Examining the changes in the amounts of PM2.5, PM10 and CO2 in the environment in debarking operations

MATERIAL AND METHOD

MATERIJALI I METODE

Study area - Područje istraživanja

This study was carried out in compartment number 9 located within the boundaries of Sarıyer Forest Management Directorate of Istanbul Regional Directorate of Forestry in Türkiye. Sarıyer Forest Management Directorate covers a total area of 10,543.8 ha, including 5,214.6 ha of forested area, 374.5 ha of unproductive area, 3,962.9 ha of open area, and 991.8 ha of private forests. Forest volume amounts to 217,291 m³, and the total wealth of the coppice forest volume is 49,055 m³. The total increment of the plan unit's forest is 10,646 m³, and the total increment of the coppice forest is 3,887 m³. The region is located between 41°08'13"-41°15'54" north latitude and 28°56'01"-29°06'59" east longitude (GDF 2023) (Figure 1). The size of compartment number 9, where the study was conducted, is 34.1 ha. The area cut within the compartment is a maritime pine (Pinus maritima Lam.) plantation.

Figure 1. Study area

Slika 1. Područje istraživanja

The study was conducted between June 2023 and July 2023. Two workers were involved in the debarking of the logs. The average slope of the land within the compartment varied between 2-12%. There was a dense ground cover in the cutting compartment. Therefore, the logs were removed from the compartment to the roadside landing with the help of a tractor, and the debarking process was carried out on the roadside. Three (3) m logs and 1.25 m industrial timber were the products produced in the compartment. During the study, the humidity of the air was 65% and the wind speed varied between 0 and 5 km/h. All cut trees were healthy and there were no dead standing trees or rotten trees among the cut trees. All logs on which debarking operations were carried out were produced from healthy trees.

Technical specifications of Husqvarna 365 chainsaw and Baseh debarking tool

Tehničke karakteristike motorne pile Husqvarna 365 i alata za otkoravanje Baseh

In the study, Baseh apparatus was used as for debarking (Figure 2) by being mounted on Husqvarna 365 chainsaw. The technical specifications of the chainsaw and Baseh debarking tool are shown in Tables 2 and 3 (URL-1; URL-2).

Table 2. Technical specifications of the Husqvarna 365 chainsaw

Tablica 2. Tehničke karakteristike motorne pile Husqvarna 365

Figure 2. Debarking apparatus

Slika 1. Alat za otkoravanje

Table 3. Technical specifications of the Baseh debarking apparatus

Tablica 3. Tehničke karakteristike alata za otkoravanje Baseh

Technical specifications of Temtop M2000 air quality meter

Tehničke specifikacije mjerača kvalitete zraka Temtop M2000

Temtop M2000 air quality meter (Figure 3) is a PM_2.5, PM₁₀, formaldehyde, CO₂, humidity, and temperature meter. General technical specifications of the device are shown in Table 4.

Figure 3. Temtop M2000 air quality meter

Slika 3. Mjerač kvalitete zraka Temtop M2000

Table 4. Technical specifications of Temtop M2000 air quality meter

Tablica 4. Tehničke karakteristike mjerača kvalitete zraka Temtop M2000

Methods – Metode

Data collection - Prikupljanje podataka

The study was carried out in the Sarıyer Forestry Management Directorate in the section numbered 9. Fifty-eight (58) coast pine logs (3 m length) were cut with a chainsaw and a study was carried out to evaluate the parameters affecting the debarking time. The diameter at mid length (d_0.5) of each timber was measured in centimeters (cm) and the length (l) was measured in meters (m). Huber's formula (2.1) (Carus 2002) was used to calculate the log volume using the mid diameter and log length. The debarking surface area (m²) S (2.2) and bark thickness (mm) were used to calculate bark volume (2.3) (Eker and Öztürk 2022).

[TeX:] V = \ \frac{\pi}{4}{{*(d}^{2}}_{0.5})*l$V=\frac{\pi }{4}{{*(d}^2}_{0.5})*l$ (2.1)

[TeX:] S = c*l$S=c*l$ (2.2)

[TeX:] B_{v} = S*Bt$B_v=S*Bt$ (2.3)

In the above equations, V is log volume (m³), d_0.5 (cm) is diameter at mid length of the log, c is circumference of the bark (m), S is debarking surface area of the log (m²), Bt is bark thickness (m), Bv is bark volume of the log (m³) and l is log length (m).

Field work method - Metoda rada na terenu

The air quality device was placed on the operator during debarking operations. The device was placed in a pocket on the reflective vest and positioned so as not to interfere with the operator's work (Figure 4). The device, which was continuously switched on during the debarking process, continuously measured the air quality at one-minute intervals. The data collected on Temtop M2000 was then transferred to the computer via a transfer cable and evaluated. During refueling and operator rest time, the device was left on the operator and measurements were continued.

Figure 4. Debarking work

Slika 4. Rad na otkoravanju

The values found during this study were compared with the air quality limit values in Table 1 in terms of their impact on human health.

Data analysis - Analiza podataka

Based on the characteristics of the data, the Kolmogorov-Smirnov test was applied. According to the Kolmogorov-Smirnov test results, Debarking time (sec) (Dt_sec), Work time (sec) (Wt_sec), Timber volume (V), Bark volume (m³) (Bv) and the features obtained with Temtop M2000 air quality meter (PM_2.5: Particulate matter of 2.5 microns and smaller, PM₁₀: Particulate matter of 10 microns and smaller, CO₂: Carbon dioxide, HCHO: Formaldehyde) were not normally distributed (p<0.05). The correlation between the properties was determined by considering Spearman’s correlation coefficient used for non-normally distributed data. Multiple regression models were developed using the backward selection method with the model shown in equation 2.4, where Dt_sec and Wt_sec were created as dependent variables and other attributes as independent variables. In addition, the assumptions of the regression analysis were examined and the autocorrelation problem of the regression model was determined by the Durbin-Watson (DW) value. DW value varies between 0-4, and if it is close to 2, it indicates that there is no autocorrelation problem (Kalaycı 2006).

[TeX:] Y\ = \ b_{0} + b_{1}X_{1} + b_{2}X_{2} + \ \cdots\ + b_{n}X_{n} + \ \varepsilon\ $Y=b_0+b_1{X}_1+b_2{X}_2+\cdots +b_n{X}_n+\epsilon$ (2.4)

Where b_i represent the model coefficients, Y is Dt_sec or Wt_sec, X_i (i = 1 to n) are texture values (B_v (m³), PM_2.5, PM₁₀, CO₂, HCHO and ε is the error term.

Data were separated to develop a model and to test the validity of the developed model. The model was developed with 75% of the data (43 of them). The other group comprising 25% of the data (15 of them) was used to test the validation of fitted models. The validity of multiple regression models where all parameter values were significant (p<0.05) was tested by the Wilcoxon signed rank test. The nonparametric Wilcoxon signed rank test was applied instead of student's t test because Dt_sec and Wt_sec were not normally distributed. Correlation analysis was obtained using the “metan” package in the R software program (R Core Team Citation 2019). IBM SPSS Statistics 29 software was used for the time prediction model and other statistical analyses. All tests were conducted at the significance level of p<0.05. The prediction success of the regression models was determined using Equation 2.5 Adjusted Coefficient of Determination (R²_adj), Equation 2.6 Mean Absolute Error (MAE) and Equation 2.7 Root Mean Square Error (RMSE), respectively.

Adjusted Coefficient of Determination (R²_adj);

[TeX:] R_{\text{adj}}^{2} = 1 - \frac{\sum_{i = 1}^{n}\left( Y_{i} - {\widehat{Y}}_{i} \right)^{2}(n - 1)}{\sum_{i = 1}^{n}\left( Y_{i} - {\overline{Y}}_{i} \right)^{2}(n - p)}$R_{\mathrm{\text{adj}}}^2=1-\frac{{\sum }_{i=1}^n{(Y_i-{\hat{Y}}_i)}^2(n-1)}{{\sum }_{i=1}^n{(Y_i-{\overline{Y}}_i)}^2(n-p)}$ (2.5)

Mean Absolute Error (MAE);

[TeX:] MAE = \frac{\sum_{i = 1}^{n}\left| Y_{i} - {\widehat{Y}}_{i} \right|}{n}$MAE=\frac{{\sum }_{i=1}^n|Y_i-{\hat{Y}}_i|}{n}$ (2.6)

Root Mean Square Error (RMSE);

[TeX:] RMSE = \sqrt{\frac{\sum_{i = 1}^{n}{\ \left( Y_{i} - {\widehat{Y}}_{i} \right)}^{2}}{n}}$RMSE=\sqrt{\frac{{\sum }_{i=1}^n{(Y_i-{\hat{Y}}_i)}^2}{n}}$ (2.7)

In these equations, ;[TeX:] \ Y_{i}$Y_i$,[TeX:] \ {\widehat{Y}}_{i}${\hat{Y}}_i$, [TeX:] {\overline{Y}}_{i}${\overline{Y}}_i$ are the measured, estimated and average values for the time study, n is the number of observations, and p is the number of parameters of the equation.

RESULTS AND DISCUSSION

REZULTATI I RASPRAVA

Descriptive statistical information of the measurements values and calculations made with the Temtop M2000 air quality device are given in Table 5.

Table 5. Descriptive statistics

Tablica 5. Opisna statistika

d_0.5: Mid diameter [TeX:] \left( \text{cm} \right)$\left(\mathrm{\text{cm}}\right)$, V: Timber volume [TeX:] (m^{3})$(m^3)$, c: Circumference (m), S: Debarking surface area (m²), Bv_: Bark volume (m³), PM_2.5: Particulate matter of 2.5 microns and smaller, PM₁₀: Particulate matter of 10 microns and smaller, CO₂: Carbon dioxide, HCHO: Formaldehyde, Dt_sec: Debarking time (sec), Wt_sec: Work time (sec)

When the international air quality limit values given in Table 4 are compared with the values found as a result of the measurements, it was found that the maximum values of PM_2.5, PM₁₀ and CO₂ (247 μg/m³, 411 μg/m³ and 2549 ppm, respectively) constitute a “Very Unhealthy” environment, while the average values for all three values (83.91 μg/m³, 121.69 μg/m³ and 614.19 ppm, respectively) are “Unhealthy” for PM_2.5 and “Moderate” for PM₁₀ and CO₂. The HCHO value was determined to be safe throughout all measurements and it does not pose a risk to human health. The “Very Unhealthy” PM_2.5 value indicates that forest workers working in debarking operations are in a risky working environment in terms of respiratory diseases. It has been reported in various studies that such high values pose a great risk for problems in the lower respiratory tract (Gülci et al. 2018; Baldauf et al. 2006). In cases where the PM_2.5 value is high, this value must be reduced (Martins and Graca 2018).

In this study, the debarking time of a timber was measured as Dt_sec between 45 and 273 seconds (sec) with a mean of 97.45 sec, and Wt_sec between 45 and 337 sec with a mean of 108.81 sec. When Dt_sec and Wt_sec values and tree characteristics were examined for their conformity to normal distribution by the Kolmogorov-Smirnov test, all values did not show normal distribution at 0.05 significance level, Therefore, Spearman’s correlation coefficient was used to determine the correlation coefficient. As a result of the correlation analysis, Dt_sec and Wt_sec values showed moderate positive correlations with Bv (m³) at 0.05 significance level, while PM_2.5, PM₁₀, CO₂ and HCHO did not show significant relationships. The significant relationships with Dt_sec and Wt_sec values respectively displayed were r = 0.604 and r = 0.575. The results are given in Figure 5.

Figure 5. Spearman's correlation analysis. Spearman's multiple correlation plot with R representing correlation coefficient and p the statistical significance (ns > 0.05;*p < 0.05;**p < 0.01; ***p < 0.001)

Slika 5. Spearmanova korelacijska analiza. Spearmanov dijagram višestruke korelacije gdje R predstavlja koeficijent korelacije, a p statističku značajnost (ns > 0,05;*p < 0,05;**p < 0,01;***p < 0,001)

In this study, with the help of backward regression, the parameters of the regression models in which Dt_sec and Wt_sec were used as dependent and other traits as independent variables were calculated and their prediction success was determined. The parameter equations and Durbin-Watson (DW) test statistic, R²_adj, MAE and RMSE values and other statistical measures for these equations are presented in Table 6. When Table 6 is analyzed, the goodness of fit of the models is analyzed by F test and the significance of the model coefficients is analyzed by t test, and all parameters of the models are found to be significant at 0.05 significance level. DW test statistic values for Dt_sec and Wt_sec models are 1.733 and 1.768, R²_adj values are 0.617 and 0.715, MAE values are 16.909 and 13.929, and RMSE values are 20.599 and 19.664, respectively.

Table 6. Regression analysis results

Tablica 6. Rezultati regresijske analize

ns: p>0.05, *: p<0.05, **: p<0.01, ***: p< 0.001

In order to check the validity of the models that were found to be successful according to the statistical criteria, with the help of the control data created by separating 15% of the data, the Wilcoxon signed rank test for paired samples (Wilcoxon signed rank test) compared the data obtained from the equations with the actual values and no statistical difference was found at the 0.05 level of significance (Table 7). Thus, it was decided that the established models were usable at 0.05 significance level.

Table 7. Wilcoxon signed rank test results for equations

Tablica 7. Rezulati Wilcoxonova testa ranka za jednadžbe

Z: Wilcoxon signed rank test, ns: p>0.05, *: p<0.05, **: p<0.01, ***: p< 0.001

As a result of the regression analysis (Table 6), the usable forms of the statistically successful D-1 and D-2 models are given below:

[TeX:] \text{Dt}_{\sec} = 48.32 + 1196.67B_{v} - 0.261\text{PM}_{2.5} + 0.030\text{CO}_{2}${\mathrm{\text{Dt}}}_{sec}=48.32+1196.67B_v-0.261{\mathrm{\text{PM}}}_{2.5}+0.030{\mathrm{\text{CO}}}_2$ (D-1)

[TeX:] \text{Wt}_{\sec} = 56.81 + 29080.29B_{v} - 0.356\text{PM}_{2.5} + 0.032\text{CO}_{2}${\mathrm{\text{Wt}}}_{sec}=56.81+29080.29B_v-0.356{\mathrm{\text{PM}}}_{2.5}+0.032{\mathrm{\text{CO}}}_2$ (D-2)

According to these findings, the debarking time of a timber is affected by the bark volume of the debarking log, CO₂ and PM_2.5 released during debarking. The temporal variations of PM_2.5, PM₁₀ and CO₂ values and their comparison with international threshold values are given in Figure 6, Figure 7 and Figure 8.

Figure 6. Temporal variation of PM_2.5 concentration

Slika 6. Vremenska varijacija koncentracije PM_2.5

Figure 7. Temporal variation of PM₁₀ concentration

Slika 7. Vremenska varijacija koncentracije PM₁₀

Figure 8. Temporal variation of CO₂ concentration

Slika 8. Vremenska varijacija koncentracije CO₂

There were two breaks during this study. The first break started at 15.15 and ended at 15.35 (20 minutes), and the second break started at 16.19 and ended at 16.52 (33 minutes). Measurements were taken continuously at one-minute intervals, including rest intervals. Changes were observed in the air quality measurements during the debarking operations (58 units). When the graphs in Figure 5, Figure 6 and Figure 7 are examined, it can be seen that PM_2.5, PM₁₀ and CO₂ values decreased and remained approximately stable during the rest periods shown in red. Especially in the CO₂ graph (Figure 7), where the red line remains approximately straight, the CO₂ rate in the environment is within the health limits. In the PM_2.5 and PM₁₀ graphs, minor peaks were observed at rest times. At the same time, looking at the last parts of the PM_2.5 and PM₁₀ graphs, it can be seen that the particle values are gradually increasing. This means that the particulate matter suspended in the air increases. In a similar study conducted in agricultural fields, Jia et al. (2023) reported that as the hours of operation of agricultural machinery in wheat fields increased, the particulate matter in the field also increased.

CONCLUSIONS

ZAKLJUČCI

During these debarking activities, measurements were made with Temtop M2000 air quality meter. PM_2.5, PM₁₀, CO₂ and HCHO values were measured throughout the debarking process and various values were found. Considering these values, it was determined that the average value of PM_2.5 is an “Unhealthy” environment when compared to international threshold values. The average values of PM₁₀ and CO₂ were found to be “Moderate” and the average value of HCHO was found to be “Safe”. It was observed that the maximum values of PM_2.5, PM₁₀ and CO₂ created a “Very Unhealthy” environment. The high PM_2.5 value indicates that particles of 1.0-2.5 microns in size are dense in the environment and that these particles may cause various disorders, especially in the lower respiratory tract of working people. It is known that if the PM₁₀ value increases from “Moderate” to “Unhealthy”, it may cause upper respiratory tract diseases. For this reason, work planning by considering these values is required for intensive debarking works. In the light of this study, the recommendations are listed below:

ACKNOWLEDGMENT

ZAHVALA

We would like to thank forest engineers Ergün Tuncer, Müslim May and Osman Kulaksız for their help during the preparation of this study.