Chloropicrin Research Articles

Seasonal Determination and Investigation of Disinfection by Product Formation Potentials (DBPFPs) of Surface Waters, İstanbul Ömerli and Büyükçekmece Case Study

All surface and ground waters include natural organic matter (NOM). During the disinfection NOM reacts with chlorine and forms various types of halogenated disinfection by-products (DBPs). There are lots of study in the literature about these possible carcinogenic effects on human. Trihalomethanes (THMs) and haloacetic acids (HAAs) are the most widely known and most produced DBPs. But there lots of different types of DBPs occurred after the disinfection and sometimes absorbable organic halogens (AOX) measurement can be used for determining the total amount of DBPs. In this study raw water samples were taken from Büyükçekmece (BC) and Ömerli (OM) surface water sources in the seasonal basis. At the first stage water quality parameters were analysed and then samples were chlorinated. After 7 days reaction period THMs, HAAs, haloasetonitrilles (HANs), chloral hydrate (CH), chloropicrin (CP) and AOX measurements were conducted and according to these results undefined DBPs percentage of AOX was calculated. In terms of OM and BC raw water undefined portion of AOX was averagely calculated as 59.4% and 58% respectively.

Application rate affects the degradation rate and hence emissions of chloropicrin in soil

Increasingly stringent regulations to control soil-air emissions of soil fumigants has led to much research effort aimed at reducing emission potential. Using laboratory soil columns, we aimed to investigate the relationship between chloropicrin (CP) application rate and its emissions from soil across a wide range of CP applications (equivalent to 56–392kgha−1). In contrast to the known behavior of other fumigants, total emission percentages were strongly and positively related to application rate (i.e., initial mass), ranging from 4 to 34% across the application rate range. When combined, data from a previous study and the present study showed good overall comparability in terms of CP application rate vs. emission percentage, yielding a second-order polynomial relationship with an R2 value of 0.93 (n=12). The study revealed that mass losses of CP were strongly disproportional to application rate, also showing a polynomial relationship. Based on degradation studies, we consider that a shorter half-life (faster degradation) at lower application rates limited the amount of CP available for emission. The non-linear relationship between CP application rate and CP emissions (both as % of that applied and as total mass) suggests that low application rates likely lead to disproportionally low emission losses compared with higher application rates; such a relationship could be taken into account when assessing/mitigating risk, e.g., in the setting of buffer zone distances.

Off-tarp emissions, distribution, and efficacy of carbonated fumigants in a low permeability film tarped field

Carbonated fumigants have been shown to distribute quickly and uniformly in sandy soils and improve pest control efficacy for annual crops. Low permeability films, such as VaporSafe® (TIF), could further improve fumigant dispersion by effectively retaining the fumigant in soil; however, there is a concern that the TIF can lead to higher off-tarp edge emissions. An orchard field trial was conducted to determine the off-tarp emissions, distribution, efficacy, and fate of carbonated Telone® C35 [63.4% 1,3-dichloropropene (1,3-D), 34.7% chloropicrin (CP)] that was shank-injected at 46cm soil depth. Treatments included carbonated fumigants at full- or 2/3 rates and a full rate of regular (nitrogen-pressurized) fumigants covered with standard polyethylene (PE) film, TIF, or no surface seal. Fumigant emissions at the regular tarp edge (25cm from the shank line) peaked at 3.98μgm−2s−1 for 1,3-D and 0.05μgm−2s−1 for CP. The addition of a TIF tarp extension (to 85cm from the shank line) reduce peak off-tarp emissions to <1 and <0.03μgm−2s−1 for 1,3-D and CP, respectively. Fumigant concentration under TIF was usually at least twice that under PE regardless of carbonation. Carbonation at 345KPa with 1.5% of dissolved CO2 did not significantly improve fumigant dispersion in soil profile compared to the conventional nitrogen pressurization. In a citrus nematode bioassay, only the 2/3 rate of carbonated fumigation treatment sealed with PE failed to control nematodes at 25cm away from shank line. This research indicates that a 60-cm TIF extension can effectively reduce off-tarp edge emissions in strip fumigation treatments. While the adaptability of carbonation of fumigants is still questionable, further research efforts are needed in finding effective solutions to control plant parasitic nematodes, which remain a challenge in orchard fumigation.

Effect of fumigation with chloropicrin on soil bacterial communities and genes encoding key enzymes involved in nitrogen cycling

Chloropicrin (CP) is a potential alternative for methyl bromide as a soil fumigant given that the use of methyl bromide has become limited. However, little is known about how fumigation with CP affects the condition of the soil microbial community. In this study, 16S rRNA amplicon sequencing and quantitative PCR were combined to investigate the effect of CP on soil bacterial community. In total, 938,922 effective reads were obtained from 18 samples and clustered into 58,662 operational taxonomic units at a similarity cut-off of 97%. Both approaches showed that the primary structure of bacterial community in soil did not significantly change at the phylum level after fumigation, but CP had a significant impact on the abundance of the bacterial microbiome that was recovered and identified. Additionally, bacterial community diversity decreased significantly, and there was a shift in the predominant populations. Staphylococcus, Actinomadura, Acinetobacter and Streptomyces significantly decreased in number or disappeared, and Bacteroides, Lachnoclostridium, Pseudoalteromonas, Colwellia, Idiomarina and Cobetia became the new predominant populations. In addition, some species associated with biodegradation, such as Sphingomonas spp. and Rhodococcus spp., significantly increased in number. The abundance of ammonia-oxidizing archaea (AOA) were significantly inhibited, yet the abundance of ammonia-oxidizing bacteria (AOB) significantly increased, and denitrification was significantly promoted. These changes in bacterial flora can considerably impact soil function and health and lead to negative effects on the environment surrounding fumigated soils, indicating the need for proactive risk management. Our study provides useful information for environmental safety assessments of CP in China.

Effect of Soil Fumigation on Degradation of Pendimethalin and Oxyfluorfen in Laboratory and Ginger Field Studies.

Herbicides are usually applied to agricultural fields following soil fumigation to provide effective weed control in high-value cash crops. However, phytotoxicity has been observed in ginger seedlings following the application of herbicides in fumigated fields. This study tested a mixture of herbicides (pendimethalin and oxyfluorfen) and several fumigant treatments in laboratory and field studies to determine their effect on the growth of ginger. The results showed that soil fumigation significantly (P < 0.05) extended the degradation period of these herbicides in the field and in laboratory studies. The half-life of pendimethalin was extended by an average of approximately 1.29 times in the field and 1.74 times in the laboratory. The half-life of oxyfluorfen was extended by an average of about 1.19 times in the field and 1.32 times in the laboratory. Moreover, the extended period of herbicide degradation in the fumigant and nonfumigant treatments significantly reduced ginger plant height, leaf number, stem diameter, and the chlorophyll content. The study concluded that applying a dose below the recommended rate of these herbicides in chloropicrin (CP) or CP + 1,3-dichloropropene fumigated ginger fields is appropriate, as application of the recommended herbicide dose in fumigated soil may be phytotoxic to ginger.

Effects of Biochar Amendment on Chloropicrin Adsorption and Degradation in Soil

The characteristics of biochar vary with pyrolysis temperature. Chloropicrin (CP) is an effective fumigant for controlling soil-borne pests. This study investigated the characteristics of biochars prepared at 300, 500, and 700 °C by michelia alba (Magnolia denudata) wood and evaluated their capacity to adsorb CP. The study also determined the potential influence of biochar, which was added to sterilized and unsterilized soils at rates of 0%, 1%, 5%, and 100%, on CP degradation. The specific surface area, pore volume, and micropores increased considerably with an increase in the pyrolytic temperature. The adsorption rate of biochar for CP increased with increasing pyrolytic temperature. The maximum adsorption amounts of CP were similar for the three biochars. Next, the study examined the degradation ability of the biochar for CP. The degradation rate constant (k) of CP increased when biochar was added to the soil, and k increased with increased amendment rate and pyrolysis temperature. The results indicate that biochar can accelerate CP degradation in soil. The findings will be instructive in using biochar as a new fertilizer in fumigating soil with CP.

Efficacy of chloropicrin application by drip irrigation in controlling the soil-borne diseases of greenhouse pepper on commercial farms in Poland

Three demonstration experiments were conducted on commercial greenhouse farms to assess the efficacy of chloropicrin (CP), applied by drip irrigation, in controlling Verticillium wilt and root rot disease complex of bell pepper, in comparison with dazomet at 40 g m−2. Chloropicrin was applied through drip irrigation system at 20, 30 and 40 g m−2 of emulsified commercial formulation. The concentration of CP in water was constant, and the required doses were obtained by delivering different amounts of the irrigation water per area unit (from 12.5 to 33 mm). The highest mean efficacy in reducing the inoculum density of Verticillium dahliae in the soil at all locations was obtained after CP application at 30 and 40 g m−2, about 85 and 86%, respectively. The number of viable microsclerotia recovered from the soil on the day of pepper planting was significantly correlated with the final incidence of Verticillium wilt disease (r = 0.962). The highest mean efficacy in controlling Verticillium wilt of pepper (86.4%) was obtained after soil treatment with CP at 40 g m−2, and ranged from 80.2 to 95.6%. The yield was stronger correlated with root rot severity (r = −0.849**) than with progression of Verticillium wilt, expressed by AUDPC (r = −0.651**). The dominant soil-borne pathogen responsible for pepper root rot was Colletotrichum coccodes. All chemical treatments provided a significant reduction in root rot severity compared to the untreated control. On-thefarm evaluation revealed that soil fumigation with drip-applied chloropicrin presents a feasible option for pepper growers.

Impacts of ferrate oxidation on natural organic matter and disinfection byproduct precursors

This study investigated the effectiveness of ferrate (Fe(VI)) oxidation in combination with ferric chloride coagulation on the removal of natural organic matter (NOM) and disinfection byproduct (DBP) precursors. Twelve natural waters were collected and four treatment scenarios were tested at bench-scale. Results showed that intermediate-ferrate treatment (i.e., coagulation and particle removal followed by ferrate oxidation) was most effective followed by pre-ferrate treatment (i.e., ferrate oxidation followed by coagulation and particle removal (conventional treatment)) or conventional treatment alone (i.e., no oxidation), and the least effective was ferrate oxidation alone (i.e., no coagulation). At typical doses, direct ferrate oxidation of raw water decreased DBP formation potentials (DBPFPs) by about 30% for trihalomethanes (THMs), 40% for trihaloacetic acids (THAAs), 10% for dihaloacetic acids (DHAAs), 30% for dihaloacetonitriles (DHANs), and 5% for haloketones (HKs). The formation potential of chloropicrin (CP) consistently increased after direct ferrate oxidation. Pre-ferrate followed by conventional treatment was similar to conventional treatment alone for NOM and DBP precursor removal. Ferrate pre-oxidation had positive effects on subsequent coagulation/particle removal for THM and THAA precursor removal and may allow the use of lower coagulant doses due to the Fe(III) introduced by ferrate decomposition. On the other hand, intermediate-ferrate resulted in substantially improved removal of NOM and DBP precursors, which can be attributed to initial removal by coagulation and particle removal, leaving precursors that are particularly susceptible to oxidation by ferrate. The Fe(III) resulting from ferrate decay during intermediate-ferrate process was primarily present as particulate iron and could be effectively removed by filtration.

An Improved Method for Determination of Fumigant Degradation Half‐Life in Soil

Core Ideas Degradation of fumigants is an important component of their fate and transport. Traditional measurement of half‐life is limited by the large headspace in an incubation vial. A novel approach is presented that eliminates the incubation vial headspace. This novel approach yields shorter fumigant half‐lives due to greater contact with soil. Using the current approach, measurement of fumigant degradation half‐lives under realistic soil conditions is problematic due to the large headspace that is necessary above the soil during incubation. This results in a poor degree of contact between the fumigant and the soil's degrading surfaces, which differs markedly from field conditions. We report a simple, novel approach for determining fumigant degradation half‐lives in which the fumigant is in complete contact with the soil during incubation (no headspace) and which uses gastight, nonsorbing equipment commonly found in pesticide research laboratories. The approach was tested on a sandy loam soil. At both 23 and 50°C, the novel approach yielded much lower degradation half‐lives for cis‐ and trans‐1,3‐dichloropropene (1,3‐D) isomers and chloropicrin (CP) than the traditional approach. Percentage reductions ranged from 22 to 64% and were greater at the higher temperature. The results suggest that literature‐reported half‐lives of soil fumigants, and consequently their modeled soil–air emission rates, may be overestimated. The novel approach could potentially be applied to determining the degradation kinetics of other classes of volatile chemicals in soil.

Dissipation kinetics of pre-plant pesticides in greenhouse-devoted soils

This work was conducted to study the distribution of methyl isothiocyanate (MITC) in greenhouse soils treated with the fumigant dazomet (DZ) from the formulated product “Basamid Granular®”, but also of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) from the fumigant “Agrocelhone NE®”. In order to achieve this aim, several methods for the determination of fumigants residues in soils, but also pepper fruits were optimized and characterized. With independence of the soil depth, no residues of MITC, 1,3-D and CP above the detection limits were observed in soils covered with a polyethylene (PE) film (0.04mm thick) after 27, 13 and 8days of treatment, respectively. Liberation and dissipation curves of MITC in soil in presence of a PE film (0.04mm) used to limit volatilization losses were also obtained. According to the results, the rate of decomposition of DZ into MITC have a half-life of 3.7days in the surface horizon (5–10cm) of the soil while in the subsurface horizon (15–20cm), MITC formation rate is slightly slow (half-life of 3.2days). With respect to the dissipation process, half-lives lower than 1day were obtained for both depths (0.8 and 0.9 for the surface and the subsurface horizon, respectively). In the case of 1,3-D and CP in soil, the dissipation half-life of 1,3-D on soils was a bit higher than for CP (2days vs. 1). In addition, the presence of residues of the fumigants on green pepper fruits grown on the treated soils was not detected as expected.

Effect of application rate on fumigant degradation in five agricultural soils

Soil fumigation is an important pest management tool for many high value crops. To address the knowledge gap of how fumigant concentration in soil impacts dissipation, and thereby efficacy, this research determined the degradation characteristics of four fumigants as affected by application rate. Laboratory incubation experiments were conducted to determine degradation rates of 1,3-dichloropropene (both cis- and trans isomers), chloropicrin (CP), dimethyl disulfide (DMDS), and methyl iodide (MeI) in five agricultural soils. Fitted to pseudo first-order kinetics, the degradation rate constant (k) of CP, DMDS, and MeI decreased significantly as application rate increased while the 1,3-D isomers were the least affected by rate. Half-lives increased 12, 17, and 6-fold for CP, DMDS, and MeI, respectively, from the lowest to the highest application rate. At low application rates, the degradation rate of all fumigants in the Hueneme sandy loam soil was reduced by 50–95% in sterilized soil compared to the biologically active controls. However, this difference became much smaller or disappeared at high application rates indicating that biodegradation dominates at low concentrations but chemical degradation is more important at high concentrations. When co-applied, CP degradation was enhanced with biodegradation remained above 50%, while 1,3-D degradation was either reduced or not changed. Among the fumigants tested, the relative importance of biodegradation was DMDS>CP>MeI>1,3-D. These results are useful for determining effective fumigation rates and for informing regulatory decisions on emission controls under different fumigation scenarios.

Chloropicrin Emission Reduction by Soil Amendment with Biochar.

Biochar has sorption capacity, and can be used to enhance the sequestration of volatile organic contaminants such as pesticides in soil. Chloropicrin (CP) is an important soil fumigant for the production of many fruit and vegetable crops, but its emissions must be minimized to reduce exposure risks and air pollution. The objective of this study was to determine the capacity of biochar to adsorb CP and the effect of biochar amendments to soil on CP emission, concentration in the soil gas phase, degradation in soil and CP bioactivity for controlling soil borne pests. CP emission and concentration in the soil air phase were measured from packed soil columns after fumigant injection at 20-cm depth and application of selected doses of biocharto the surface 5 cm soil. Laboratory incubation and fumigation experiments were conducted to determine the capacity of biochar to adsorb CP, the effects on CP degradation and, separately, CP’s bioactivity on soil borne pests in soil amended with biochar. Biochar amendment at 2% to 5% (w/w) greatly reduced total CP emission losses by 85.7% - 97.7% compared to fumigation without biochar. CP concentrations in the soil gas-phase, especially in the top 5 cm of soil, were reduced within 48 h following application. The half-life of CP decreased from 13.6 h to 6.4 h as the biochar rate increased from 0% to 5%. CP and its metabolite (dichloronitromethane) both degraded more rapidly in pure biochar than in soil. The biochar used in the present study had a maximum adsorption capacity for CP of less than 5 mg g-1. There were no negative effects on pathogen and nematode control when the biochar used in this study was less than 1% (on a weight basis) in soil. Biochar amendment to soil reduced the emissions of CP. CP concentrations in the top 5 cm of soil gas-phase were reduced. CP degradation was accelerated with the addition of biochar. The biochar used in the present study had a low adsorption capacity for CP. There were no negative effects on pathogen and nematode control when the biochar amendment rate was less than 1% (by weight). The findings would be useful for establishing guidelines for biochar use in soil fumigation.

Effect of Co-formulation of 1,3-Dichloropropene and Chloropicrin on Evaporative Emissions from Soil

Co-formulations of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) are commonly used for preplant fumigation in the production of high-value crops. Various ratios of 1,3-D to CP are available in these co-formulations. Collation of previous field data suggested that when the two fumigants were co-applied, the emissions of CP were significantly lower than when CP was applied singly. However, none of these previous studies had a control treatment with CP applied alone, alongside a treatment where CP was co-applied with 1,3-D under the same climatic and edaphic conditions. This work aimed to address this issue by measuring emission fluxes from soil columns maintained under controlled conditions in which 1,3-D and CP were applied alone and as four commercial co-formulations with various 1,3-D:CP ratios. A strong positive relationship between CP emissions and CP percentage in the formulation was observed. Furthermore, strong positive relationships between CP degradation half-life and CP percentage in the formulation and between CP degradation half-life and total column emissions suggested that the lower emissions were due to faster CP degradation when the CP percentage (and hence initial application mass) in the formulation was low. The presence of 1,3-D did not significantly affect the degradation rate of CP, and, therefore, it is hypothesized that co-application was, in itself, not a significant factor in emission losses from the columns. The findings have implications for the accurate modeling of CP because the effect of initial mass applied on CP degradation rate is not usually considered.

Effects of household handling on disinfection by- products

Chlorinated water samples were used to determine the effect of handling modes on disinfection byproducts (DBPs). The DBPs studied were trihalomethanes (THMs), haloacetonitriles (HANs), chloral hydrate (CH), chloropicrin (CP) and 1,1,1-trichloropropanone (TCP). Tap water samples were collected from the distribution system in Damanhour City (Egypt). The investigated strategies included storing water in covered and uncovered bottles in a refrigerator up to 9 hours, with and without previous short boiling. Water quality parameters were not affected by storage or boiling except for electrical conductivity (EC), which decreased after boiling. 90% of THMs were removed by boiling and storage for 9hrs.HANs, including dichloroacetonitrile (DCAN), dibromoacetonitrile (DBAN) and trichloroacetonitrile (TCAN), were not affected by storage, but they were not detected after boiling for 30 seconds. CH and TCP, like the HANs, were affected by boiling rather than storage.

Disparity in disinfection byproducts concentration between hot and cold tap water

The quality of water entering a distribution system may differ substantially from the quality at the point of exposure to the consumer. This study investigated temporal variations in the levels of regulated and non-regulated disinfection byproducts (DBPs) in cold and hot tap water in a home on a medium-sized municipal water system. In addition, samples were collected directly from the water plant with some being held in accordance with a simulated distribution system (SDS) test protocol. The location for this work was a system in western Massachusetts, USA that uses free chlorine as a final disinfectant. Very little short term variability of DBPs at the point of entry (POE) was observed. The concentration of DBPs in the time-variable SDS test was similar to concentrations in the cold water tap. For most DBPs, the concentrations continued to increase as the cold water tap sample was held for the time-variable SDS incubation period. However, the impact of heating on DBP levels was compound specific. For example, the concentrations of trihalomethanes (THMs), dichloroacetic acid (DCAA) and chloropicrin (CP) were substantially higher in the hot water tap than in the cold water time-variable SDS samples. In contrast, the concentration of trichloroacetic acid (TCAA) was lower in the heated hot tap water, but about equal to that observed in the cold tap water. The situation was more pronounced for dichloroacetonitrile (DCAN), bromodichloroacetic acid (BDCAA), bromochloroacetic acid (BCAA) and 1,1,1-trichloropropanone (TCP), which all showed lower concentrations in the hot water then in either of the cold water samples (instantaneous or time-variable SDS). The latter was viewed as a clear indication of thermally-induced decomposition. The ratio of unknown total organic halide (UTOX) to TOX was substantially lower in the hot tap water as the THM to TOX ratio became correspondingly larger. The results of this study show that DBP exposure in the home is not well represented by concentrations measured in cold water taps where most compliance monitoring is done.

Evaluation of chemical alternatives to methyl bromide in tomato crops in China

Tomato is a high-value cash crop in China that requires vigorous transplants free of pathogens. However, local tomato growers commonly face heavy root-knot nematode and weed infestations, especially while phasing out methyl bromide (MB). The soil fumigants chloropicrin (CP), 1,3-dichloropropene (1,3-D) and dazomet (DZ) were evaluated at several rates alone and in combination as alternatives to MB soil fumigation in tomato production. Field trials revealed that used alone, CP, 1,3-D and DZ were not comparable to MB in the reduction of Meloidogyne incognita, weeds or increase of tomato marketable yield. Only the combination of reduced rates of 1,3-D and CP which had excellent nematicide efficacy and good to moderate weed control, matched the efficacy of MB. The present data indicate that the combination of 1,3-D plus CP is an efficient MB alternative for managing nematodes and weeds in tomato crops and can be used in integrated pest management programs. To get a better weeds control efficacy, it is recommended to add herbicides to the two fumigants combination.

Quantification of Fusarium oxysporum in fumigated soils by a newly developed real-time PCR assay to assess the efficacy of fumigants for Fusarium wilt disease in strawberry plants

Two soil fumigants, chloropicrin (CP) and dimethyl disulfide (DMDS), were used to control Fusarium wilt disease (FWD) which caused large economic losses in strawberries. The fumigants were evaluated alone and in combination in a laboratory study and in strawberry greenhouses. Laboratory tests found that combinations of CP and DMDS indicated a positive synergistic activity on Fusarium oxysporum. A newly developed quantitative assay for F. oxysporum involving real-time PCR was used successfully to evaluate F. oxysporum control by the fumigants; it provided similar results to the selective medium but was less time-consuming and less labor intensive. Greenhouse trials revealed that the combination of CP and DMDS successfully suppressed the incidence of FWD and sharply reduced the population density of F. oxysporum, which significantly increased fruit branch number and maintained a good strawberry yield, higher than methyl bromide (MB) treatment. All of the treatments provided significantly better results than the non-treated control. This study confirms that the newly developed real-time PCR quantitative assay for F. oxysporum was suitable for the control efficacy evaluation of soil fumigants and that the novel fumigant combination of CP and DMDS offers a promising effective alternative to MB for the control of F. oxysporum in strawberry greenhouses.

Examination of disinfection by-product (DBP) formation in source waters: A study using log-transformed differential spectra

Formation of disinfection by-products (DBPs) in ten drinking source waters located in the United States was examined in this study. DBP generation was interpreted in the context of halogenation-induced changes of log-transformed absorbance spectra of dissolved organic matter (DOM) present in the waters. This approach allows probing the behavior of relatively minor structures that can be highly sensitive towards any process of interest, notably DOM halogenation. This concept was applied to examine effects of chlorination time on the kinetics of chlorine consumption and release of several DBP groups such as total trihalomethanes (THM4, including CHCl3, CHCl2Br, CHClBr2 and CHBr3), haloacetic acids (HAA9, including MCAA, MBAA, DCAA, TCAA, BCAA, DBAA, BDCAA, DBCAA and TBAA), haloacetonitriles (THAN4, including TCAN, DCAN, BCAN and DBAN), haloketones (HK2, including DCP and TCP), chloral hydrate (CH) and chloropicrin (CPN). Two alternative parameters, namely the differential logarithm of DOM absorbance at 350 nm (DLnA350) and change of the spectral slope in the range of wavelengths 325–375 nm (DSlope325-375) were introduced to quantify individual DBP species formed and Cl2 consumption. DLnA350 and DSlope325-375, especially DLnA350 were determined to be more reliable than differential absorbance at 272 nm that was utilized in prior applications of differential spectroscopy to characterize DBP formation. Strong linear relationships between DLnA350 values and concentrations of major groups of and individual DBP species (e.g. THM4, HAA9, HAN4 and CPN were found to exist (mostly, R2 > 0.95) and the intercept of these correlations with the y-axis was near zero for the examined water sources. Correlations between DLnA350 values and concentrations of CH and HK2 were also strong but they were nonlinear. The slope of the correlations between the concentrations of major groups of DBP species vs -DLnA350 were also well correlated with SUVA254 and LnA350 for all the examined source waters. It indicates that log-transformations of the absorbance spectra of surface water and parameters based on such transformations (e.g., DLnA350 and DSlope325-375) have a potential to provide an alternative reliable approach to monitor the halogenation of DOM and attendant formation of individual DBP species.

Elemental and Molecular Composition of Terminalia Brownii's Bark

Tarminalia Brownii is a plant used for many purposes. It is used as a source of fire wood, for animal fodder or as a traditional medication for a number of diseases. The chemical elements and compounds present in the plant's bark were investigated using a number of analytical techniques, in order to collect more information pertaining to the chemistry of the plant's bark. Powdered air dried bark chips were analyzed for their contents of: dry matter (DM), moisture, crude protein, total Kjeldahl Nitrogen (TKN) and acid detergent fiber (ADF). In addition elemental and molecular compositions were investigated using ICP and FT-IR, while XRF was utilized to determine the crystalline state. The bark samples are found to contain high calcium concentrations (68%) present in the form of calcium and potassium oxalates, Chloropicrin and Diphosphoryl chloride. Only calcium oxalate monohydrate (Whewellite) is present in crystalline form

Fumigants and VOCs in ocean freight containers – Identification, exposure and prevention

Carbonated fumigants have been shown to distribute quickly and uniformly in sandy soils and improve pest control efficacy for annual crops. Low permeability films, such as VaporSafe® (TIF), could further improve fumigant dispersion by effectively retaining the fumigant in soil; however, there is a concern that the TIF can lead to higher off-tarp edge emissions. An orchard field trial was conducted to determine the off-tarp emissions, distribution, efficacy, and fate of carbonated Telone® C35 [63.4% 1,3-dichloropropene (1,3-D), 34.7% chloropicrin (CP)] that was shank-injected at 46 cm soil depth. Treatments included carbonated fumigants at full- or 2/3 rates and a full rate of regular (nitrogen-pressurized) fumigants covered with standard polyethylene (PE) film, TIF, or no surface seal. Fumigant emissions at the regular tarp edge (25 cm from the shank line) peaked at 3.98 μg m− 2 s− 1 for 1,3-D and 0.05 μg m− 2 s− 1 for CP. The addition of a TIF tarp extension (to 85 cm from the shank line) reduce peak off-tarp emissions to < 1 and < 0.03 μg m− 2 s− 1 for 1,3-D and CP, respectively. Fumigant concentration under TIF was usually at least twice that under PE regardless of carbonation. Carbonation at 345 KPa with 1.5% of dissolved CO2 did not significantly improve fumigant dispersion in soil profile compared to the conventional nitrogen pressurization. In a citrus nematode bioassay, only the 2/3 rate of carbonated fumigation treatment sealed with PE failed to control nematodes at 25 cm away from shank line. This research indicates that a 60-cm TIF extension can effectively reduce off-tarp edge emissions in strip fumigation treatments. While the adaptability of carbonation of fumigants is still questionable, further research efforts are needed in finding effective solutions to control plant parasitic nematodes, which remain a challenge in orchard fumigation.