steam turbine producing more energy.

Fuel saving will also lead to decreased exhaust gas emission in proportion to the saved amount.

EGD

m&

³Mass of Exhaust Gas Decrease´, is explained by the correlation between the amount of fuel consumed by ship main engine and resulting exhaust gas flow. Decrease in the exhaust gas is explained as follows,

¸

¹

· ¨

¨

©

§

f exh FSA EGD

m

(4)

where

m&

EGD is expressed in unit of kg/s. In

addition,

m

exhexh is the exhaust gas amount emitted to

the environment by the ship main engine with regard to the fuel that is consumed. Relation between exhaust flow, fuel flow and air flow can be expressed as follows,

f a exh

m

_f

m

_a

m

_exh

m

_f_f

m

_a_a_a_a

m

_e_e (5) When both sides of equation (5) is divided by the fuel flow, the following equation is found,

1

a exh f f

m

aaa

m

exhe f f

m

_ff

m

(6)

when we consider coefficient air flow as

a f

m

O

m

aa f

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2265 TABLE 3

Emission factors (F) on cruising mode for a ship [9,10]

Types of Main Engine Emission Factors in kg/ton-fuel

CO2 CO NOx SO2 VOC PM

High speed diesel engine 3170 7.4 57 54 2.4 1.2

Medium speed diesel engine 3170 7.4 57 54 2.4 1.2

Slow speed diesel engine 3170 7.4 87 54 2.4 7.6

1

exh f

m

O

exh

m

_e

f

m

(7)

:KHUH ȜLVDLU-fuel ratio. In view of equation (6) and (7), equation (4) can be expressed in a simple way,

1 O

FSA EGD

m

. (8) EGD

m&

expression indicates the decrease in exhaust gas amount caused by the fuel saving in a WHR system. However exhaust gas components that are emitted to the atmosphere are also calculated in this expression. Literature survey shows that CO2, CO, NOx, SO2, PM, VOC are the main pollutants in the models and calculations of air pollution caused by ships. Trozzi ve Vaccaro (1998) model that can be used to calculate the amount of ship exhaust gas pollutants is shown below [9].

i jk ijk

jk

E

¦

B

F

. (9)

In this expression i shows the type of exhaust gas pollutants (CO2, CO, NOx, SO2, 3092&« j shows the types of fuels that is used (MDO, F2« k shows the type of ship main engine 0'(67*7«and Ei, shows the total amount

of exhaust gas produced by the ships. The total amount of exhaust gas is usually calculated in terms of (kg/s) or (ton/year). Bjk in equation 4 shows

fuel consumption of a ship with a k type machinery that uses a j type fuel. In addition, Fijk is the

coefficient of the exhaust gas emission factor belonging to i exhaust gas pollutant that is emitted to the atmosphere by a k type machinery in (kg-i/ton-fuel). The values for emission factors which are also referenced by Vaccaro and Trozzi are given in Table 3. Since WHR systems are considered to save money under full load conditions. Table 3 is only arranged according to ship full ahead cruising mode [10-14]. Taking into consideration the notations used in this study, equation (9) can be expressed as follow in (kg/s),

₁₀

3 i FSA i

m

F

E

(10)

where Fi is emission factor (kgi /tonfuel) and shown in Table 3. Decreases in exhaust gas pollutant provided by ship WHR systems have been calculated by using the data in equation (10) and Table 3. The evidence in the calculations is

obtained by using data from the container ship and the WHR system. All the specifications and data regarding the container ship are shown between Tables 1, Table 2 and Table 4.

TABLE 1

Data of the exhaust boiler of the container ship

A new approach is used in this study which is the novel concept for analysis of a power plant equipped with waste heat recovery system. It is well indicate values for comparison the plant with WHR and regardless of WHR. The method is called specific emissions rate (SER). It is defined as amounts of yearly emissions per a unit power produced by power plant in (t/kW.year) and given in follow, j i

W

E

SER

(11)

where Ei explained above.

W&

is the total power values produced by heat engines in a power plant. ( j=marine diesel engine, steam turbine, gas turbine etc.).

RESULTS AND DISCUSSION

In this study is discussed the environmental effects of ship power plant equipped a WHR. For this purpose, technical data regarding the sample ship have been gathered and calculations thermodynamic performance is made. The parameters are real data and taken from the container ship. In addition, distributions of WHR, fuel, exhaust gas and pollutant components has been investigated and identified by using a preferable model in the literature. Also it is defined a novel concept called specific emissions ratio (SER) for the performance of emitted to the atmosphere from a waste heat recovery systems.

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2266 TABLE 2

The results of comparative performance analysis

TABLE 3

Gain the exhaust gas emissions with WHR application in the container ship plant

Type of Plant ŵŽƵŶƚŽĨŵŝƐƐŝŽŶƐŝŶƚ;ǇĞĂƌͿ

Ͳϭ

CO2 CO NOx SO2 VOC PM

Without Waste Heat Recovery 170824 399 4688 2910 129 410 With Waste Heat Recovery 165200 386 4534 2814 125 396

Gain 5624 13 154 96 4 13

TABLE 4

Comparison of annually specific emissions ratio for the container ship power plant

Type of Plant ^ƉĞĐŝĨŝĐŵŝƐƐŝŽŶƐZĂƚĞ;^ZͿŝŶƚ;Ŭt͘ǇĞĂƌͿ

Ͳϭ

CO2 CO NOx SO2 VOC PM

Without Waste Heat Recovery 3.51 0.01 0.10 0.06 0.003 0.01 With Waste Heat Recovery 3.29 0.01 0.09 0.06 0.002 0.01

Table 5 shows that an increase of 1600 kW can be achieved in gross power by using the WHR application. With this power increase, 6.45 tons fuel has been saved per day. This energy saving is achieved by WHR without consuming any fuel. As a result, the net efficiency of the system has risen to 51.8%. With the power increase without fuel consumption environment is also protected. The atmosphere is prevented 190 ton of exhaust gas emissions per day thanks to WHR applications by the container ship main engine. In other words, if the ship main engine produces 50200 kW power, this machine would burn excessive 6.45 ton of fuel per day. As a result, an excessive 190 ton of exhaust gas would be not emitted to the atmosphere.

The benefits from the reduction in total exhaust gas components are shown in Table 6.

As it can be seen in Table 6 there is a decrease in the exhaust gas components emitted to the atmosphere approximately 5905 ton per year in total by WHR systems. Table 7 shows the amount of exhaust gas component per unit power produced by the WHR system. Accordingly the decrease in exhaust gas components per unit power produced by the WHR system is clearly shown. For instance, the value of SER for CO2 gas component is 3.51 t(kW year)-1_{in the application without WHR} whereas the same value goes down to 3.29 t(kW year)-1_{with the application of the WHR. This} system leads to the saving of 0.22 ton of fuel per unit kW power. As a consequently, a SER parameter is an important indications in order to

environmental effects analysis for ship power plants and also thermal plants, nuclear plants, etc.

Also a Sankey diagram for energy balance is drawn and given in Figure 6 to the container ship. Regarding to the case study, the amount of fuel saving and due to the amount of emissions decreased are calculated in the container ship. It is clearly understand from the Figure 6, there is a heat recovery from the exhaust gas approximately 3.3% and produced 1600 kW electricity energy by steam turbine. Therefore, the container ship plant has got a 51.8% total shaft power.

The SER parameter is increase on a power plant; it is mean that environmental effects can be glowingly improved. SER is implied in this study to the container waste heat recovery system and the results are shown in Table 7.

As a consequently the traditional WHR systems are a good solution for recovery of energy with consuming same fuel and due to increased the energy efficiency for power plants. Also a cost of energy saving and an environment effects are decreased when increased of an energy efficiency for a system. But there is a still some heat energy recovery potential from the exhaust gases. This energy cannot be recovery by WHR systems. Some novel technological applications have been developed and installed in shore power plants to recovery this low grade energy. That is we can improve the system and due to increase the energy efficiency much more on ship power plants.

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2267 FIGURE 6

The sankey diagram of case study

CONCLUSION

In this study, the environmental effects of WHR implemented in a sample container ship with diesel engine have been studied. In conclusion, WHR applications enable the production of more power with the same fuel amount. These systems do not consume excessive fuel and more power is produced for the power plant. Despite the common belief, not only saving in the fuel amount and the cost is achieved, but also environment is protected. In this vein, if these types of systems are improved and ship applications are developed, significant steps will be taken.

In view of EEDI that has gone into effect for ships in recent years, WHR applications are of utmost importance. Not only waste heat from exhaust gas boiler, but also other types of waste energy can be identified on ships that is a purpose for the future study. Consequently, benefits can be derived from these types of energy. Thanks to recent research, the application of organic Rankine cycle (ORC) method on ships is possible. ORC has been commonly used in industrial areas. By the use of ORC energy savings can be achieved from waste heat at very low temperatures. Apart from this, absorption cooling systems used in waste heat process can be given as another example.

In brief, ship owners need to examine the current onboard operation conditions and analyze the efficiency of their ships. Then, they need to be able to recover energy from waste heat by using WHR systems. Thus, small investments could lead to substantial profits.

NOMENCLATURE

Abbreviations

MARPOL: International convention for the prevention of pollution from ships

IMO: International maritime organization EEDI: Energy efficiency design index

SEEMP: Ship energy efficiency management plan MEPC: Marine environment protection committee WHR: Waste heat recovery

ISO: International organization for standardization LHV: Low heat value

FSA: Fuel saving amount EGD: Exhaust gas decrease ST: Steam turbine

ME: Ship main engine W: Power production Q: Heat production CO2: Carbon dioxide CO: Carbon monoxide NOx: Nitrogen oxide SO2: Sulfur dioxide PM: Particular matter

VOC: Volatile organic compound E: Exhaust gas pollutants

B: Fuel consumption of a ship F: Emission factors

MDE: Marine diesel engine GT: Gas turbine

MDO: Marine diesel oil FO: Fuel oil

ORC: Organic Rankine cycle Greek Symbols ȘEfficiency Ȝ: Air-Fuel ratio Subscriptions i: Types of pollutants j: Types of fuels

k: Types of ship main engines m: Mass flow rate

f: Fuel a: Air

exh: Exhaust gas

REFERENCES

[1] UNCTAD, (2007). Review of Maritime Transport. Report by the UNCTAD secretariat, United Nations, New York and Geneva, 2007. [2] IMO Marine Environment Protection

Committee (MEPC, 2013), 65th session. Energy-efficiency regulations, London.

[3] Reports of the Energy Efficiency Association (EES) (2010). The Energy Efficiency Strategy Documentation between 2010-2023. Istanbul, Turkey.

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2268 [4] International Convention for the Prevention of

Pollution from Ships (MARPOL), Annex VI, 2005.

[5] Tien, W.K., Yeh, R.H. and Hong, J.M. (2007). Theoretical analysis of cogeneraiton system for ships. Energy Conversion and Management, 48, 1965-1974.

[6] Deniz, C. and Durmusoglu, Y. (2008). Estimating shipping emissions in the region of the Sea of Marmara, Turkey. Science of the Total Environment, 390(1), 255-261.

[7] MAN Diesel & Turbo SE. (2011) TCS-PTG Savings with extra power. Augsburg, Germany.

[8] MAN Diesel & Turbo SE. (2012). Waste Heat Recovery System (WHRS) for reduction of fuel consumption, emissions and EEDI. Germany.

[9] Trozzi C. and Vaccaro R. (1998). 0HWKRGRORJÕHV IRU (VWLPDWLQJ )XWXUH $LU Pollutant Emissions from Ships. Techne report, MEET RF98b.

[10] EMEP, MSC-W Note 1/99. (1999). EMEP emission data, Status Report.

[11] Endresen, Ø., E. Sørgard, J. K. Sundet, S. B. Dalsøren, I. S. A. Isaksen, T. F. Berglen, and G. Gravir. (2003). Emission from international sea transportation and environmental impact. J. Geophy. Res., 108 (17), 1401-1422.

[12] Cooper, D et al., (2004). Methodology for calculating emissions from ships 1. Update of emission factors. SMED Project report (www.smed.se).

[13] Corbett J, Fischbeck P., (1997). Emissions from ships. Science 278(5339), 823-824. [14] EPA420-R-00-002, Analysis of Commercial

Marine Vessels Emissions and Fuel Consumption Data, 2000.

Received: 25.02.2015 Accepted: 19.03.2016

CORRESPONDING AUTHOR

Yalcin Durmusoglu,

Department of Marine Engineering, ITU Maritime Faculty, Tuzla, Istanbul, Turkey.

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ϮϮϲϵ

ASSESSMENT OF NUTRIENTS AND ORGANIC MATTER

IN SEDIMENTS OF DONGPING LAKE, CHINA

Yanhao Zhang1,2_{, Lilong Huang}1_{, Zhibin Zhang}1,3_{*, Yufeng Lv}1_,

Cuizhen Sun1_{, Weimin Wu}3_{, Taha Marhaba}4

1_{College of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan 250101, China} 2_{Co-Innovation Center of Green Building, Jinan 250101, China}

3_{Center for Sustainable Development & Global Competitiveness, Stanford University, Stanford, CA 94305, USA} 4_{John A. Reif, Jr. Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey}

07102, USA

ABSTRACT

Dongping Lake is the second largest freshwater lake in Shandong Province, China. Currently, it is an important reservoir for regulating water for the Eastern Route of South-to-North Water Diversion Project, and the water quality assurance of it is of great importance. The total nitrogen, total phosphorus and organic matters in both surface water and sediment in Dongping Lake were determined to assess the level of contamination. The concentrations of TN, TP and CODCr in the surface water were 0.38±0.06~1.17±0.16, <0.020 ± 0.003 mg/L,14.0±2.1~20.0±3.2 mg/L respectively, lower WKDQ *UDGH ,,, RI WKH ³&KLQD VXUIDFH ZDWHU TXDOLW\ standard (GB3838-´7KHFRQWHQWVRI71DQG TP in sediment in the estuary of Dawen River were higher because of the wastewater drainage from Dawen Rive, while the OM concentration were higher in southwest of Dongping Lake, probably due to the precipitation of dead hydrophytes in the aquaculture area. The result of assessment using enrichment factor method showed that the sediment situated around of Lashan wharf and estuary of Dawen River were moderately severe enrichment of phosphorus, and the sediment at estuary of Dawen River were moderately enrichment of nitrogen, and sediment in all region of Dongping Lake were minor enrichment of organic matters. The result of Geoaccumulation index indicated that sediments in Dongping Lake were uncontaminated to be moderately contaminated.

KEYWORDS:

South-to-North Water Diversion Project, Sediments, Nutrients, Distribution characteristic, Assessment

INTRODUCTION

The contents of nitrogen and phosphorus are known to play a key role in determining the ecological status of aquatic systems [1-5]. Nitrogen

and phosphorus in excess may lead to diverse blooms, loss of oxygen, taste and odour problems, fish deaths and loss of biodiversity [6, 7]. Nitrogen and phosphorus enrichment seriously degrades aquatic ecosytems, impairing the use of water for dringking, industry, agriculture, recreation and other purposes [8]. Several studies in the past have associated oligotrophy with the absence of measurable concentrations of nutrient and have defined eutrophication as a qualitative parameter referring simply to nutrient or organic matter enrichment from external sources and resulting in high biological productivity [9-11]. However, for the freshwater bodies, contaminated sediments are regarded as the most important sources of nutrients leading subsequently to eutrophication [12, 13]. Nutrient release processes have a significant impact on the water quality and may result in continuous eutrophication of lakes and rivers, even when external nutrient sources are under control [14-16]. Phosphorus is a major nutrient controlling eutrophication in many aquatic systems [7, 17]. Along with the rapid economic growth, tourism and industrialization, the sediment P separation can enhance the understanding of P cycling in the aquatic ecosystem [18]. It is believed that controlling P is the best approach for reducing eutrophication [19].

Dongping Lake is a adjusting and important freshwater lake on the Eastern Route of the South-to-North Water Diversion (SNWD) project, and the location of the lake is very important for the project [20]$FFRUGLQJWRWKH³:DWHU3ROOXWLRQ3UHYHQWLon Planning of SNWD Project for Shandong (China) 6HFWLRQ´ LWV ZDWHU TXDOLW\ VKRXOG PHHW WKH *UDGH ,,, RI WKH ³&KLQD VXUIDFH ZDWHU TXDOLW\ VWDQGDUG (GB3838±´ 6R WKH ZDWHU TXDOLW\ LV WKH PRVW important element in the success of the Eastern Route of the SNWD [21]. Dawen River is the main river flowing to Dongping Lake. Domestic sewage and industrial waste water without treatment from cities (Laiwu, Xintai, Feicheng, Ningyang and Dongping) has discharged into Dawen River last century 90s. Therefore, investigation of the nutrients and organic matter distribution

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characteristics of the water and surface sediments in Dongping Lake is clearly essential. There was some previous research on phosphorus distribution in sediment of Dongping Lake [22-24], while, there is still a lack of investigation of nitrogen and organic matters pollution for the water and sediments in Dongping Lake.

Therefore, this paper will systematically investigate the distributions of total nitrogen (TN), total phosphorus (TP) and organic matter in the water and sediment and assess of sediment contamination in Dongping Lake. This work lays groundwork towards a comprehensive understanding of the current nutrient levels of Dongping Lake and provides essential knowledge for establishing appropriate water quality management policies and remediation strategies.

MATERIALS AND METHODS

Study area. As shown in Fig.1 (left), the water of Yangtze River water will be transported more than 1100 km from Yangzhou to Tianjin and Beijing in the SNWD project. Dongping Lake in the red circle, an important reservoir (35°30' ̚ 36°20'N, 116°00' ̚ 116°30'E), serves serve a pivotal role in the Eastern Route of SNWD of China and water transmission from the west to the east of Shandong Province. Additionally, the lake plays a major role in regulating the Yellow River

and Dawen River floods. Dongping Lake is the second largest fresh-water lake in Shandong Province, China, and also the only large natural LQODQG ODNH VWLOO H[LVWLQJ DIWHU WKRXVDQGV RI \HDUV¶ geological and morphological changes in the lower reaches of the Yellow River [21]. The current size of the lake, including the old and the new lake, is about 627 km2_{. The multi-annual mean water depth} of the lake is 2-4 m, with a perennial area of 124 km2_{. The recharge coefficient of the lake is 61.2,} and the total storage volume is 4.0 billion m3_. Depth varies slightly annually and seasonally. Recharge to Dongping Lake relies mainly on surface runoff via the Dawen River. The water in the lake flows north through the Xiaoqing River and enters the Yellow River. Dongping Lake is being utilized for flood control, irrigation, water supply, aquatic breeding and tourism [21].

Sampling sites. As shown in Fig.1, Dawen River, a main tributary, originates in north of Xuangu Mountain, and collects water from branches of the Tai-Yimeng mountain range. Affected by the terrain, Dawen River winds its way from west to east, and then flows into Dongping Lake. Then, the water run through the lake from south to north, out of the lake in the north, and flew into the Yellow River. Driven by the natural hydraulic flow, nutrients are transported from the upstream lake to the downstream lake as indicated by the arrow in Fig. 1. In this study, surface

FIGURE 1

Geographic map of Dongping Lake and sampling sites (Right: A-downstream lake, B-Center of the lake, C-Estuary of Dawen River, D-Southwest of the lake (aquaculture area).

Taian Jinan Liaocheng Jining Heze Dongying Tianjin Yellow Ri ver Dawen River Dongping Lake Taian Dawen River 36¡ ã6¡ ä0¡ åN 35 ¡ã57 ¡ä0¡ åN 116¡ã9¡ä0¡åE 116¡ã15¡ä0¡åE Flow City N 5 10Km 0 N A B D C A Sampling site Area 116¡ã15¡ä0¡åE 36¡ ã6¡ ä0¡ åN 35 ¡ã57 ¡ä0¡ åN 116¡ã10¡ä0¡åE Dongping Lake (new) Beijing Dezhou Yello w Yangze River Rive r Beijing Eas te rn Route of SN DW Eas tern Route of SN DW 20 40Km 0

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TABLE 1

Water quality and its characteristics of the sampling fields

Site fields Salinity ˄mg/L ˅ DO pH Transparenc y ˄cm˅ Water depth ˄m˅ Other details C-Estuary of Dawen River 524±22 6.91±0.3 4 7.0±0. 3 30±15 1.2±0.6 lots of wharf D-Southwest of the lake 451±20 9.25±0.6 1 6.5±0. 3 35±10 2.8±0.4 aquaculture region B-Center of the lake 470±16 7.01±0.3 0 6.5±0. 2 31±10 2.3±0.5 A-Downstream of the lake 426±12 8.74±0.2 6 7.0±0. 4 65±10 3.0±0.6 effluent water flowing to Yellow River sediment samples (0-20 cm below the water±

surface interface) and the surface water (0-20 cm below the water surface) were collected respectively at 15 sites across the lake to study the spatial distribution of nutrient contents within the lake. The samples were mainly located at the downstream of the lake (A area), the center of the lake (B erea), the estuary of Dawen River (C area), and the southwest of the lake (D area), respectively (Fig.1 right).

The salinity, DO, pH, and transparency for the water were shown in Table 1. The salinity, DO and pH of water in Dongping Lake were 426f12~524 f22mg/L, 6.91f0.34~9.25f0.61 mg/L and 6.5f 0.2~7.0f0.3, respectively.

Sampling collection and analysis. Surface layer sediment (0-20 cm) samples were collected with a home-made core Plexiglas sampler from the aforementioned sampling sites in April, 2012. The samples collected from each site consisted of 3 parallel samples. Following collection, the samples were sealed in plastic bags and stored in a refrigerator at 4o_{C without exposure to light.} Sediment samples were air dried for 30 day at room temperature with exposure to the day light. Then, the large solid components (stones and plant) were removed by a 0.15-mm sieve. The sieved samples were stored in air-sealed plastic bags before further analysis. At the same time, the surface water samples were collected, and stored in 500 ml polyethylene bottles at a cooler at 4o_{C. All of the} samples were sent to Environmental Laboratory, Shandong Jianzhu University for further analyses.

TN, TP. and CODCr in the water were GHWHUPLQHGDFFRUGLQJWR³0HWKRGVIRUH[DPLQDWLRQ RIZDWHUDQGZDVWHZDWHU´[25].

Sediment samples were air dried at room temperature in daylight. Then, the large solid debris (such as stones and plant) in the dried samples was removed by a 100 mesh sieve. The sieved samples were stored in air-sealed plastic bags before further analysis.

To measure TP in the sediment samples, 0.25 g sediment samples were digested in Teflon vessels with 12 mL HNO3 (65%): HCl (37%) = (3:1) mixture in a microwave oven (MARS X-press, CEM) [26, 27]. Then, TP in acid digested extract was determined by the ascorbic acid method using a Shimazu spectrophotometer (UV3600) [28]. TN was determined using an elemental analyzer (CE440, Exeter Analytical, Inc., North Chelmsford, MA, USA). To measure OM, the sediment samples were first dried at 60o_{C for 24 h to remove moisture} [29]. Then, the samples were weighed and heated in a muffle furnace at 550o_{C for 2 h to further remove} OM. Finally, the sediment samples were re-weighed to calculate OM percentage, which was the difference between the ash weight and dry weight divided by the dry weight. All samples were analyzed in triplicate, and the results were expressed as mean and standard deviation.

All samples were analyzed in triplicate, and the results were expressed as mean and standard deviation. SURFER software (Golden Software Inc.) is used to analyze the spatial distribution of sedimentary TN, TP and OM in Dongping Lake.

Assessment of sediment contamination. Enrichment factor (EF) and Geoaccumulation index (Igeo) were mainly used to assess the degree of heavy metal contamination in sediments. In this study, we evaluated the TN, TP and OM in sediments of Dongping Lake using modified EF and Igeo.

EF. EF is defined using the relationship below (Eq. (1)) [30]:

EFi=Ci/CBV (1)

EFi is the enrichment factor of the nutrient i. Ci is the concentration of the nutrient i in sediment samples and CBV is the environmental background value. In this paper, CBV value was obtained from annual monitoring for Dongping Lake sediment [31]. Depending on the calculated values of EF, the sediment contamination can be classified as no enrichment when EF<1, minor enrichment when EF

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is 1~3, moderate enrichment when EF is 3~5, moderately severe enrichment when EF is 5~10, severe enrichment when EF is 10~25, very severe HQULFKPHQW ZKHQ () LV í DQG H[WUHPHO\ severe enrichment when EF is >50 [30].

Igeo. Igeo is calculated by the following equation (Eq. (2)) [6]:

Igeo = Log2(Cn)/[1.5(Bn)] (2)

Cn is the concentration of the nutrients in sediment samples and Bn is the background concentration of the nutrient. Factor 1.5 is the background matrix correction factor due to lithospheric effects. The Igeo consists of seven classes [32]. Igeo LV SUDFWLFDOO\ XQFRQWDPLQDWHG 0<Igeo LV XQFRQWDPLQDWHG WR PRGHUDWHO\ contaminated; 1<IgeoLVPRGHUDWHO\FRQWDPLQDWHG 2<Igeo LV PRGHUDWHO\ WR KHDYLO\ FRQWDPLQDWHG 3<Igeo is heavily contaminated; 4<Igeo LV heavily to extremely contaminated; 5<Igeo is extremely contaminated [33].

RESULTS

Nutrient and COD concentrations in surface water. Mean concentrations of nutrients and CODCr in surface water samples at each sites in this study, and maximum concentrations reported from previous studies were shown in Table 2.

As shown in Table 2, TN concentrations in the surface water ranged from 0.38±0.06~1.17±0.16 mg/L, and CODCr concentrations ranged from

14.0±2.1~20.0±3.2 mg/L, TP concentrations varied from 0.00±0.00~0.020±0.003 mg/L. The higher TN and CODCr concentrations were recorded at sites 5, 6 and 8 situated the estuary of Dawen River. TP concentrations at each site were all low. The highest TN concentration was more than two times higher than the lowest TN concentration, while the highest CODCr concentration was only a little higher than the lowest CODCr concentration. Except the TN concentrations in sites 5, 6, 8 exceeded the standaUG YDOXHV RI *UDGH ,,, LQ WKH ³&KLQD VXUIDFH water quality standard (GB3838-´ DOO WKH concentrations of TN, TP, CODCr can meet the Grade III standard values in China. Compared with the maximum concentrations reported by previous studies conducted in the same area [34, 35], the water qualities of TN and TP were improved greatly in recent.

TN, TP and organic matter concentrations in surface sediments. As shown in Fig.2a and Fig.2b, the distribution pattern of TN was in the range of 426.0±52.3~839.0±123.0 mg/kg, with an average of 647.0±87.6 mg/kg. TP contents in sediments were in the range of 167.0±23.4~488.0±63.2 mg/kg, with an average of 336.0±43.2 mg/kg. Concentrations of TP in sediment of Nansi Lake were 759.0~896.0 mg/L, and mean of 816.0 mg/L [28], was obviously higher than those of Dongping Lake. Sites of higher TN and TP concentrations were found in the southeast of Dongping Lake, which are the estuary of Dawen River.

TABLE 2

Mean concentrations of nutrients and COD in surface water samples at typical sites in this study, and concentrations reported for previous studies

Sites

Mean concentrations of nutrients and CODCr (mg/L)

TN TP CODCr References 1 0.38±0.06~ 0.00±0.000 14±2.1 This study 2 0.82±0.11 0.01±0.002 16±2.4 3 0.99±0.14 0.02±0.003 15±1.7 4 0.51±0.12 0.01±0.002 11±1.2 5 0.62±0.06 0.01±0.002 14±1.8 6 0.70±0.03 0.01±0.002 15±2.1 7 0.68±0.05 0.01±0.001 13±1.2 8 0.63±0.06 0.01±0.002 13±1.5 9 1.12±0.18 0.01±0.002 17±2.1 10 1.17±0.16 0.01±0.002 15±2.8 11 1.36±0.23 0.01±0.001 20±3.2 12 0.43±0.06 0.02±0.003 16±2.6 13 1.02±0.15 0.01±0.001 16±1.8 14 1.02±0.15 0.01±0.001 17±2.2 15 1.06±0.15 0.01±0.001 15±2.1 4.75±0.76 0.10±0.002 -- [34] 1.34-14.60 0.081-0.182 44-65.6 [35]

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FIGURE 2

Distribution of TN and TP contents in surface sediments of Dongping Lake (a. TN; b, TP)

The distribution of OM in surface sediments of Dongping Lake was shown in Fig.3. OM contents in sediments were in the range of 48981.0±6435.2~124924.0±18943.6 mg/kg, with an average of 87658.0±12653.1 mg/kg. Concentrations of OM in sediment of Nansi Lake

were mean of 118300.2 mg/kg [28]. Thus, the OM concentrations in sediment of most Dongping Lake were lower than in Nansi Lake. Sites of higher concentrations were at southwest of Dongping Lake.

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FIGURE 3

Distribution of OM contents in surface sediments of Dongping Lake

DISCUSSION AND CONCLUSIONS

Distribution characteristics of TN, TP and OM in sediments. Nutrients of Dongping Lake mainly come from industrial wastewater, domestic sewage and surface runoff of Dawen River basin and valleys of Dongping Lake and so on [22, 36]. According to an estimation, the most important sources of nutrients is Dawen River and input of the river accounts for about 82.61% of the total phosphorus input, were higher than valleys of Dongping Lake (14.47%) [22]. According to statistics, industrial and urban household wastewater discharge was about 1.64×104_t/a, CODCr was 6.42×104 t/a, and most of the discharging wastewater was worse than Grade V during 1995~2004. Some studies also showed that phosphorus in industrial wastewater and domestic sewage discharge of Dawen River have increased these years, and the input of TN and TP from Dawen River were 4218 t/a and 161 t/a, respectively. However, the TN and TP in the Lake from the aquaculture and others only accounted for 17.6% and 17.4%, respectively [36]. So, the sites of higher TN and CODCr concentrations in water, higher TN and TP concentrations in sediment were mainly located at the estuary of Dawen River, mostly due to the wastewater from the upstream of Dawen River.

The concentrations of OM in sediment at southwest of Dongping Lake were higher than other regions, probably due to that there were the precipitation of lots of dead hydrophytes at the southwest regions when sediment samples were collected.

Assessment of TN, TP and OM for sediments. EFs of TN, TP and OM for sediments. As shown in table 3, the results suggested that the pollution extent of the sediment decreased from the upstream to the downstream in the lake. The phosphorus were moderately severe enrichment (5<EF<10) in the sediments at sites around the estuary of Dawen River. The nitrogen were moderately enrichment (3<EF<5) in the sediments of sites around of estuary of Dawen River. The organic matters were minor enrichment (1<EF<3) in the sediments of all lake.

Igoes of TN, TP and OM for sediments. As

shown in table 4, the Igoes (0<Igoes<1) showed that the sediments of all sites were uncontaminated to moderately contaminated by nitrogen, phosphorus and organic matters. The Igoes of TN and TP in sediments around the southeast of Dongping Lake were greater than those in other sites, while the Igoes of OM in sediments around the southwest of the Lake were greater. The sites with

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TABLE 3

EFs of TN, TP and OM for sediments of all sites in Dongping Lake

Sites EF TP TN OM 1 3.64 1.80 1.52 2 6.98 2.25 1.96 3 2.86 1.85 2.11 4 2.78 2.10 1.86 5 4.14 1.65 2.55 6 3.54 1.76 1.85 7 3.78 1.82 2.02 8 3.50 1.96 2.65 9 7.16 2.77 1.34 10 7.25 3.25 1.00 11 8.34 3.25 1.39 12 1.95 1.90 1.68 13 5.60 2.15 1.80 14 3.98 2.25 2.10 15 5.92 2.66 2.54

higher contents of TN and TP in sediments were probably caused by the reason that the southeast of Dongping Lake was the estuary of Dawen River, which has been brought lots of nitrogen and phosphorus to the lake since 1980s [31]. The higher OM in sediments probably was due to cage culture in the southwest region of the lake, which resulted in the precipitation of lots of aquatic plants in the winter.

The distribution and pollution level of nutrients in the surface water and sediment in

Dongping Lake were investigated. The result showed that all the concentrations of TN, TP, CODCr in the lake water could meet the Grade III VWDQGDUGYDOXHVRIWKH³&KLQDVXUIDFHZDWHUTXDOLW\ standard (GB3838-´ H[FHSW RI 7N contents a little bit higher over the standard value in the estuary of Dawen River. And the higher concentrations of TN and TP in the sediment were also recorded at the estuary of Dawen River. The higher OM concentrations were found at southwest

TABLE 4

Igoes of TN, TP and OM for sediments of all sites in Dongping Lake

Sites Igoe TP TN OM 1 0.045 0.014 0.00021 2 0.051 0.014 0.00022 3 0.043 0.014 0.00022 4 0.048 0.014 0.00021 5 0.046 0.014 0.00023 6 0.051 0.014 0.00022 7 0.047 0.014 0.00022 8 0.042 0.014 0.00021 9 0.051 0.015 0.00022 10 0.051 0.015 0.00021 11 0.052 0.015 0.00022 12 0.040 0.014 0.00022 13 0.045 0.015 0.00022 14 0.046 0.015 0.00023 15 0.049 0.015 0.00023

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of Dongping Lake, probably due to the dead plants resulted from the aquaculture.

The EFs showed that phosphorus in sediment situated at the estuary of the Dawen River, which were moderately severe enrichment. While the nitrogen in sediment at the estuary of Dawen River were moderately enrichment and the organic matters in sediment of Dongping Lake were minor enrichment. From the analysis of the Igoes indexes, the sediments in Dongping Lake were in pollution JUDGH RI ³XQFRQWDPLQDWHG WR PRGHUDWHO\ contaminDWHG´ ZLWK QLWURJHQ SKRVSKRUXV DQG organic matters.

ACKNOWLEDGEMENTS

This study was funded by the Department of Environmental Protection of Shandong Province (No.SDHBPJ-ZB-09) and Natural Science Foundation of Shandong Province for providing the financial support (No. BS2013HZ028). Special thanks to Mr. Zhang for assistance with the proofreading of this manuscript.

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[13] Wu, Y., Hu, J., Jin, X., Ke, P., Chen, X., and Liu, J. (2005) Chemical characteristics of nitrogen and phosphorus in the sediments of the typical bays in Dianchi Lake and calculation of their dredging layers, Journal of Environmental Science (in Chinese with English Abstract) 26, 77-80.

[14] Abrams, M. M., and Jarrell, W. M. (1995) Soil-Phosphorus as a Potential Nonpoint-Source for Elevated Stream Phosphorus Levels, Journal of Environmental Quality 24, 132-138.

[15] Tian, J. R., and Zhou, P. J. (2007) Phosphorus fractions of floodplain sediments and phosphorus exchange on the sediment-water interface in the lower reaches of the Han River in China, Ecological Engineering 30, 264-270. [16] Xie, L. Q., Xie, P., and Tang, H. J. (2003)

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Calculation and temporal variability of ventilation coefficient depending on location and characteristics of houses in Balikesir city center

FEB - FRESENIUS ENVIRONMENTAL BULLETIN

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