What are Water Trucks and How It Can Benefit Your Business Operation

Water truck for transporting trailers or shipping materials it differs from other &#;heavy-duty&#; trucks used. The typical water truck that houses pumping equipment contains specially designed tanks to store large volumes of liquid. The job of water trucks is to carry water to industrial workplaces and spray water to add moisture to the soil. Water trucks also serve as preventative equipment to increase construction site safety where the risk of fire is common.

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We carry out extensive maintenance to keep the rental water tankers in our fleet performing under the most intense working conditions. You can safely rent the water trucks in our inventory for use for a day, a few weeks or longer, depending on your needs.

 

 

Water Truck Rental

 

Renting a water truck from Teknik Tanker can serve many valuable purposes. If you are working on a special outdoor project in hot and dusty environments, water trucks can provide dust suppression that will improve air quality for your workforce. The mining and construction industries are prime examples of industries that could benefit from the water truck application. Water trucks can prepare a surface for steam rollers at a job site by adding moisture to loose soil prior to rolling.

 

In addition to serving as standby fire suppression units at temporary job sites, water trucks can play a more active role by supplying fire trucks when fighting a large wildfire. Water trucks can wet dry areas as a precautionary measure in fire prone areas. During periods of low rainfall, water trucks can be used to keep trees and vegetation moist. Finally, water trucks; It can help fill tanks and reservoirs that serve as water sources for washing, cement mixing and similar industrial operations.

 

3.1

&#;Chemical characteristics of PM

2.5

in different road segments

Figure 2 compares the differences in the chemical composition of PM2.5 collected in the air spray road segment and ground aspersion road segment. The mass fraction of WSOM was the highest regardless of the weather and road section where the samples were collected, which accounted for 30&#;%&#;40&#;% of the total water-soluble components (Fig. 2a&#;d). From 23 to 25 March, the mass concentrations and fractions of WSOM (WSOC) were higher on the air spray road segment than on the ground aspersion road segment. For the case without water spray treatment (as a reference group), the chemical compositions of PM2.5 samples collected from those two adjacent road segments only showed small differences in concentration (Fig. 2d, h, i). It suggested that the impact of background PM2.5 or the meteorological factor on PM2.5 composition or level was similar between these two study sites. Obviously, the variations in the mass concentrations and fractions of WSOM from the air spray road segment to the ground aspersion road segment can be attributed to the differences in water-soluble SOA yield or formation pathway caused by different water spray treatments.

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The mass concentrations of ALW, WSOC and WSON tended to decrease from the air spray road segment to the ground aspersion road segment (Fig. 2e&#;g). Moreover, linear regression analysis showed that the mass concentrations of ALW (n=&#;8) were significantly positively (P&#;<&#;0.01) correlated with those of WSOC and WSON, with R2 values of 0.84 and 0.75, respectively. The results were consistent with those obtained by previous studies conducted in an agricultural area in Italy (Hodas et al., ) and a suburban forest site in Tokyo (Xu et al., b). Moreover, these studies by Hodas et al. () and Xu et al. (b) suggested that the ALW dependence of reactive gas uptake and subsequent aqueous reactions significantly contributed the production of WSOC and WSON. Thus, the increase in ALW concentration after air spraying can promote the formation of water-soluble organic compounds in PM2.5 in the road environment.

Nitrate and sulfate were the most abundant inorganic components (Fig. 2a&#;d), which have been identified as typical factors controlling ALW (Hodas et al., ). From the air spray road segment to the ground aspersion road segment, the decrease in nitrate concentration was more significant than that in sulfate concentration (Fig. 2i&#;k). Moreover, the concentration of nitrate significantly correlated with that of ALW (P&#;<&#;0.01, R2=&#;0.7). In contrast, the sulfate did not show a strong correlation with ALW (R2=&#;0.3). As we know, the gas-phase oxidation of NO2 by hydroxyl radical (&#;OH) to form nitric acid (HNO3) is an important pathway for the formation of daytime nitrate aerosol (Fu et al., ; Chen et al., ). Hydroxyl radical can be rapidly produced by O3 photolysis under conditions with abundant water vapor and sunlight (as in this study) (Li et al., ), which is undoubtedly beneficial to the production of HNO3. Thus, in the region with large NOx and ammonia emissions (originating from vehicle exhausts; Yang et al., ), the formation of daytime nitrate aerosol could be promoted by enhanced RH (24&#;%&#;43&#;% increase) after air spraying. This is also partly supported by the thermodynamics of ammonium nitrate formation (Mozurkewich, ; Hodas et al., ). Additionally, it has been suggested that the formation of nitrate and ALW is mutually reinforcing (Chen et al., ). Thus, the increase in ALW concentration after air spraying was mainly driven by RH and locally (traffic emissions) formed nitrate aerosol.

Interestingly, Ca2+ and Mg2+ showed a significant increase in concentration from the air spray road segment to the ground aspersion road segment (Fig. 2i&#;k), which was contrary to the case of other components (e.g., WSOC, ALW and nitrate). In addition, during 26 March without water spray treatment, the differences in both Ca2+ and Mg2+ concentrations between those two adjacent road segments were almost negligible (Fig. 2l). It is well known that Ca2+ and Mg2+ are typical crustal materials and are mainly enriched in atmospheric coarse particles (Chen and Chen, ). Thus, a decrease in Ca2+ and Mg2+ concentrations after air spraying implied that the water mist sprayed by mist cannon trucks had a better effect on suppressing road dust than the ground aspersion by traditional sprinkling trucks.

3.2

&#;Molecular characteristics of water-soluble organic compounds

Thousands of molecular formulas (&#;) were observed in WSOM in PM2.5 collected from the road environment (Table 1). The CHO molecular formulas (&#;) accounted for 20&#;%&#;25&#;% in all molecular formulas. Further, CHO compounds were classified according to the number of oxygen atoms in their molecules. The subgroups ranged from O2 to O15 (Fig. 3). The number and intensity of dominated O5&#;O10 subgroups accounted for 72&#;%&#;85&#;% and 71&#;%&#;86&#;% of the total compounds, respectively; moreover, these percentages were higher than the results reported for aerosols in Beijing (Xie et al., ). The average H/C and O/C ratios of CHO compounds varied from 1.08 to 1.24 and from 0.42 to 0.49, respectively (Table S1). The average O/C ratios were higher than the value (0.33&#;±&#;0.11) obtained from urban aerosols (Beijing, China), while the H/C ratios showed relatively small differences between our results and observation results in Beijing (1.14&#;±&#;0.37; Xie et al., ). In addition, another study performed in Beijing showed that the average O/C and H/C ratios of organic aerosols were in the range of 0.47&#;0.53 and 1.52&#;1.63, respectively (Hu et al., ). These dissimilarities might be attributed to the fact that the sources of urban aerosols are more complex than those of aerosols collected from road environments.

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The average H/C and O/C ratios of CHON compounds ranged from 1.05 to 1.21 and 0.42 to 0.51, respectively (Table S1). The H/C ratio ranges of CHON compounds in this study overlapped with those measured in previous studies (Su et al., ; Xie et al., ). However, the O/C ratios of CHON compounds were relatively higher in road-derived aerosols than in aerosols (0.36&#;±&#;0.12) or snow (0.32&#;0.37) collected in urban areas (building roof; Su et al., ; Xie et al., ). This difference might be associated with the influence of source strength (e.g., vehicle exhausts) and atmospheric oxidation capacity. The number of CHON formulas (&#;) was much higher than that of CHO formulas (Table 1). The assigned CHON formulas were further divided into CHON1 (N1O2&#;N1O16), CHON2 (N2O2&#;N2O13) and CHON3 (N3O2&#;N3O13) groups (Fig. 3). CHON1 was found to be the dominant nitrogen-containing species in all samples, which was consistent with previous reports on urban aerosols and snow (Su et al., ; Xie et al., ). Moreover, the CHON1 compounds with O/N&#;>&#;2 contributed 99.2&#;%&#;100.0&#;% to total CHON1 species in all samples. The CHON2 compounds with O/N&#;>&#;2 accounted for 90.2&#;%&#;100.0&#;% of total CHON2 species. For the CHON3 group, the proportion of nitrogen-containing compounds with O/N&#;>&#;2 was 53.0&#;%&#;61.8&#;%. The CHON species with O/N&#;>&#;2, which allows an assignment of oxidized-form nitrogen, are preferentially ionized in negative electrospray ionization mode (Lin et al., ; Su et al., ). Studies on the compositions of organic matter in urban rainwater and aerosols have suggested that numerous CHON compounds contained oxidized nitrogen function groups (e.g., &#;ONO2) and that NOx-related oxidation processes can be responsible for the formation of these CHON compounds (Altieri et al., ; Lee et al., ). Thus, the CHON compounds with O/N&#;>&#;2 in our PM2.5 samples can be assumed to be mostly in an oxidized form (e.g., organic nitrates).

Figure 3 also shows the differences in the number of CHO and CHON species between the air spray road segment and ground aspersion road segment. The abundance of each On subgroup in CHO compounds considerably enhanced after air spraying, especially the subgroups of O5&#;O11. In contrast, the number of CHO species for these two cases without water spray treatment showed a smaller difference (Fig. 3d). In general, the total number of CHO compounds increased significantly after air spraying (Fig. 3 and Table 1). However, there was no significant change for the total number of CHO species between the two cases without water spray treatment. These findings implied that the increased ALW after air spraying can substantially contribute to the formation of CHO compounds with a more oxygenated state.

The number of CHON compounds decreased significantly from the air spray road segment to the ground aspersion road segment, a variation pattern of which was similar to that of CHO compounds (Fig. 3 and Table 1). Furthermore, the decrease in the number of molecules from the air spray road segment to the ground aspersion road segment was more remarkable for CHON1 compounds than for CHON2 compounds. In contrast, the variation in the number of CHON3 molecules after air spraying was less significant than that of CHON1&#;2 compounds. In addition, an insignificant change in the number of CHON compounds was found in PM2.5 collected in the two road segments without water spray (Fig. 3d). Thus, the increase in the number of nitrogen-containing compounds after air spraying indicated that the interactions among ALW, traffic-derived reactive nitrogen and ambient VOCs may play an important role in organic nitrogen compound formation in PM2.5. This consideration can also be partly supported by the result obtained by Xu et al. (b) in a suburban forest in Tokyo, Japan. The authors suggested that ALW is a key promoter for the formation of aerosol WSON through secondary processes associated with atmospheric reactive nitrogen and biogenic VOCs (Xu et al., b). For sulfur-containing compounds, their molecular numbers just showed a relatively small change after air spraying (Fig. S1). This suggested that the impact of ALW on sulfur-containing compound formation was weaker than that of ALW on the formation of CHO and CHON compounds in this road environment.

3.3

&#;CHO and CHON species formed under the influence of increased ALW

The molecular compositions of CHO compounds in PM2.5 in the van Krevelen diagram were scattered across wider ranges in the air spray road segment than in the ground aspersion road segment, particularly on the sunny days (24 and 25 March) (Fig. 4). Moreover, common CHO molecules accounted for 39&#;% (sunny day), &#;63&#;% (cloudy to sunny day) and 90&#;%&#;95&#;% of CHO molecules in PM2.5 collected from the air spray and ground aspersion road segments, respectively (Table 1). In contrast, common CHO molecules contributed 81&#;%&#;85&#;% of CHO molecules in PM2.5 collected from two road segments without water spray (I and II). These results can be explained by the increased molecular diversity caused by ALW-related atmospheric processes. It also implied the importance of photochemical reactions in CHO compound formation. Furthermore, the unique CHO compounds were identified between PM2.5 samples in the air spray road segment (or no water spray road segment, I) and the ground aspersion road segment (or no water spray road segment, II) (Fig. S2). On 23 and 24 March, the newly emerging CHO compounds after air spraying were dominated by unsaturated aliphatic-like and highly unsaturated-like compounds. However, both unsaturated-like species (unsaturated aliphatic-like and highly unsaturated-like) and aromatic-like species (highly aromatic-like and polycyclic aromatic-like) contributed significantly to the newly emerging CHO compounds after air spraying on 25 March when the ALW and traffic flow were higher than other days (Fig. S2). Obviously, the formation of those unique CHO compounds was closely associated with increased ALW.

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Figure 5 shows the OSc values of the identified unique CHO molecules. The OSc values of these CHO molecules were higher than those of primary vehicle exhausts (&#;2.0 to &#;1.9) (Aiken et al., ). The OSc values of the secondary organic aerosol formed via the reactions of anthropogenic and biogenic VOCs (e.g., isoprene, monoterpene, toluene, alkane and alkene) and oxidants (e.g., O3 and/or &#;OH) varied from &#;1.1 to +1.0 (Kroll et al., ; Y. Li et al., ), which was within the OSc value ranges of CHO molecules measured in this study. In addition, hydrocarbon-like organic aerosol (HOA), likely linked with primary vehicle exhausts (Sun et al., ), only accounted for less than 6&#;% of total unique CHO compounds (Fig. 5). Although it is difficult to classify all CHO molecules in Fig. 5, these identified unique CHO molecules can at least suggest that the water mist from air spraying can promote the formation of CHO compounds and increase their molecular diversity. As mentioned previously, there are dense trees on both sides of the road. Thus, these newly emerging CHO compounds can be largely attributed to secondary processes associated with the oxidation of vehicle exhausts and biogenic VOCs by O3 and/or &#;OH. In addition, we also observed increased oligomerization (e.g., methylglyoxal (C3H4O2) to form oligomers (C4-7H6-10O5) in particle phase) of CHO compounds after air spraying (Ma et al., ), particularly on 25 March, with a high ALW level and a large traffic flow (Fig. S3c). The overall results implied that the water mist sprayed by mist cannon trucks can indeed enhance the abundance and diversity of CHO compounds in PM2.5 via promoting gas-to-particle partitioning of gas-phase oxidation products of VOCs and subsequent aqueous-phase reactions.

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For CHON compounds, their molecular compositions were scattered across an increased range in the van Krevelen diagram after air spraying compared to the observations in the ground aspersion case (Fig. S4). This was also indicated by the relatively low proportion of common CHON molecules (45&#;%&#;55&#;%) in total CHON compounds for the cases with air spraying treatment (Table 1). Moreover, these newly emerging CHON molecules after air spraying showed a high diversity, as shown in Fig. S5. The group of CHON1 was the dominant nitrogen-containing compound in the identified unique CHON compounds. On 23 and 24 March, the main unique CHON compounds emerged during air spraying were unsaturated aliphatic-like and highly unsaturated-like nitrogen-containing species. The number of highly aromatic-like and polycyclic aromatic-like compounds that newly emerged also increased significantly following increased traffic flow and ALW (25 March). The results suggested that the increase in ALW concentration after air spraying can facilitate the formation of particle-phase nitrogen-containing compounds (Hallquist et al., ; Xu et al., b).

Organic nitrates have been supposed to be abundant in our PM2.5 samples collected from the road environment. It is well documented that atmospheric organic nitrates are primary, secondary and tertiary byproducts of reactions among anthropogenic and biogenic VOCs, atmospheric oxidants (e.g., O3 &#;OH, and nitrate radicals), and NOx (Lee et al., ; Yeh and Ziemann, ; Su et al., ). In addition, numerous organic nitrates are known as semivolatile compounds, which are able to partition between the gas and particle phases when they are oxidized or photolyzed (Bean and Hildebrandt Ruiz, ). Recently, an oxidation and hydrolysis mechanism associated with the formation of atmospheric organic nitrates has been proposed to interpret the potential origins or precursors of CHON compounds (Su et al., ). In this study, we found that 68&#;%&#;82&#;% of newly emerging CHON1 compounds after air spraying can be explained by oxidation (e.g., R1OH) and product (e.g., R1ONO2) pair proposed by Su et al. () (Fig. 6a&#;c). It indicated that these newly emerging CHON1 compounds after air spraying were largely derived from the transformation of CHO species under existence of NOx. A similar pattern was also observed in the newly emerging CHON2 compounds (Fig. S6). It should be pointed out that vehicle exhausts and roadside vegetation are important sources for VOCs and NOx in this road environment. However, the number of unique CHON1 and CHON2 compounds identified in the comparative cases without water spray treatment was much less than that identified in the comparative cases with air spraying and ground aspersion treatments (Figs. 6 and S6). In particular, we did not observe significant oligomerization of CHON compounds after air spraying (Fig. S7). Thus, these results suggested that the increase in ALW caused by air spraying can facilitate the formation of organic nitrates via CHO compounds as potential precursors under the presence of NOx.

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3.4

&#;Environmental implication

Mist cannon sprayers are commonly applied in agriculture for the distribution of fertilizers, pesticides and herbicides. In recent years, misting cannon trucks are widely developed and regarded as an excellent option for road dust control due to the production of tiny water droplets that can drop dust to the ground. In particular, it was a high-performance system for spraying disinfectant in the road environment during the COVID-19 epidemic period. For the first time, we provide a detailed characterization of chemical compositions in road-derived PM2.5 under the influence of air spraying. A recent study conducted in a rural site (Shanghai, China) has suggested that gaseous water-soluble organic compounds mainly partitioned to the organic phase (organic shell) under the condition of RH less than 80&#;% (relatively low ALW) but to ALW under the humid condition (RH&#;>&#;80&#;%, as air spraying operation), highlighting the importance of high ALW in SOA formation processes (Lv et al., ). This is because aerosols can exist in a phase-separated form with an inorganic core and an organic shell (Yu et al., ; W. Li et al., ; Ushijima et al., ). Our results verified the formation of numerous unique CHO and CHON compounds by ALW-related promoting effects (Fig. 7). In particular, the mass concentrations of WSOC in PM2.5 increased by 62&#;%&#;70&#;% after air spraying. Clearly, although the air spraying by mist cannon system could exert a better effect on suppressing road dust than the ground aspersion, as discussed previously, air pollution induced by increased water-soluble organic compounds in PM2.5 will be exacerbated in the road environment.

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To reveal the influence of air spraying on PM2.5 pollution on the roadside, we investigated the time series of percentage variation in road PM2.5 mass concentration after the mist cannon truck was operated at a low speed (<&#;30&#;km&#;h&#;1) (Fig. 8). It should be pointed out that the mist cannon truck was usually operated back and forth on specific road sections to prevent the resuspension of dust. After the misting cannon truck passed through the monitoring site several times, repeated online PM2.5 monitoring (n=&#;34, within a month) was performed to exclude the impact of dispersion and traffic flow on analysis results. Accordingly, the resuspension of road dust was expected to exert a relatively minor impact on the PM2.5 level near the road. The concentration of PM2.5 showed an increasing trend after the mist cannon truck passed through the monitoring point for 15&#;min. Thus, the water droplets sprayed by the mist cannon truck cannot directly cause an increase in PM2.5 concentration, suggesting that the increased PM2.5 should be secondarily formed after water mist spraying (&#;&#;15&#;min). This consideration was also supported by a significant increase in the concentration and number of water-soluble organic compounds after air spraying (Figs. 2 and 3). After the mist cannon truck has passed for 25&#;35&#;min, the increased proportion of PM2.5 concentration on the roadside gradually reached the maximum (&#;&#;13&#;%, on average). Subsequently, the proportion of increase in PM2.5 concentration gradually decreased, reaching &#;&#;6&#;% at 50&#;min after the mist cannon truck was operated. In addition, the width of the road segment (81 road, Nanchang, China) where PM2.5 was monitored is very large (&#;&#;43&#;m), implying that the water mist sprayed by mist cannon trucks should exert a greater promoting effect on the formation of PM2.5 on conventional urban roads. The overall results suggested that mist cannon trucks cannot effectively reduce the PM2.5 level in the road environment but lead to aggravation of PM2.5 pollution.

The chemical composition of fine aerosol particles in the urban road atmosphere is highly complex, including a lot of harmful organic compounds (e.g., polycyclic aromatic hydrocarbons and nitro-aromatics), as indicated by our measurements and a previous study (Tong et al., ). Emissions from vehicles and roadside vegetation are important anthropogenic and biogenic sources of reactive gas-phase OC and key precursors for forming SOA in urban areas (Gentner et al., ; Xu et al., b; Tong et al., ). In particular, organic aerosol composition in the road environment can be strongly impacted by vehicle emissions (e.g., VOCs and NOx) (Tong et al., ). Inhalation of the particles containing harmful organics can be responsible for a number of adverse health effects (Künzli et al., ). However, the wide application of mist cannon trucks by local environmental protection departments undoubtedly accelerates the formation processes of water-soluble organic compounds and PM2.5, which will further worsen the urban road environment and cause health hazards to walking residents. Thus, the present study provides crucial information for the decision makers to regulate the mist cannon truck operation in many cities in China.

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