INTRODUCING A METHOD OF URBAN SOIL RISK EVALUATION – A CASE STUDY ON URBAN RECREATIONAL AREAS IN CLUJ NAPOCA

Assessing risks related to urban soil contamination represents a key part of pollution management. The current research proposes a quantitative method that defines and highlights unacceptable risks. The applicability of the method is presented in a case study on several urban recreational areas from the city of Cluj-Napoca, Romania. Concentrations of As, Cu, Cd, Zn, Pb, Hg, Co, Ni and Mg were identified in a number of 48 soil samples from 12 intensively used recreational areas in ClujNapoca. The proposed risk assessment method is applied, and potential risks are calculated for all locations.


INTRODUCTION
Risks posed by soil contamination have been the subject of analysis and evaluation due to the complexity of their assessment and the implications for public health issues [1].In order to manage soil contamination, protective levels and release standards have been set, and remediation methods have been applied in areas where soil contamination levels were found to exceed thresholds established through regulations.The interest of researchers in assessing soil contamination has been split between urban/industrial sites [2][3][4] and agricultural sites [5,6].In both cases risks have been discussed in terms of sources, pathways and receptors but due to the fact that contaminated sites were numerous, the need to prioritize their remediation has soon arisen and methods of assessing and scaling risks have been developed.
In scientific literature, risk assessment is defined as the process of estimating the potential impact of a chemical or physical agent on human health or on an ecological system under a specific set of conditions [7,8].Risk assessment methods vary and generally imply phases or qualitative and quantitative dimensions.They are adapted in regards with legislation, purpose of use, the degree of complexity and the expertise of the developers [9].International work groups and comities have studied differences in risk assessment approaches and have identified methodological general components and future improvement needs [10].CARACAS (Concerted Action on Risk Assessment for Contaminated Sites in the European Union), NICOLE (Network for Industrially Contaminated Land in Europe), ETC/S (European Topic Centre on Soil) and RACE (Risk Abatement Centre for Central and Eastern Europe) are concluding examples of international initiatives established for better handling soil contamination and related risk assessment.
Conclusions widely disseminated suggest that the use of more quantitative risk assessment approaches is needed, also taking into account that there is little interest for excessively detailed costly investigations in cases where conclusions are clear after a preliminary evaluation [10].Taking this into account, the current research proposes an easy quantitative method in order to objectively scale risks related to soil contamination with a particular focus on urban areas.The method has been adapted from the already existing BRGM -M.E soil risk assessment method designed in France by the Bureau of Geological and Mining Research, applicable to industrial contaminated areas and has been named "The Composite Method for Urban Soil Risk Evaluation".
Its purpose is to obtain a value that scales risks and highlights the unacceptable ones in an easily applicable manner, and it is designed to give preliminary results regarding the probability of risk existence.The Composite Method for Urban Soil Risk Evaluation takes into account several factors such as: identified contaminant concentrations, type and location of the analysed area, proximity to industrial structures, and intensive traffic nearby, absence of trees and green spaces and number of users.On this behalf, the method's results are based on site related information and should assist in decision-making for a more suitable urban environmental management.In order to present its applicability a case study of risk assessment on urban recreational areas from the city of Cluj-Napoca, Romania was conducted, and conclusions are discussed.

Case study location
In order to present the applicability of the Composite Method for Urban Soil Risk Evaluation, a Case Study was conducted on 12 recreational areas, (parks and playgrounds) situated in the city of Cluj-Napoca.
With a population of approximately 324.000 inhabitants, the city of Cluj-Napoca is considered the second largest city, after Romania's capital, Bucharest.Geographically, the city is situated in central Transylvania, between the Someşan Plateau, the Apuseni Mountains and the Transylvanian Plain.This area has been inhabited since ancient times due to its proximity to the Someş River and the moderate continental climate.Today, Cluj-Napoca is a well-known Romanian university centre, but over time industry has marked the city's economy.Companies activating in various industries such as chemical, pharmaceutical, cement manufacturing, engineering, ore extraction, abrasive products, cosmetics, textiles and clothing have conducted their activities influencing the city's environmental quality.Although, the urban land use planning has initially situated processing plants and factories on the outskirts of the city, the growing demand for housing led to the development of residential areas around the former industrial areas, encircling them.
Due to historical pollution and the process of contaminating retention and accumulation in soils, marks of industrial activities in Cluj -Napoca may be found in recreational areas top soils, posing risks to residential health.The present case study aims at identifying As, Cu, Cd, Zn, Pb, Hg, Co, Ni and Mg concentrations, in 48 soil samples from 12 such areas and analyses and scale risks using the Composite Method for Urban Soil Risk Evaluation.The risk assessment conclusions will be used for orientated urban environmental management practice suggestions.

Materials and methods
The 48 soil samples analysed in the present study were extracted during 1 st and 10 th of May 2013 from 12 locations (parks and playgrounds) situated in different parts of the city of Cluj-Napoca.The sampling locations were chosen based on their position, surface, importance and frequency of utilisation [1].Soil sampling was conducted based on the requirements stipulated in Order 184/1997 of the Ministry of Waters, Forests and Environmental Protection combined with recommendations within scientific profile publications.Additional precaution measures were taken during sampling and preparation in order to reduce sampling error [11] to limit external contamination and assure the integrity of existing contaminants [12].From every location 4 soil samples were collected, each sample being formed of a number of sub samples mixed together and reduced to the weight of 300 g.The soil extraction depth interval varied between 0-15 cm and sampling points were established, taking into account usability hotspots within playgrounds and parks (nearby swings, slides and sandboxes).
Soil samples were air dried for 24 hours, hammered to reduce agglomeration, redried using a drying stove at 110 o C, disintegrated and homogenised in a porcelain mortar and passed through 2 mm sieve in order to eliminate impurities.Soil samples less than 1 g were separated by repeated quartering [13] and acid digested.Concentrations of contaminants were identified using inductively coupled plasma mass spectrometry (ICP-MS).
Blank samples with standard reference materials were used for quality control.Summary statistics of the data obtained was structured in Table 1 and risks were calculated using The Composite Method for Urban Soil Risk Evaluation, described in detail in section 4.1.

The Composite Method for Urban Soil Risk Evaluation
The aim of the present research was to design and test a tool for risk evaluation, applicable for urban soils.The result is The Composite Method for Urban Soil Risk Evaluation, a quantitative method that responds to particularities encountered in urban areas.The base point used for elaborating it is the existing BRGM -M.E soil risk assessment method designed in France by the Bureau of Geological and Mining Research applicable on extended contaminated sites [14].The Composite Method for Urban Soil Risk Evaluation precludes the surface and ground water assessment but maintains the arithmetical formula and the parameters used in the BRGM -M.E method for soil assessments.The main adaptation consists in scaling the parameters used for calculating risk in order to comply with urban soil characteristics.The method is designed to give preliminary indications on the degree of risks posed by the soil in a defined area where the suspicion of contamination exists.
In order calculate the risk coefficient, eight distinct parameters are ranked, and a risk is calculated using the arithmetical formula Risk = (A+B+C) x (D+E+F+G+H).The parameters used in this calculation are: "A -Potential hazard", "B -Surface of the area", "C -Determined impact", "D -Existing sources of contaminants", "E -Protection barriers", "F -Access to contaminants", "G -Population" and "H -Type of population".A value from 0 to 3 is attributed based on a set of criteria assigned for each parameter.
Attributing a value to "A -potential hazard", Risk Phrases from Security Data Sheets for each contaminate under analysis are evaluated, in regard to their potential effect on human health or the environment.Special attention should be given to Risk Phrases such as R20: Harmful by inhalation, R21: Harmful in contact with skin, R22: Harmful if swallowed, R23: Toxic by inhalation, R24: Toxic in contact with skin, R25: Toxic if swallowed, R26: Very toxic by inhalation, R27: Very toxic in contact with skin, R28: Very toxic if swallowed, R36: Irritating to eyes, R37: Irritating to respiratory system, R38: Irritating to skin, R39: Danger of very serious irreversible effects, R40: Possible risk of cancer, R41: Risk of serious damage to eyes, R45: May cause cancer, R46: May cause heritable genetic damage, R48: Danger of serious damage to health by prolonged exposure and R49: May cause cancer by inhalation.Each applicable Risk Phrase for the contaminant under analysis is further ranked from 0 to 3 based on perceived gravity.An arithmetical mean between the values of the applicable risk phrases is calculated and results in the overall score for "A -potential hazard".In the final risk formula, this score will only be used if the concentration of the analysed contaminant exceeds the alert limit or the intervention limit established by national regulations.If the identified contaminant concentration exceeds the intervention limit, the potential hazard score should be used as it was calculated.If the concentration only exceeds the alert limit, the potential hazard score shall be divided by 2. If more contaminants are analysed the "A -potential hazard" score is calculated as the sum of all contaminates potential hazard scores.
"B -Surface of the area" must be ranked taking into account that an extended surface poses a greater risk to urban inhabitants.In this regard, a value of 1 is attributed to a surface less than 100m 2 , 2 for a surface between 100 m 2 and 10,000 m 2 and 3 for a surface that exceeds 10,000 m 2 .
The third parameter "C -determined impact" is evaluated based on identified contaminant concentrations compared to national regulations.0 is attributed if the concentration is situated below the value considered normal, 1 if the value exceeds normal thresholds but is maintained under the alert threshold, 2 if the identified value exceeds the alert threshold and 3 if the identified contaminate concentrations value exceeds the intervention threshold.
Parameter "D -Existing sources of contaminants" is evaluated based on the presumption that a greater number of contaminated sources situated around the investigated area represents an enhancer of risk [15].As a result, the value 0 is assigned if there are no potential sources of contaminates, 1 if there are potential contaminate sources but they are punctual and isolated and values of 2 or 3 shall be assigned when severe contamination sources are identified, and their presence may severely affect urban soil.
The fifth parameter "E -Protection barriers" takes into account the fact that an urban area that is isolated from trees or high buildings may be less affected by severe soil contamination [16].As a result, the value 0 can be assigned when the area under discussion is isolated by protection barriers, 1 if at least half of the area is isolated, 2 if less than a half is isolated and 3 if there are no protection barriers separating the area under discussion from contamination sources.
"F -Access to contaminants" is ranked based on the assumption that contaminates cannot produce unwanted effects if there is no contact with the receptor [17].Thus, the value of 0 is attributed if the soil is totally covered in concrete, grass, rubber or other material, 1 if the soil is mostly covered, and 2 or 3 when considerable surfaces of soil can come in contact with receptors.
Parameters "G -Population" and "H -Type of population" have a sociological valence."G -Population" refers to the number of urban inhabitants that come in contact with the soil from the area under discussion within an established unit of time [18].If an area is extensively used, it can be stated it poses an increased amount of risk [19] and therefore the value 0 is assigned if less than 10 persons come in contact with soil within the analysed area in a month's period, value 1 between 10 and 50 persons, value 2 between 50 and 150 persons and value 3 if more than 150 person come in contact with soil within the analysed area in a month's period.The type of population is also important for evaluating risks [20], and it is based on the concept of vulnerability [21].On this behalf, parameter "H -Type of population" can receive a value of 0 if the area under discussion is accessed only by adults, 1, if most of the visitors are adults of elderly persons, 2 if the population most frequently present in the area under discussion, is comprised of adults with children and 3 is it can be stated that most children alone accesses the area under discussion.
The purpose of the Composite Method for Urban Soil Risk Evaluation is to indicate the potential risk levels based on a calculated risk coefficient.The maximum obtainable coefficient depends on the number and type of contaminants included in the analysis and risks are divided into classes calculated proportionally using the maximum obtainable risk coefficient and the class thresholds stipulated in the initial BRGM -M.E method.After this, risks can be labelled as being acceptable, moderate and unacceptable, and this information may be further utilised in land use planning and risk management.

RESULTS AND DISCUSSIONS
The main descriptive statistics for the analytical results are highlighted in Table 1, together with normality, alert and intervention thresholds for Romania established through 756 Governments Order from 3 rd November 1997.Contaminant concentrations are expressed in mg/kg.As it can be seen in Table 1, mean contaminant concentrations exceed the normality threshold for As, Cu, Zn, Pb, Hg and Ni and the alert threshold for As and Pb indicating the presence of soil contamination in parks and playgrounds due to anthropogenic activities.Even through mean concentrations do not exceed intervention values, severe As, Pb and Hg punctual pollution was identified in 4 out of the 12 recreational areas analysed.These concentrations are very likely to be the consequence of formal industrial activities, due to the fact that three out of the four locations are situated in industrial areas.No major differences in terms of soil contamination can be indicated based on the type of the recreational area (park or playground).
In order to carry out the Composite Method for Urban Soil Risk Evaluation details regarding the analysed locations are necessary.Table 2 contains a codification of all 12 recreational areas, their location, type and a brief description.The abscissa represents the coding of the recreational areas and the ordinate the contaminate concentration expressed in mg/kg.Concentrations of Cd, Ni, Co and Mg do not exceed in any location the alert thresholds, and, therefore, have not been represented.
After analysing sampling location details and contaminate concentrations, identified risks were calculated using the Composite Method for Urban Soil Risk Evaluation.The method was implemented using an Excel tool to facilitate calculations and reduce the possibility of arithmetical errors when applying the formula:    Parameters as "A -Potential hazard", "B -Surface of the area", "C -Determined impact", "D -Existing sources of contaminants", "E -Protection barriers", "F -Access to contaminants", "G -Population" and "H -Type of population" were ranked taking into account specifications in section 2.1.
The maximum obtainable risk value is 255.Risks are divided into classes calculated proportionally using the maximum obtainable risk coefficient of 135 and the class thresholds at 55 and 30 as stipulated in the initial BRGM -M.E method.On this behalf, the Composite Method for Urban Soil Risk Evaluation identifies insignificant, acceptable risks with values between 1 and 57, moderate risks for calculated values of 58 to 103 and unacceptable risks from 104 to 255.Based on arithmetical calculations risks have been ranked accordingly and illustrated in Figure 6.
As it can be seen from Figure 6, the recreational area coded with CJ4 can be integrated with the unacceptable risk class due to soil contamination.The risk coefficient calculated for CJ4 is 104 due to the fact that this playground is situated in the industrial area, near a main street with intensive heavy traffic.Medium Cu, Pb and Hg concentrations exceed alarm thresholds, and the As concentration exceeds the intervention threshold.Moreover, access to contaminants is not restricted due to the fact that there is no grass or other material to limit it.A considerable number of individuals are using this playground, and the level of education, and the perception of risk are particularly low due to the fact that unattended children mostly use the playground.Fig. 6.Risk coefficients in the studied locations.
CJ3, CJ7 and CJ8 can be included in the moderate risk class.For CJ3 the risk coefficient is 84 due to extremely high values of As, Pb and Hg, but corroborated by the fact that not many inhabitants use this recreational area, risks posed to the resident's welfare are limited.CJ7 is a small size playground situated close to an industrial area, near a railway.The overall risk coefficient has a value of 95 taking into account the high accumulations of As, Cu, Zn, Pb and Hg in soil, the proximity to industrial structures and the lack of tree protection curtains.CJ8 has over 185 years old and is Cluj-Napoca's biggest park, having approximately 13.000 m 2 .The risk coefficient of 78 was calculated based on the identified medium concentrations of As, Zn, Pb and Hg corroborated with the large surface of the park and the extremely high number of the city's inhabitants that use this recreational area in their free time.
The parks and playgrounds coded with CJ1, CJ2, CJ5, CJ6, CJ9, CJ10, CJ11 and CJ12 are characterised by insignificant, acceptable risks due to their optimum maintenance.This strengthens the hypothesis that parks and playgrounds covered with grass, with tree curtains that limit access to contaminants, do not present notable risks to residential welfare.

CONCLUSIONS AND PERSONAL CONSIDERATIONS
Urban soil contamination in the city of Cluj-Napoca cannot be disregarded.Mean concentrations of arsenic and lead in recreational areas were found to exceed alert thresholds established through national regulations.This represents an alert signal due to the fact that the city of Cluj-Napoca is now a university centre and more than 20 years have passed since significant industrial activity has been conducted in the city's proximity.Taking this into account the situation of other cities in Romania in terms of soil contamination should be analysed as there is increased probability of extended pollution.
Moreover, the presence of soil contamination in recreational areas represents a threat to public health.In 9 out of the 12 urban recreational areas analysed the concentrations of As, Pb or Hg exceed normal reference values.Using Composite Method for Urban Soil Risk Evaluation one of the 12 recreational areas analysed (Cj4) was labelled as presenting unacceptable risks, while three other recreational areas (CJ3, CJ7 and CJ8) were included in the moderate risk class.An important matter of concern is that the main characteristics that describe Cj4 are representative for many neighbourhood playgrounds situated in the proximity of blocks of flats near industrial areas.Unfortunately, this type of land use planning is common in most of the Romanian cities.
By applying a risk assessment method, it was concluded that only 4 out of the 9 recreational areas with exceeded contaminate concentrations pose risks to public health, and only one recreational area would impose immediate remediation measures.These results prove that no all contaminated soil requires remediation methods as long as the risks involved are considered to be acceptable.Taking this into account it can be stated that the Composite Method for Urban Soil Risk Evaluation may be successfully used in environmental risk management procedures and may be introduced as a precaution step in urban land use planning.Environmental authorities of municipalities can apply it after contaminant measurements in soils where the presumption of diffuse pollution exists.Based on the results remediation measures can be applied accordingly, but taking into account the degree of uncertainty present when quantifying calculation parameters.In this regards the method proposed in the present paper can represent a useful tool in contaminated land management, as long as the environmental specialist applying the method is aware of its limitations and can provide relevant results when applied to quality input data.

Table 1 .
Descriptive statistics of analytical results for soil contamination.

Table 2 .
Details regarding the analysed recreational areas., 4 and 5 illustrate medium concentrations of As, Cu, Zn, Pb and Hg for all locations analysed, outlining with black the normality, with yellow the alert, and with red the intervention thresholds applicable in Romania.