THE UTILIZATION OF LICHEN AS BIOMONITORING NO 2 GAS EMISSION IN THE CITY OF PALEMBANG

This study aims to determine the type of lichen as a bioindicator of air pollution and its potential in biomonitoring NO 2 gas emissions in the air using the index of atmospheric purity (IAP) calculation method. The research area was divided into 4 sampling stations. One location is a motorised traffic-free area designated as station 1. Station 2, 3, and station 4 are areas located on roads with different motorised traffic densities. At stations 1, 2, 3 and 4, NO 2 pollutant levels were measured following the SNI 19 – 7119.2 – 2005 procedure with the Griess Saltzman method. Furthermore, at the same station, the pollution level was also determined by calculating the IAP value. Based on the IAP value, the pollution level at the research area station is in the low-very high category with NO 2 gas pollution levels in the range of 7.95 – 12.1 μg/Nm 3 /hour. There are 8 species of lichen whose presence can serve as bioindicators of NO 2 pollution in the air. These species are Graphis sp., Lecanora sp., Lepraria sp., Dirinaria sp., Graphis scripta, Canoparmelia sp., Ochrolechia sp., and Lecidella elaeochroma . The results of the average measurement of NO 2 levels show that NO 2 levels at the four sampling stations are still in a safe status because they are still below the air quality standards. The IAP value has a negative correlation with NO 2 levels in the air, where the higher the NO 2 levels in the air, the lower the IAP value, otherwise if the NO 2 levels in the air are lower, the IAP value will be higher. The Pearson Correlation test shows that there is a negative relationship (unidirectional relationship) between NO 2 levels in the air and IAP values. The higher the pollutants in an area, the lower the number of colonies and area of lichen cover on trees, especially in lichen species that are sensitive to air pollution.


INTRODUCTION
Palembang is South Sumatra Province's capital with a 1.38% growth rate in 2010-2020.In line with the increase in the population growth rate, the transportation sector in Palembang also increases.Consequently, it increasing exhaust gases from vehicles, the main source of air pollution in urban areas.The pollutant from vehicles causes various respiratory problems both acute and chronic caused by primary pollutants such as dust particulate (PM2,5 and PM10), ozone (O3), nitrogen dioxide (NO2), dioxide sulfur (SO2), carbon monoxide (CO), lead (Pb), and others (World Health Organization, 2011).There are number aspects coming up with the high levels of pollution and risks caused by vehicle gas emissions pollutants that entering the air makes air monitoring necessary.One of air quality monitoring techniques is biomonitoring by utilizing organism as indicators (Fandani, 2017).
Biomonitoring by utilizing plants as indicators is an alternative technique for more efficient air quality monitoring (Agnan et al., 2017).It can be done because vehicles exhaust gas emissions can interfere with the growth of plant such as plant structure, morphology, and biochemistry (Zulkifli, 2011) and one of organisms that can be used as air quality indicator is lichen.Lichen is very sensitive to air pollutants because it does not have a cuticle, so it absorbs the nutrition from the water and air directly.
The process happens when the pollutants absorbed into the thallus lichen tissues along with the process of absorption water and nutrition.Lichen cannot avoid the damage because lichen is not able to process and isolate the harmful pollutant rapidly (Brodo et al., 2001).Lichen does not have a mechanism for removing absorbed pollutants, so a change in the color of lichen thallus can identify pollutant accumulation (Ahmadjian et al., 1973).
The study about the relationship between pollutants and the growth of lichen had been carried out by Das et al. (2013) and the results showed that the number of lichen found in the research area had a direct relationship (positive correlation) with value of index of atmosphere purity (IAP).This article only focused on one of pollutant parts, NO2.NO2 is the primary pollutant that emitted from exhaust of motorized vehicles to human being health and environmental impact and it has been documented (National Expert Group on Transboundary Air Pollution (NEGTAP), 2001).NO2 has been known as pollutant whose concentration is more than the quality standard of urban air (Driejana & Handika, 2013).
The aim of this study was to find out the type of lichen bioindicator of NO2 gas pollutant and the potential use as a biomonitoring of NO2 gas emission in the air by using the value calculation method index of atmosphere purity (IAP).

MATERIALS AND METHODS
The tools and materials that were used in this research consisted of plastic size 30 x 10 cm as material for making quadrant plots, tusk pin to stick the plot on the tree, tally counter digital to calculate motorised vehicle density, measuring tape 150 cm to measure the tree diameter, thermohygrometer to measure temperature and humidity, digital camera for photo documentations, macro lens with diameter 25 mm to focus the object of this research, and a set of laboratory tools called impinger to collect airborne contaminants by bubbling the sampled air at a high flow rate through a method specific asbsorbing liquid inside.
Before determining the sampling area station, a survey was carried on the feasibility of a number of areas and roads in Palembang which was used as sampling station.The targets of survey included the presence of lichen, environmental temperature and humidity, the density of motorised vehicles (vehicles per hours) in each sampling station.Based on the results of survey, station 1 was located on a conservation forest area and free of motorised vehicles.Then, station 2 was located on a road with a density of traffic 291.3 vehicles/hours, station 3 on a road with a density of traffic 379.3 vehicles/hours and station 4 on a road with a density of traffic 459.5 vehicles/hours.In this study, it was assumed that the higher the traffic density, the more NO2 gas emissions are released in the air.Here is a description of each sampling station, station number 1= Nature uutilization area of Punti Kayu Palembang; station number 2= D. I. Panjaitan street; station number 3= POM IX street; and station number 4= Gubernur H.A Bastari street.
The determination of the sampling tree was carried out by observing the presence of lichen colonies on the tree.The tree selected at each sampling station was determined according to the criteria of Agnan et al. (2017), (1) a woody tree with lichen, (2) it has a similar bark structure, (3) the tree is protected from damage, (4) the size of the trunk circumference >40cm.The circumference of the tree was calculated by measuring the tree using a 150 cm tape measure.Based on the observations, 5 sampling trees were selected at each station.

The Measurement of NO2 Level
The measurement was carried out by taking the air sample by using the passive sampler method with a set of laboratory tools called impinger to collect airborne contaminants by bubbling the sampled air at a high flow rate through a method specific absorbing liquid inside.Then, the sample were analyzed spectrophotometrically about how to test nitrogen dioxide (NO2) levels with Griess Saltzman method according to the SNI 19-7119.2-2005procedure (Badan Standardisasi Nasional (BSN), 2005).

Lichen Data Collection
Lichen data collection on trees was carried out by placing four transparent plastic square plots that are placed at four different positions on the sample tree as high as ±1-1.5 meters from the ground (Agnan et al., 2017).The number of lichen species in the plot was counted and the area of colonies closure was measured.Lichen species identification was carried out by observing morphological characteristics such as color, shape, and type of thallus.

Lichen Identification
After the lichen data was collected, the data obtained were identified by using determination key on the website Lichen Determination Keys and the Ways of Enlichenment Lichen Photo Gallery.

Data Analysis
Data consisting of the number of lichens and the area of lichen colony cover were analysed to obtain data on the level of air pollution at each station by calculating the index of atmospheric purity (IAP) according to the formula of LeBlanc and De Sloover (1970) and the IAP criteria value of Conti and Checcetti (2001).Thus, the relationship between NO2 levels in the air and IAP values and the presence of lichens can be determined.The IAP value can be calculated based on the following formula.
n= total number of species; f= frequency; Q= ecological index.

RESULTS
Based on observations, there were 10 types of lichen was found.At the research site, 8 types of Crustose thallus consisted of Graphis sp., Canoparmelia sp., Ochrolechia sp., Lecanora sp., Lecidella sp., Arthonia sp., and Lepraria sp.The types of foliose thallus consisted of Dirinaria sp. and Canoparmelia sp.The presence, number of species and coverage of each type of lichen were shown in Table 2, the distribution of each species in each station was shown in Figure 1.

Index of Atmospheric Purity (IAP)
Table 3 below, shows that the value of index of atmospheric purity (IAP) at station number 1 was included in level D or low pollution category, station number 2 was included in level C or moderate pollution category, station number 3 was included in level B or high pollution category, and station number 4 was included in level B or high pollution category.The difference of IAP value depended on the presence of the lichen species, the number of colonies, and the closure area of each lichen species.These pollution categories are adjusted to the pollution categories according to Conti and Cecchetti (2001).

Pollution Level of NO2 in the Air
Air sampling was carried out at one point for each station.The air sample was analyzed spectrophotometrically by using Griess Saltzman method.The analysis of NO2 level referred to the SNI 19-7119.2-2005( Badan Standardisasi Nasional (BSN), 2005).The result of NO2 level analysis were shown in Table 4. Ambient air quality standard according to the government regulation Republic of Indonesia No. 22 year of 2021.The correlation between NO2 level and the value of IAP could be seen in Figure 1.NO2 level and IAP value negative or un-directional relationship, it meant that the higher the NO2 level the lower the IAP value was and vice versa.Similarly, the level of NO2 and the number of lichen colonies also had negative or un-directional relationship, the higher NO2 level the lower number of lichen colonies was, and vice versa (Figure 2).

DISCUSSION
Observations on the presence of species, number of colonies and area of lichen cover at each sampling station were made in order to obtain lichen data to calculate the IAP value.Based on the observation, there were 10 types of epiphytic lichen found as can be seen in Table 2.The lichens found belonged to 7 tribes, namely Calicaceae, Graphidaceae, Parmeliaceae, Ochrolechiaceae, Lecanoracea, Stereocaulaceae, and Arthoniaceae, with a total number of colonies of 1,031.At each sampling station, 5 trees were selected according to the sampling tree selection criteria.Based on the survey results, many lichens were found attached to several types of trees including mahogany (Swietenia mahagoni (L.) Jacq.), ashoka (Polyalthia longifolia (Sonn.)Thwaites.),flamboyant (Delonix regia (Hook.)Raf.), king palm (Roystonea regia (Kunth.)O.F.Cook.),saga (Adenanthera pavonina (Linn.)),and pulai (Alstonia scholaris (L.) R.Br.).
Based on the type of talus, the types of lichen found and dominate the four sampling stations are lichen with crustose talus type which in order with the highest number of colonies, namely Graphis sp., Canoparmelia sp., Ochrolechia sp., Lecanora sp., Lecidella sp., Arthonia sp., and Lepraria sp.The lichen with foliose talus type found are Dirinaria sp. and Canoparmelia sp.Lichen species with crustose talus type were found at each sampling station with varying environmental abiotic factors.According to Boonpragob (2003), lichen with crustose talus type belongs to the tolerant talus type compared to other talus types.The results in this study show the amount of presence of crustose talus type lichen species at each sampling station.Lichen have different levels of sensitivity to pollutants, tolerant lichens will survive in environments with high levels of pollutants compared to sensitive species (Kuldeep & Prodyut, 2015).The distribution of lichen species at each station can be seen in Table 2. Based on research conducted by Davies et al. (2006), Lecidella sp. is one of the lichen species whose sensitivity is at level 4 (scale: 1= tolerant, 10= sensitive).In accordance with this, the results of this study also show that Arthonia sp. is a species with sensitivity level 9.This is evidenced by the small presence of Arthonia sp.colonies at stations number 3 and number 4, where the values of NO2 levels at both stations is higher than the other stations.While the presence of Arthonia sp. was quite abundant at station number 2 with a total of 87 colonies.Basically, lichen will passively absorb nitrogen and other particulates in the environment as nutrients to survive.However, if too many pollutants are absorbed, it will cause excessive growth or "over-fertilize", and can even cause death in some sensitive lichen species (Oliver et al., 2011).
The index of atmospheric purity (IAP) value is determined based on previously obtained lichen data in the form of species presence, number of colonies and lichen cover area.Station number 1 is an area with the lowest pollution level among the other three stations, station number 2 (moderate pollution level), station number 3 (high pollution level), and station number 4 (high pollution level).Differences in IAP values depend on the presence of species, number of colonies, and area of cover of each type of lichen (Table 2).IAP value has a positive correlation with the number of lichen colonies, where the higher the number of lichen colonies, the higher the IAP value, indicating that the pollution is still in the category of that the pollution is still in the low category.
The air quality measurement with NO2 parameter was conducted during peak traffic hours with theair sampling frequency of two times with the analysis process in accordance with the procedures of SNI 19-7119.2-2005About how to test NO2 levels with the Griess-Saltzman method using spectrophotometry.Measurements were made by placing the impinger in an open field at a distance of ±500 m from the road body.The measured NO2 levels are then compared with the air quality standards contained in Government Regulation of the Republic of Indonesia No. 22 Year 2021.The results of the analysis of NO2 samples in the air can be seen in Table 4. Differences environmental factors at each sampling station may also can also affect the accumulation of pollutants in the air.Measurement of NO2 levels in this study were measured under conditions of high temperature and humidity due to rain.According to Sánchez et al. (2002), high values of pollutant concentrations are due to low relative humidity and the absence of precipitation, the value of pollutant levels becomes low.Air temperature can also affect the accumulation of pollutants in the air, because the higher air temperature will cause the air to become tenuous and lower pollutants (Sari et al., 2013).
In addition to temperature and humidity, the direction of wind speed is also a factor that affects the differences in NO2 levels in the air, as shown research by Çelik and Kadi (2007) which showed that pollutants can accumulate due to relatively slow wind speed, while few pollutants will accumulate due to relatively slow wind speed.While less pollutants will accumulate due to relatively fast wind speed.
Based on the previous explanation of IAP values and NO2 levels, it can be known that IAP values have a negative correlation with NO2 levels in the air which can be seen in Figure 1, where the higher the NO2 levels in the air, the lower the IAP value.Seen from Pearson-Correlation test results, it can be seen that there is a negative relationship (unidirectional relationship) between NO2 levels in the air and IAP values.

CONCLUSION
The calculation of index of atmosphere purity (IAP) value using lichen as a bioindicator was suitable as a method for determining the qualitative level of gas NO2 pollution in the air.The IAP value had a negative relationship with NO2 pollutant level in the air, but it had a positive relationship with the lichen presence.If the air in an area is polluted, it is possible that the number of colonies and the area of closure of lichen species will be increasingly especially for the species that are sensitive to air pollution.
This proved the assumption that the more gas emissions released into the air, the higher the level of air pollution.Meanwhile, the higher of pollutant in an area, the lower of number of colonies and the area of lichen coverage, especially in the type of lichen which is sensitive to air pollution.These results indicated that lichen can be a biomonitoring of NO2 gas emission.The factor that affected lichen function as a bioindicator was the sensitivity of lichen to the presence of pollutant.

Figure 1 .Figure 2 .
Figure 1.Correlation between the level of NO2 to the IAP value

Table 2 .
Presence, colony number, and closure area of lichen

Table 3 .
Index of atmospheric purity (IAP) at each sampling station

Table 4 .
Analysis result of NO2 pollutant in the air at each sampling stations