Marine environment status assessment based on macrophytobenthic plants as bio-indicators of heavy metals pollution

MPB-08461; No of Pages 8 Marine Pollution Bulletin xxx (2017) xxx–xxx

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Marine environment status assessment based on macrophytobenthic plants as bio-indicators of heavy metals pollution Tamara Zalewska ⁎, Beata Danowska Institute of Meteorology and Water Management - National Research Institute, Maritime Branch, Waszyngtona 42, 81-342 Gdynia, Poland

a r t i c l e

i n f o

Article history: Received 3 January 2017 Received in revised form 27 February 2017 Accepted 28 February 2017 Available online xxxx Keywords: Heavy metals Baltic Sea Environment status assessment Macrophytobenthic plants

a b s t r a c t The main aim of study was to develop the environmental quality standards (EQSMP) for selected heavy metals: Pb, Cd, Hg and Ni bioaccumulated in the tissues of marine macrophytobenthic plants: Chara baltica, Cladophora spp., Coccotylus truncatus, Furcellaria lumbricalis, Polysiphonia fucoides, Stuckenia pectinata and Zanichellia palustris, collected in designated areas of the southern Baltic Sea in period 2008–2015. The calculated concentration ratios (CR), which attained very high values: 104 L kg−1 for lead, 103 L kg−1 for nickel and mercury and even 105 L kg−1 for cadmium formed the basis for the determination of EQSMP values. The EQSMP values were: 26 mg kg−1 d.w. for Pb, 33 mg kg−1 d.w. for Cd, 32 mg kg−1 d.w. for Ni and 0.4 mg kg−1 d.w. for Hg. The application of macrophytobenthic plants as bioindicators in marine environment status assessment of certain areas of the Baltic Sea is also described in the paper. © 2017 Elsevier Ltd. All rights reserved.

1. Introduction Natural environment, including the marine environment, is exposed to continuous human activities related pressure. It is well known that to register any changes undergoing in the environment it is necessary to monitor specific elements corresponding to the anthropogenic pressure. Monitoring results, in turn, forms the basis for measures aiming to improve or maintain the good environmental status. Implementation of legal acts on the international scale is one of the main directions leading to the improvement of the environmental status. The activities of the Baltic Sea countries within the Convention on the Protection of the Marine Environment of the Baltic Sea Area, known as the Helsinki Convention are an outstanding example of such cooperation. In Europe, there are recent examples of even wider and more restrictive legal acts like: the Water Framework Directive (WFD) - a major directive in the field of water policy (Anon, 2000), and the Marine Strategy Framework Directive (MSFD) - establishing a framework for community action in the field of marine environmental policy (Anon, 2008). The transposition of those Directives to national jurisdiction of the Member States implies the obligation to monitor and assess the status of waters, including marine areas, and to establish adequate measures to maintain the good environmental status of waters or improve it. Hazardous substances, presence of which in the natural environment is continually growing, in respect of both the number and the diversity, belong to the key points in marine environment pollution monitoring. The data on hazardous substances' concentration levels in ⁎ Corresponding author. E-mail address: [email protected] (T. Zalewska).

the marine environment constituents provide information on actual pollution, however they do not allow for determining direct changes the ecosystem is undergoing. To assess the status of the marine environment certain threshold values – border concentrations, also called reference values or relative concentrations – have to be established which would delimit the good environmental status (reference status). Good environmental status is assumed if the concentrations of hazardous substances do not cause any disturbances in functioning of the ecosystem. Specification of the threshold values is a demanding task (eg. SEPA, 2000, OSAPR, 2009). In the case of abiotic elements the most common approach is to apply the historic data mining, or to use the concentrations levels specific to undisturbed conditions and characteristics of the ecosystem (COAST, 2002, Babut et al., 2003, Maggi et al., 2008). In regards to marine organisms, in an ideal situation, the reference values could be determined by studying the correlation between the substance concentration and the effect it produced. Macrophytobenthic plants, which are one of the key marine biotic elements, are commonly used as a bioindicator of environmental status (e.g. Bondareva et al., 2010, Burger et al., 2006, Chakraborty et al., 2014). The occurrence of certain species, specific to an area, as well as their biomass quantity, might be indicative of the good environmental status, relating to optimal habitat conditions. Besides the positive, desirable plant species, opportunistic plants appear in the marine environment, indicating a deterioration of environmental conditions, e.g. due to increased concentration of nutrients (Osowiecki et al., 2012). The plants can also serve as accumulation bioindicators owing to their outstanding accumulation properties, due to which macrophytobenthic plants deserve particular attention as nearly ideal bioindicators of the environmental status

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Please cite this article as: Zalewska, T., Danowska, B., Marine environment status assessment based on macrophytobenthic plants as bioindicators of heavy metals pollution, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.02.075

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T. Zalewska, B. DanowskaMarine Pollution Bulletin xxx (2017) xxx–xxx

(e.g. Carlson & Erlandsson, 1991, Carlson & Holm, 1992, Rainbow, 1995, Leal et al., 1997, Ostapczuk et al., 1997, Kruk-Dowgiałło, 1998, Muse et al., 1999, Malea & Haritonidis, 2000, Sawidis et al., 2001, Topcuoğlu et al., 2003, Burger et al., 2006, 2007, Żbikowski et al., 2007, Zalewska & Saniewski, 2011, Zalewska, 2012a, 2012b, Zalewska & Suplińska, 2012, Chakraborty et al., 2014). Their response to environmental disturbance, including increase of pollutant concentrations in their direct environment, is very fast because they assimilate nutrients and other substances directly from seawater. This direct exchange of elements, without intermediate stages, is facilitating the interpretation of results (Szefer, 2002). Macrophytobenthic plants, as secured to the substratum, occur in defined areas, hence they are reflecting the status of the given area. The application of macrophytobenthic plants for the environmental status assessment regarding pollution with hazardous substances, especially heavy metals, presents an alternative to the method based on analyses of their concentrations in water. Analytically, the direct measurements of trace concentrations of metals in seawater, is highly erratic, and above all it requires advanced analytical equipment guaranteeing the limits of quantification allowing for measuring trace concentrations with respectively low uncertainties. Application of macrophytobenthic plants as bioindicators in environmental status classification requires setting up so-called target values, i.e. concentrations defining the border between good and inadequate environmental status. Target values form the Environmental Quality Standards (EQS) for the monitored substances content in plant tissues. It has to be borne in mind that setting a sharp threshold delimiting the good and inadequate status is an uncompromising method, which might pose certain risk of drawing incorrect conclusions due to simplified parameterization and incomplete picture of the ecosystem complexity and possible interactions between the polluting substances and living tissues. In an ideal situation, the good environmental status with respect to heavy metals should represent environment where the respective concentrations of these substances do not cause any dysfunctions in biotic elements of the assessed ecosystem. The heavy metals: Pb, Cd, Ni and Hg, concentrations of which are to be monitored by applying accumulation bioindicators, have been selected in consideration of the recommendations of the EU Directive 39/ 2013/UE from 13 August 2013, amending Directives 2000/60/EC and 2008/105/EC as regards priority substances in the field of water policy

(Anon, 2013). Additionally, Pb, Cd and Hg are formally accepted core indicators by the HELCOM CORESET Project (HELCOM, 2012). The presented study was aimed at developing a set of environmental quality standards for metals Cd, Pb, Ni and Hg in certain macrophytobenthic plant species for their application in marine environment status assessment and classification. 2. Materials and methods 2.1. Sampling Benthic plants were collected in the southern Baltic Sea, at four locations: Klif Orłowski, Jama Kuźnicka, Rowy and Słupsk Bank (Fig. 1). Sampling was conducted by a scuba diver who collected the plants from the seafloor at different sampling depths, depending on location. In the Klif Orłowski area, the plants were collected at depths from 1 m to 8 m, in Jama Kuźnicka – 1 m to 4 m, in Rowy – 6 m and 7 m, and in the Słupsk Bank at 14 and 15 m depth. The sampling had been conducted twice a year, in June and in September or October to follow seasonal changes, from 2008 to 2015. The collected samples, secured in plastic bags, were transported to the laboratory for further processing. 2.2. Description of sampling areas In the southern Baltic Sea, macrophytobenthic plants occur in areas with specific hydro-morphological properties. Macrophyte monitoring in the Polish sector of southern Baltic Sea has been conducted since 2000 (Krzymiński et al., 2001, Miętus et al., 2009, Jakusik et al., 2013). Macrophytes are collected at four locations representative of various water types (Fig. 2). Three of these sampling sites have been set up in transitional and coastal waters following the implementation of Water Framework Directive (WFD) (Krzymiński et al., 2004). The area of Jama Kuźnicka (JK) is representing a transitional water body – Puck Lagoon; Klif Orłowski (KO) also represents a transitional water body – outer Puck Bay, while the boulder area of Głazowisko Rowy (RO) is located in the costal water body (Krzymiński et al., 2004). Another macrophyte sampling site (ŁS) is located within the Słupsk Bank, a shoaled area in the off shore region; this area belongs to the Bornholm Basin – an assessment subbasin distinguished in the HELCOM Monitoring and Assessment Strategy – MAS (HELCOM, 2013) regarding the MSFD regional assessment scheme. According to the HELCOM MAS,

Fig. 1. Sampling locations of macrophytobenthic plants for heavy metal determination.

Please cite this article as: Zalewska, T., Danowska, B., Marine environment status assessment based on macrophytobenthic plants as bioindicators of heavy metals pollution, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.02.075

T. Zalewska, B. DanowskaMarine Pollution Bulletin xxx (2017) xxx–xxx

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Fig. 2. Environmental status assessment of the plant sampling areas according to 5-class scale where blue is very good status and green is good status. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Jama Kuźnicka and Klif Orłowski belong to the Polish coastal waters subbasin of the Gdańsk Basin and the boulder area Rowy belongs to the Polish coastal waters subbasin of the Bornholm Basin (HELCOM, 2013).

Parallel to environmental samples trace elements were analyzed in certified reference material: Mixed Polish Herbs (INCT-MPH-2) (Table 1) for quality assurance purposes.

3. Results and discussion 2.3. Sample preparation 3.1. Bioindicator choice In land laboratory, the collected plant material was washed 4–5 times in trays filled with distilled water of volume not less than two liters. Then material was analyzed taxonomically. Individual species occurring in the samples were identified, separated and placed in plastic string bags. In such form the samples were frozen. Taxonomic analyses and biomass determination were carried out according to the HELCOM COMBINE guidelines (HELCOM, 1997). For heavy metal determination, the selected plant species were freeze-dried to avoid mercury losses. The dry biomass of each species was determined gravimetrically. At this point a sub-sample was taken for Hg analyses and the remaining material was ashed in platinum vessels at 450 °C. The ashed samples were then mineralized in ultra-pure nitric acid in a Milestone Ultra Wave mineralizer, allowing running the process at temperature of ca. 300 °C and pressure up to 200 bars. Glassware used for the sample preparation was cleaned with ultra-pure nitric acid with concentration of approx. 10% by 3 days. Before the direct use, glass was rinsed several times with deionized water.

2.4. Analysis and measurement Mercury content in freeze-dried plant samples was determined using an atomic absorption spectrometer – AMA 254 analyzer. Lead, cadmium and nickel were determined with a flame atomic absorption spectrometer - Scientific ICE 3300.

The initial stage in target value setting procedure is the selection of the right bioindicators. The macrophytobenthic plants meeting the requirements of a good bioindicator have been selected in long term studies on heavy metals bioaccumulation (Zalewska, 2015). The most important criteria taken into account were the bioaccumulative capacity of the species and its representativeness for the area. Bioaccumulation efficiency and response proportionality, indicating that the change of concentrations in plant tissue is proportional to those in the surroundings, are other properties characterizing good bioindicator (Haritonidis & Malea, 1995, Rajfur et al., 2010, Chakraborty et al., 2014). The selection criterion regarding species representativeness for the assessed area was based on species natural occurrence in the transitional, coastal and offshore areas (Fig.2). Species biomass was taken into account as well as occurrence frequency. Table 1 Certified values and measured concentrations of heavy metals in Mixed Polish Herbs certified material (INCT-MPH-2). Metal

Certified value (mg kg−1 dw)

Measured value (mg kg−1 dw)

RSD %

Recovery %

LOQ (mg kg−1 dw)

Hg Cd Pb Ni

0.0176 ± 0.00176 0.199 ± 0.015 2.16 ± 0.23 1.57 ± 0.16

0.0181 ± 0.0011 0.204 ± 0.017 2.05 ± 0.018 1.45 ± 0.047

2.84 2.51 5.00 7.64

102.8 102.5 95.0 92.4

0.001 0.025 0.50 0.10

RSD – relative standard deviation. LOQ - Limit of Quantification.

Please cite this article as: Zalewska, T., Danowska, B., Marine environment status assessment based on macrophytobenthic plants as bioindicators of heavy metals pollution, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.02.075

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T. Zalewska, B. DanowskaMarine Pollution Bulletin xxx (2017) xxx–xxx

The final set of plants contained 7 species; three species representing red algae group – Polysiphonia fucoides, Furcellaria lumbricalis and Coccotylus truncatus, specific to the boulder areas: Klif Orłowski, Rowy and Słupsk Bank; two species of vascular plants: Stuckenia pectinata and Zanichella palustris, and Chara baltica, a charophyceae, specific to Jama Kuźnicka. However, red algae were also encountered in Jama Kuźnicka sampling area and a chlorophyta – Cladaophora spp. was found in great abundance. Cladophora spp. was also occurring in Klif Orłowski sampling spot. 3.2. Concentration ratio – CR The determination of EQS starts with the establishment of concentration ratio (CR), a unique attribute characterizing the macrophyte species. Concentration ratio is a ratio between pollutant concentration in plant tissue (CMP) to that in the seawater (CSW) (Eq. (1)) (IAEA, 2014). It is a quantitative measure of the plants bioaccumulative capacity (Leal et al., 1997, Szefer, 2002, Zalewska & Saniewski, 2011, Zalewska & Suplińska, 2012, Zalewska, 2012a, 2012b). Concentration ratios form the basis of risk assessment of harmful effects caused by hazardous substances on specific biota (IAEA, 2014). The application of CR values, however, reveals certain limitations, one of which is the fact that CR values are indicative of the equilibrium phase, while in the monitoring measurements this condition is not always met. Nonetheless, to determine CR values both, the concentrations of metals in plant tissues as well as in seawater, being the direct source of ion supply assimilated by plants have to be analyzed. CR ¼

C MP C SW

ð1Þ

3.2.1. Concentrations of heavy metals in plant tissue In the years 2008–2015 the concentrations of Pb, Cd, Ni and Hg in plant tissues were measured in seasonal sequence (Table 2) to provide information on seasonal variations as well as annual changes (Zalewska, 2012a). The plants were sampled at different water depths, because the concentrations of bioaccumulated elements vary in the vertical profile, depending mainly on the biomass (Zalewska, 2012a, 2012b). In CR calculations, the mean concentrations determined for different species were used and concentration variability was reflected in SD values (Table 2). Relatively high concentrations of all analyzed metals were detected in the tissues of P. fucoides as compared to other species (Table 2). P. fucoides proved one of the highest bioaccumulation ability, that results mainly from its morphology, fine tissue structure and exceptionally large exchange surface, which define its efficiency of substances exchange with the environment (Zalewska, 2012a, Zalewska, 2012b, Zalewska, 2015). The maximal mean concentration of Pb (7.6 mg kg−1 d.w.) was found in P. fucoides, while the vascular plants – S. pectinata and Z. palustris – contained only ca. 2 mg Pb kg−1 d.w. and the remaining plant species (Ch. baltica, Cladophora spp., C. truncatus and F. lumbricalis) contained even less of this metal, 1.4–1.6 mg kg−1 d.w. The maximal content of Cd (5.6 mg kg−1 d.w.) was measured in C. truncatus. The red algae contained: P. fucoides - 3.7 mg Cd kg− 1 d.w. and F. lumbricalis - 2.4 mg Cd kg−1 d.w., and vascular plants S. pectinata and Z. palustris - 1.9 and 2.8 mg Cd kg−1 d.w., respectively. The least amounts of cadmium were determined in Cladophora spp. (0.5 mg kg−1d.w.) and Ch. baltica (0.7 mg kg−1 d.w.). In the case of both Pb and Cd, the considerable range of concentrations (SD) in plant tissues indicated the seasonal variability and biomass effects.

Table 2 Mean concentrations of heavy metals in macrophytobenthic plants, concentration ratios (CR) and environmental quality standards (EQSMP) derived for Pb, Cd, Ni and Hg in the analyzed species. Species

n

Location

Month

Year

Metal

Mean concentration (mg kg−1dw)

SD

CR (dm3 kg−1)

EQSMP (mg kg−1dw)

Chara baltica

9

Jama Kuźnicka

June September

2010, 2013, 2014, 2015

Cladophora spp.

10 8

Jama Kuźnicka Klif Orłowski

June September

Cladophora glomerata

6

June

2012

1.4 0.7 1.3 0.008 1.6 0.5 2.3 0.014

1.1 0.5 0.8 0.001 1.3 0.5 0.7 0.003

1.6E 5.2E 1.2E 2.6E 1.8E 3.7E 2.1E 4.5E

+ + + + + + + +

04 04 03 03 04 04 03 03

21 10 10 0.18 24 7 18 0.31

Coccotylus truncatus

5

Rowy Klif Orłowski Jama Kuźnicka Słupsk Bank

Pb Cd Ni Hg Pb Cd Ni Hg

June September

2013, 2015

Coccotylus truncatus Furcellaria lumbricalis

8 19

June September

1.6 5.6 6.6 0.019 1.6 2.4 9.2 0.016

0.5 5.8 0.4 0.004 1.1 1.9 3.8 0.007

1.8E 4.0E 6.2E 6.1E 1.8E 1.7E 8.6E 5.2E

+ + + + + + + +

04 05 03 03 04 05 03 03

24 79 53 0.43 24 34 74 0.36

61

Klif Orłowski Jama Kuźnicka Słupsk Bank Rowy Słupsk Bank Klif Orłowski Klif Orłowski Jama Kuźnicka Słupsk Bank Rowy

Pb Cd Ni Hg Pb Cd Ni Hg

Pb Cd Ni Hg

7.6 3.7 7.2 0.037

8.7 3.3 4.6 0.013

8.6E 2.6E 6.6E 1.2E

+ + + +

04 05 03 04

112 53 57 0.82

Stuckenia pectinata

16

Jama Kuźnicka

Zannichellia palustris

16 12

Jama Kuźnicka

Pb Cd Ni Hg Pb Cd Ni Hg

2.0 1.9 1.4 0.022 2.3 2.8 2.3 0.021

2.0 1.9 0.7 0.012 2.3 2.7 1.9 0.010

2.2E 1.3E 1.3E 7.0E 2.6E 2.0E 2.1E 6.8E

+ + + + + + + +

04 05 03 03 04 05 03 03

29 27 11 0.49 34 40 18 0.48

21

Polysiphonia fucoides

80

19

June September October June September June September October June September

June September

2012, 2013, 2015 2010

2012, 2013, 2015 2010, 2013, 2014, 2015

2012, 2013, 2015

2008, 2009, 2010, 2013, 2014, 2015

2012, 2013, 2015

2010, 2013, 2014, 2015

2012, 2013, 2015 2013, 2015

2012, 2013, 2015

Please cite this article as: Zalewska, T., Danowska, B., Marine environment status assessment based on macrophytobenthic plants as bioindicators of heavy metals pollution, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.02.075

T. Zalewska, B. DanowskaMarine Pollution Bulletin xxx (2017) xxx–xxx

The maximal mean concentration of Ni (9.2 mg kg−1 d.w.) was found in F. lumbricalis, and lower – 7.2 mg kg−1 d.w. and 6.6 mg kg−1 d.w. – in the tissues of the other red algae P. fucoides and C. truncatus, respectively. Vascular plants and the remaining algae species accumulated Ni at the level of 1.3–2.3 mg kg−1 d.w. P. fucoides and F. lumbricalis showed the highest variability of Ni concentrations, which is in this case partly a result of the quantity of the analyzed samples. Mercury showed relatively the least content among the analyzed metals, though the maximal level of the mean concentrations (0.037 mg kg− 1 d.w.) was determined again in P. fucoides. Vascular plants contained ca. 0.020 mg Hg kg−1 d.w. and the minimal concentrations were determined in Ch. baltica (Table 2).

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As regards mercury, in most plant species CR values were of the order of 103 L kg−1, similarly to nickel. Only CR for P. fucoides reached values as high as 1.2 ∗ 104 L kg−1 (Table 2). Vascular plants revealed surprisingly high bioaccumulation efficiency towards mercury with S. pectinata having the CR of 7.0 ∗ 103 L kg− 1 and Z. palustris – 6.8 ∗ 103 L kg−1. CRs characterizing bioaccumulation efficiency of Pb fell in a narrow range between 1.6 and 2.6 ∗ 104 L kg−1, with an exception of P. fucoides showing again an higher value of 8.6 ∗ 104 L kg−1 (Table 2). Cadmium was unquestionably the element most efficiently bioaccumulated, with CR at the level of 105 L kg− 1; 1.4– 4.1 ∗ 105 L kg−1 in the case of red algae and 1.4–2.0 ∗ 105 L kg−1 in vascular plants (Table 2). Slightly lower CRs were determined for Cladophora spp. (3.7 ∗ 104 L kg−1) and Ch. baltica (5.2 ∗ 104 L kg−1). The magnitude of concentration ratios definitely proved the applicability of macrophytobenthic plants in the monitoring of marine environment pollution with heavy metals as an alternative to the direct concentration measurement in seawater.

3.2.2. Concentrations of heavy metals in seawater The concentrations of lead, cadmium, nickel and mercury in seawater to be applied in CR calculations were determined through literature survey (Table 3) (Pempkowiak et al., 2000, Dippner & Pohl, 2004, Saniewska et al., 2010). Heavy metal concentrations in seawater in the off-shore Baltic Proper regions and in the Gulf of Gdańsk were found at considerably uniform levels, hence sufficiently reliable to be applied in CR calculations. Finally, the following concentrations of metals in seawater were applied: Pb – 8.8 ∗ 10−5 mg L−1, Cd – 1.4 ∗ 10−5 mg L−1, Ni – 1.1 ∗ 10− 3 mg L− 1 (Pempkowiak et al., 2000) and Hg – 3.1 ∗ 10−6 mg L−1 (Saniewska et al., 2010).

3.3. Environmental quality standards - EQS The Environmental Quality Standards for each metallic element and each plant species (EQSMP) have been calculated with the formula: EQSMP ¼ CR EQSSW

3.2.3. Concetration ratio determined for macrophytoobenthic plants For the CRs values calculations, using the average concentrations of Pb, Cd, Ni and Hg in selected plant tissues (Table 2), as the most representative to calculate the concentration ratios, was found to be the most appropriate approach (Leal et al., 1997, IAEA, 2014). It has to be underlined that the order of magnitude of CR values determined for individual metals was the same in various plant species regardless of the depth of sampling or season. Nickel turned out to be characterized by the lowest CR values, of the order of 103 L kg−1 (Table 2), with Ch. baltica and Cladophora spp. showing relatively low bioaccumulation efficiency 1.2 ∗ 103 L kg−1 and 2.1 ∗ 103 L kg−1, respectively. The vascular plants were showing similar levels of CR, while the CR range in red algae was 6.2–8.6 ∗ 103 L kg−1, accordingly to the higher Ni concentrations in their tissues.

ð2Þ

In the formula EQSsw denotes Environmental Quality Standard for heavy metal in seawater; the EQSsw applied in calculations (Table 4) have been drawn from the Directive 39/2013 (Anon, 2013). The suggested approach was based on the fact that metal concentrations in plant tissues – particularly in macroalgae tissues – are directly related to the concentrations in seawater as a consequence of direct element assimilation from the environment, unlike e.g. in fish, which accumulate elements through feed (Kryshev & Ryabov, 2000, Smith et al., 2002). The annual mean metal concentrations in plant tissues were assumed the most trustworthy metrix to define the good environmental status. The annual mean concentrations reflect certain averaged level of pollution in the bioaccumulation process continuing throughout the active vegetation period (Zalewska, 2012a, Zalewska, 2012b, Zalewska, 2015). However, because of the observed seasonal changes in heavy metal

Table 3 Heavy metals concentrations in southern Baltic seawater. Location

Concentrations (literature data)

Gulf of Gdansk Baltic Proper Baltic Proper

Baltic Proper above halocline 5–75 m

Gulf of Gdansk (Osłonino)

Gulf of Gdansk (Gdynia)

Medm Min Max Śr

Med Min Max Med. Min Max

Concentrations (literature data with converted units)

Pb ng L−1 88 11 15

Cd ng L−1 14 13 11

– – –

Pb diss. nmol kg−1 0.07 0.008 0.898 0.098

Cd diss. nmol kg−1 0.115 0.054 0.196 0.116

Hg tot pmol kg−1 19.67 1.4 235 31.85

– – – – – –

Hg ng L−1 3.1 1.6 7.5 1.9 0.3 9.4

– – – – – –

Ni μg L−1 1.08 0.72 0.82

– – – –

– – – – – –

Pb mg L−1 8.8E-05⁎

References

1.1E-05 1.5E-05

Cd mg L−1 1.4E-05⁎ 1.3E-05 1.1E-05

Hg mg L−1 – – –

Pb mg L−1 1.5E-05 1.7E-06 1.9E-04 2.0E-05

Cd mg L−1 1.3E-05 6.1E-06 2.2E-05 1.3E-05

Hg mg L−1 4.0E-06 2.8E-07 4.7E-05 6.4E-06

– – – –

– – – – – –

Hg mg L−1 3.1E-06* 1.6E-06 7.5E-06 1.9E-06 3.0E-07 9.4E-06

– – – – – –

– – – – – –

Ni mg L−1 1.1E-03⁎ 7.2E-04 8.2E-04

Pempkowiak et al. 2000

Dippner & Pohl, 2004

Saniewska et al., 2010

Values in bold were applied for calculations. Med – median. Min – minimum. Max – maximum. ⁎ Values taken for CR calculations.

Please cite this article as: Zalewska, T., Danowska, B., Marine environment status assessment based on macrophytobenthic plants as bioindicators of heavy metals pollution, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.02.075

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T. Zalewska, B. DanowskaMarine Pollution Bulletin xxx (2017) xxx–xxx

Table 4 Integrated EQS values for Pb, Cd, Ni and Hg in macrophytobenthic plants.

EQSSW Mean EQSMPL Median EQSMPL Final EQSMPL

mg L−1 mg kg−1 d.w.

Pb

Cd

Ni

Hg

0.0013 26 26 26

0.0002 33 37 33

0.0086 32 36 32

0.00007 0.41 0.43 0.4

concentrations in plant tissues the strict observance of time regime in plant sampling is strongly recommended (Carlson & Erlandsson, 1991, Haritonidis & Malea, 1995, Szefer, 2002, Zalewska, 2012a, 2012b). It means in practice that monitoring based on macrophytobenthic plants as bioindicators should be conducted at the same time of the year. Nonetheless, the macrophytobenthic plants can be applied in assessment under accidental situations as well. As anticipated, once of the highest values of EQSMP were determined in P. fucoides: 112 mg kg−1 d.w. for Pb, 53 mg kg−1 d.w. for Cd, 57 mg kg−1 d.w. for Ni and 0.82 mg kg−1 d.w. for Hg (Table 2). Cadmium showed higher EQSMP value (79 mg kg−1 d.w.) in C. truncatus, and relatively high (40 mg kg−1 d.w.) in Z. palustris, while Cladophora spp. and Ch. baltica were characterized by fairly low EQSMP, 7 mg kg−1 d.w. and 10 mg kg−1 d.w. respectively. In the case of lead, the EQSMP in individual species were quite uniform, except for P. fucoides, and fell within the range 21–34 mg kg−1 d.w. Taking into account considerable spreading of the individual metal concentrations in plant tissues and relatively small differences between their corresponding EQSMP values, which were calculated from derived mean concentrations, it seemed reasonable to determine uniform threshold levels for each of metallic elements defining the good environmental status for all analyzed species (Table 4). In the target EQSMP determination both the mean and median values were considered (Table 4) and, assuming prudent approach, it was decided that the good environmental status is achieved if the concentrations of Pb, Cd and Ni in plant tissues do not exceed 26 mg kg−1 d.w., 33 mg kg−1 d.w. and 32 mg kg−1 d.w. respectively, while in the case of mercury the threshold is set at 0.4 mg Hg kg−1 d.w. (Table 4). The EU Directive 39/2013 on Priority Hazardous Substances is setting EQS value for Hg at 20 μg kg−1 w.w. for biota. This value corresponds to 0.13 mg kg−1 d.w. for P. fucoides when recalculated to dry weight content, which in this case is ca. 15%. Hence, it can be seen that the experimentally determined EQSMP for Hg (0.4 mg kg−1 w.w.) and the one recommended

by the Directive are similar. Unfortunately, the Directive did not set the EQS values for the other metals. The Swedish Environmental Protection Agency is recommending reference values of the three heavy metals – Pb, Cd and Ni – in Fucus vesiculosus as follows: 0.9 mg Cd kg−1 d.w., 0.3 mg Pb kg−1 d.w. and 3.5 mg Ni kg− 1 d.w.; no value for Hg was determined (SEPA, 2000). These reference values are lower than the ones presented by our study, however, the methodology was different as they were determined as the fifth percentile of the data series. 3.4. Environment status assessment The requirements set by the EU Water Framework Directive (Anon, 2000) and by the Marine Strategy Framework Directive (Anon, 2008) in regards to monitoring and status assessment of biotic as well as abiotic elements of the marine environment with respect to hazardous substances could be well met by applying the presented bioindicator method. The determination of heavy metal concentrations in plant tissues could complement or even form an alternative for heavy metal monitoring in seawater carried out in coastal, transitional and offshore water bodies, where the determined EQSMP values make the assessment possible by calculating Contamination Ratios (CnR) (Eq. (3)). Contamination ratio is calculated by relating the concentrations of selected heavy metal measured in plant tissue at present (CMP) to the EQSMP. The classification based on CnR could extend to five classes: 0 b CnR b 0.5 – very good status, 0.5 b CnR b 1.0 – good status, 1.0 b CnR b 5.0 – moderate status, 5.0 b CnR b 10.0 – poor status and CnR N 10.0 – bad status. CnR ¼

CMP EQSMP

ð3Þ

In the presented study the four sampling areas (Fig. 2) have been characterized by calculating mean concentrations of Pb, Cd, Ni and Hg in various macorphytobenthic plants. By relating the resulting mean concentrations to EQSMP values CnR ratios were obtained. The CnR values classified the areas as having good or very good status with respect to all analyzed metals (Fig. 2), which corresponds to a good chemical status according to the WFD and to good environmental status (GES) according to MSFD. The presented method of environmental status assessment could serve multipurpose applications regarding the MSFD requirements for criteria and descriptors relaying on biological

Fig. 3. Schematic presentation of multiple applications of macrophytobenthic plants in MSFD assessment system.

Please cite this article as: Zalewska, T., Danowska, B., Marine environment status assessment based on macrophytobenthic plants as bioindicators of heavy metals pollution, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.02.075

T. Zalewska, B. DanowskaMarine Pollution Bulletin xxx (2017) xxx–xxx

elements, like D1 – biodiversity, D5 – eutrophication and D6 – sea floor integrity (Anon, 2010). The sampling of macrophytobenthic plants is carried out according to HELCOM COMBINE Manual (HELCOM, 1997), securing thus the repeatability of sampling and the method quality assurance. Following the taxonomic determination and biomass measurement, the dedicated plant species could be selected for heavy metal analyses carried out for the environmental status assessment within descriptor D8 (Fig. 3). 4. Conclusions

1. Seven specific macrophytobenthic plant species, fulfilling the requirements of bioindicators, were identified in the four Polish marine areas; three representing the red algae – Polysiphonia fucoides, Furcellaria lumbricalis and Coccotylus truncatus, two vascular plants – Stuckenia pectinata and Zanichellia palustris, chlorophyta – Cladophora spp. and a charophyta – Chara baltica. The properties taken into account were the efficiency of heavy metal accumulation, frequency of occurrence and biomass. 2. The measurements of heavy metal - Pb, Cd, Ni and Hg – concentrations in the selected plant tissues, carried out between 2008 and 2015, have shown considerable differences in metal concentrations even within one species depending on the sampling depth and season, this defining the plant biomass, the key parameter affecting bioaccumulation efficiency. 3. The averaged metal concentrations in plant tissues and data on their concentrations in seawater, taken from literature, served to calculate concentration ratios (CR), which turned out to attain very high levels: 104 L kg−1 for Pb, 103 L kg−1 for Ni and Hg and 105 L kg−1 for Cd. 4. The Environmental Quality Standards (EQSMP) determined from CRs and EQS values in seawater varied in relatively wide ranges: 21– 112 mg kg−1 d.w. for Pb, 7–79 mg kg−1 d.w. for Cd, 10–74 mg kg−1d.w. for Ni and 0.18–0.82 mg kg−1 d.w. 5. Finally, assuming precautionary approach, the good environmental status could be assessed if Pb, Cd, Ni and Hg concentrations in plant tissues were below 20 mg kg−1 d.w., 33 mg kg−1 d.w., 32 mg kg−1 d.w. and 0.4 mg kg−1 d.w. respectively. 6. The selected plant species with the corresponding EQSMP values can be well applied in environmental assessment systems regarding both WFD and MSFD requirements. References Anon, 2000. Directive 2000/60/EC of the European Parliament and the Council Establishing a Framework for Community Action in the Field of Water Policy. Anon, 2008. Directive 2008/56/EC of the European Parliament and of the Council of 17 June 2008 Establishing a Framework for Community Action in the Field of Marine Environmental Policy (Marine Strategy Framework Directive). Anon, 2010. Commission Decision 2010/477/EU of 1 September 2010 on Criteria and Methodological Standards on Good Environmental Status of Marine Waters. Anon, 2013. Directive 2013/39/EU of the European Parliament and of the Council of 12 August 2013 Amending Directives 2000/60/EC and 2008/105/EC as Regards Priority Substances in the Field of Water Policy. Babut, M., Corinne, B., Marc, B., Patrick, F., Jeanne, G., Geneviève, G., 2003. Developing environmental quality standards for various pesticides and priority pollutants for French freshwaters. J. Environ. Manag. 69, 139–147. Bondareva, L., Vlasova, I., Mogilnaya, O., Bolsunovsky, A., Kalmykov, S., 2010. Microdistribution of 241Am in structures of submerged macrophyte Elodea canadensis growing in the Yenisei River. J. Environ. Radioact. 101, 16–21. Burger, J., Gochfeld, M., Kosson, D.S., Power, C.W., Jewett, S., Friedlander, B., Chenelot, H., Volz, C.D., Jeitner, C., 2006. Radionuclides in marine macroalgae from Amchitka and Kiska Islands in the Aleutians: establishing a baseline for future biomonitoring. J. Environ. Radioact. 91, 27–40. Burger, J., Gochfeld, M., Kosson, D.S., Powers, C.W., 2007. A biomonitoring plan for assessing potential radionuclide exposure using Amchitka Island in the Aleutian chain of Alaska as a case study. J. Environ. Radioact. 98, 315–328. Carlson, L., Erlandsson, B., 1991. Seasonal variation of radionuclides in Fucus vesiculosus L. from the Öresund, Southern Sweden. Environ. Pollut. 73, 53–70. Carlson, L., Holm, E., 1992. Radioactivity in Fucus vesiculosus L. from the Baltic Sea following the Chernobyl accident. J. Environ. Radioact. 15, 231–248.

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Please cite this article as: Zalewska, T., Danowska, B., Marine environment status assessment based on macrophytobenthic plants as bioindicators of heavy metals pollution, Marine Pollution Bulletin (2017), http://dx.doi.org/10.1016/j.marpolbul.2017.02.075