Comparative assessment of pesticide residues in grain, soil, and water from IPM and non-IPM trials of basmati rice

The integrated pest management (IPM) modules of pesticide schedule on Basmati rice were validated at field experiments conducted in Northern India for consecutive 3 years (2005–2008). The pesticide residues were found below the detectable limit (<0.01–0.001 mg/kg) in soil and irrigation water samples of Kaithal region. In Dehra Dun region of Uttrakhand, the residues of carbendazim in rice grains and soil were detected below <0.01 mg/kg level. In second year experiments (2006–2007), only four non-IPM soil samples indicated the presence of chlorpyrifos and endosulfan in the range of ND <0.001 to 0.07 mg/kg, out of 45 samples analyzed. Carbendazim applied as seed treatment at Dehradun and Kaithal field trials was found below detectable limit in both IPM and non-IPM rice grains (<0.01 mg/kg) and irrigation water (0.01 μl/ml). Chlorpyrifos was detected in five water samples from Kaithal and one from Pant Nagar in the range of 0.003–0.006 μl/L, α- and β-isomer of endosulfan in the range of 0.005–0.03, and 0.005–0.02 μl/ml, respectively, in one sample from Pant Nagar and two from Kaithal, out of a total of 22 samples. In the region of Uttrakhand and Uttar Pradesh during 2007–2008, four non-IPM samples of soil indicated trace levels of endosulfan, out of 16 samples analyzed. The residues were detected below detection limit for carbendazim (<0.01 mg/kg) in soil samples of Dehradun IPM fields and for endosulfan and carbendazim (0.001–0.01 μl/L) in water samples each from IPM and non-IPM fields of Uttar Pradesh. The results of 3-year trials of IPM module indicated basmati rice as safe and economical with pesticide residue-free rice grains.     

Analysis of insecticides in okra and brinjal from IPM and non-IPM fields

Samples of okra and brinjal fruits, collected from non-integrated pest management (Non-IPM) and IPM fields in village Raispur, Ghaziabad District (U.P.), were analyzed for pesticide residues. The residues of chlorpyrifos in soil were 4.219 and 1.135 microg/g at harvest time in non-IPM and IPM fields of summer okra crop from initial value of 0.407 microg/g before sowing, while in brinjal crop, it was not detected in soils of any trials. During first year of study, the residues of chlorpyrifos and cypermethrin in okra fruit were observed to be 5.75 and 0.625 microg/g, respectively, for non-IPM fields; and 0.104 microg/g of chlorpyrifos for IPM trials. The pesticide residues were found to be 0.77, 1.39, 0.4 and 0.32 microg/g for cypermethrin, chlorpyrifos, monocrotophos and dimethoate, respectively, for non-IPM okra fruits in second year. For brinjal fruit, residues of cypermethrin and imidacloprid were not detected in IPM trials while it was found to be 0.28 and 0.78 microg/g for cypermethrin and chlorpyrifos respectively, for non-IPM trials.     

Dissipation and residues of bispyribac-sodium in rice and environment

The dissipation and residues of bispyribac-sodium in rice cropping system were studied. Bispyribac-sodium residues were extracted by a simple analytical method based on QuEChERs and detected by LC-MS/MS. The limit of detection for bispyribac-sodium of this method was 0.375?×?10^?3 ng. The limit of quantification (LOQ) was 5.0 μg/kg for rice plant samples, 2.0 μg/kg for rice hull, 0.2 μg/kg for water, and 0.1 μg/kg for soil and husked rice samples. The average recoveries of bispyribac-sodium ranged from 74.7 to 108 %, with relative standard deviations less than 13 %. The half-lives of bispyribac-sodium in rice plant, water, and soil were in the range of 1.4–5.6 days. More than 90 % of bispyribac-sodium residue dissipated within 5 days. The final residues of bispyribac-sodium in rice were all below LOQ at harvest time.     

Determination of imazosulfuron persistence in rice crop and soil

Imazosulfuron is a new post-emergence sulfonylurea herbicide. It is highly active at low application rates to control annual and perennial broad-leaf weeds and sedges in rice. There is increasing concerned about the persistence of pesticide residues in soils, crop produce and subsequent contamination of groundwater. Thus persistence of imazosulfuron residues under field condition was evaluated. Imazosulfuron was applied at 30, 40, 50 and 60 a. i. g ha ⁻¹ rates, 4 days after transplanting of rice as post-emergence herbicide. Soil and plant samples treated with imazosulfuron were collected at 60, 90 and 120 days after herbicide application and analyzed for residues. Rice grains and straw samples were sampled at harvest (120 days). Residues of imazosulfuron in soil were not found after 90 and 120 DAS (days after spraying). Rice grains contained 0.006, 0.009 μg g⁻¹ residues at 50 and 60 g ha ⁻¹ application rates. 0.009 and 0.039 μg g⁻¹ residues of imazosulfuron were detected at 50 and 60 g/ha rates respectively in rice straw. Residues of imazosulfuron were not detected applied at 30 and 40 g ha⁻¹ in rice grains and straw, respectively and can be safely applied to the transplanted rice.     

Dissipation of flubendiamide residues in/on cabbage (Brassica oleracea L.)

Residues of fubendiamide and its metabolite desiodo flubendiamide were estimated in cabbage and soil using high-performance liquid chromatography with UV–vis detector. The initial deposits of flubendiamide residues on cabbage were found to be 0.16 and 0.31 μg g^?1 following two applications of flubendiamide 20 WG at 12.5 (standard dose) and 25 (double dose) g a.i. ha^?1 respectively at 10-days interval. The half-life values (t _1/2) of flubendiamide on cabbage ranged from 3.4 to 3.6 days. When flubendiamide applied at both the standard and double dose, no detectable residues were found in cabbage and soil at harvest. Thus, a waiting period of 1.63 days was suggested for the safe consumption of flubendiamide-treated cabbage. These data could provide guidance for the proper and safe use of this pesticide on cabbage crops in India.     

Assessment of pesticide residues in vegetables from the Western Usambara and Uruguru Mountains in Tanzania

Assessment of levels of pesticide residues in vegetables was carried out in some villages in the Western Usambara and Uluguru Mountains of Tanzania where varieties of vegetables are grown. Tomatoes and cabbages were the most popular enterprise grown all year round and therefore were selected as the model crops for this study. Analysis of the cleaned sample extracts on a gas chromatography with electron capture detector (GC-ECD) and confirmation on the Gas chromatography–mass spectrometry (GC-MS) revealed dominance of organochlorine pesticides. Organophosphorous pesticides (parathion and marathion) were only detected in some samples, however, in most cases with higher concentrations compared to organochlorine pesticides. Levels of pesticide residues detected in vegetables were up to: parathion 5.07 μg/Kg, marathion 3.73 μg/Kg, α-endosulfan 0.32 μg/Kg, β-endosulfan 0.53 μg/Kg, dieldrin 1.36 μg/Kg, γ-HCH 0.25 μg/Kg, α-HCH 0.09 μg/Kg, and p, p′-DDT 0.64 μg/Kg. These results clearly show that vegetables are contaminated with different pesticide residues. However, the total levels of pesticide residues in both tomatoes and cabbages are lower than their respective codex alimentarius maximum residue levels (MRLs). This means that the vegetables produced in the area are suitable for human consumption.     

Status and effect of pesticide residues in soils under different land uses of Andaman Islands, India

Pesticides are shown to have a great effect on soil organisms, but the effect varies with pesticide group and concentration, and is modified by soil organic carbon content and soil texture. In the humid tropical islands of Andaman, India, no systematic study was carried out on pesticide residues in soils of different land uses. The present study used the modified QuEChERS method for multiresidue extraction from soils and detection with a gas chromatograph. DDT and its various metabolites, α-endosulfan, β-endosulfan, endosulfan sulfate, aldrin, and fenvalerate, were detected from the study area. Among the different pesticide groups detected, endosulfan and DDT accounted for 41.7 % each followed by aldrin (16.7 %) and synthetic pyrethroid (8.3 %). A significantly higher concentration of pesticide residues was detected in rice–vegetable grown in the valley followed by rice–fallow and vegetable–fallow in the coastal plains. Soil microbial biomass carbon is negatively correlated with the total pesticide residues in soils, and it varied from 181.2 to 350.6 mg?kg^?1. Pesticide residues have adversely affected the soil microbial populations, more significantly the bacterial population. The Azotobacter population has decreased to the extent of 51.8 % while actinomycetes were the least affected though accounted for 32 % when compared to the soils with no residue.     

Assessment of the labile fractions of copper and zinc in marinas and port areas in Southern Brazil

The dissolved labile and labile particulate fractions (LPF) of Cu and Zn were analyzed during different seasons and salinity conditions in estuarine waters of marina, port, and shipyard areas in the southern region of the Patos Lagoon (RS, Brazil). The dissolved labile concentration was determined using the diffusive gradients in thin films technique (DGT). DGT devices were deployed in seven locations of the estuary for 72 h and the physicochemical parameters were also measured. The LPF of Cu and Zn was determined by daily filtering of water samples. Seasonal variation of DGT–Cu concentrations was only significant (p?<?0.05) at one shipyard area, while DGT–Zn was significant (p?<?0.05) in every locations. The LPF of Cu and Zn concentrations demonstrated seasonal and spatial variability in all locations, mainly at shipyard areas during high salinity conditions. In general, except the control location, the sampling locations showed mean variations of 0.11–0.45 μg?L^?1 for DGT–Cu, 0.89–9.96 μg?L^?1 for DGT–Zn, 0.65–3.69 μg?g^?1 for LPF–Cu, and 1.35–10.87 μg?g^?1 for LPF–Zn. Shipyard areas demonstrated the most expressive values of labile Cu and Zn in both fractions. Strong relationship between DGT–Zn and LPF–Zn was found suggesting that the DGT–Zn fraction originates from the suspended particulate matter. Water salinity and suspended particulate matter content indicated their importance for the control of the labile concentrations of Cu and Zn in the water column. These parameters must be taken into consideration for comparison among labile metals in estuaries.     

Investigating Jacaranda mimosifolia tree as biomonitor of atmospheric trace metals

Studies on the use of tree bark as biomonitors for environmental pollutants are still very scarce. We evaluated the reliability of using Jacaranda mimosifolia, a common tree in Tshwane City of South Africa, as a suitable biomonitor of atmospheric trace metals. Bark samples were collected from ten different locations during two sampling periods. The concentrations of the metals were determined by inductively coupled plasma mass spectrometry. The concentrations of the metals were 33.2–1,795 μg/g (Pb), 21.4–210 μg/g (Cu), 68.4–490 μg/g (Zn), 30.6–2,916 μg/g (Cr), 0.12–1.34 μg/g (Cd), and 6.04–68.0 μg/g (V), respectively. The differences obtained for the results from different sites were significant (p?< 0.05). A significant difference was also observed between the two sampling periods. The trace metals concentrations suggested that automobile emissions are a major source of these metals. The study also confirms the suitability of J. mimosifolia as a biomonitor of atmospheric deposition of these metals.     

Presence of pesticide residues on produce cultivated in Suriname

Agricultural pesticides are widely used in Suriname, an upper middle-income Caribbean country located in South America. Suriname imported 1.8 million kg of agricultural pesticides in 2015. So far, however, national monitoring of pesticides in crops is absent. Reports from the Netherlands on imported Surinamese produce from 2010 to 2015 consistently showed that samples exceeded plant-specific pesticide maximum residue limits (MRLs) of the European Union (EU). Consumption of produce containing unsafe levels of pesticide residues can cause neurological disorders, and particularly, pregnant women and children may be vulnerable. This pilot study assessed the presence of pesticide residues in commonly consumed produce items cultivated in Suriname. Thirty-two insecticides (organophosphates, organochlorines, carbamates, and pyrethroids) and 12 fungicides were evaluated for their levels in nine types of produce. Pesticide residue levels exceeding MRLs in this study regarded cypermethrin (0.32 μg/g) in tomatoes (USA MRL 0.20 μg/g), lambda-cyhalothrin (1.08 μg/g) in Chinese cabbage (USA MRL 0.40 μg/g), endosulfan (0.07 μg/g) in tannia (EU MRL 0.05 μg/g), and lindane (0.02 and 0.03 μg/g, respectively) in tannia (EU MRL 0.01 μg/g). While only a few pesticide residues were detected in this small pilot study, these residues included two widely banned pesticides (endosulfan and lindane). There is a need to address environmental policy gaps. A more comprehensive sampling and analysis of produce from Suriname is warranted to better understand the scope of the problem. Preliminary assessments, using intake rate, hazard quotient, and level of concern showed that it is unlikely that daily consumption of tannia leads to adverse health effects.     

Safety evaluation of flubendiamide and its metabolites on cabbage and persistence in soil in different agroclimatic zones of India

Supervised field trials following good agricultural practices were conducted at the research farms of four agricultural universities located at four different agroclimatic zones of India to evaluate the persistence and dissipation of flubendiamide and its metabolite, des-iodo flubendiamide, on cabbage. Two spray applications of flubendiamide 480 SC of standard and double dose at the rate of 24 and 48 g a.i. ha^?1 were given to the crop at a 15-day interval, and the residues of flubendiamide 2 h after spray were found in the range of 0.107–0.33 and 0.20–0.49 mg kg^?1 at respective doses. Residue of des-iodo flubendiamide was not detected in any cabbage sample during study period. No residues were found in the soil samples collected from all treated fields after 15 days of application. On the basis of data generated under All India Network Project on Pesticide Residues, a preharvest interval (PHI) of 10 days has been recommended, and the flubendiamide 480 SC has been registered for its use on cabbage by Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India. The maximum residue limit (MRL) of flubendiamide on cabbage has been fixed by the Ministry of Health and Family Welfare, Government of India, under Food Safety Standard Authority of India as 0.05 μg/g after its risk assessment.     

Total petroleum hydrocarbons and trace heavy metals in roadside soils along the Lagos–Badagry expressway, Nigeria

This study reports the level of total petroleum hydrocarbons (TPH) and trace heavy metals (lead, copper, and cadmium) in soil samples collected randomly from Iyana–Iba garage, Lagos State University bus stop, Adeniran Ogunsanya College of Education bus stop, and a control site off Lusada–Atan road, near Crawford University, Igbesa, Ogun state. TPH was estimated gravimetrically after Soxhlet extraction and column clean up, while soil metals were determined by atomic absorption spectrometry using mineral acid digestion. For TPH, the sites have mean values of 19.43 ± 1.27, 16.11 ± 1.85, and 11.43 ± 4.33 mg/g with a control mean value of 0.33 ± 0.16 mg/g. For trace heavy metals, cadmium was not detected. However, the mean levels of lead are 4.24 ± 3.10, 3.72 ± 0.60, and 3.70 ± 1.32 μg/g, respectively, whereas mean copper concentrations are 20.63 ± 9.02, 19.35 ± 3.61, and 16.76 ± 3.02 μg/g in all sites, respectively, compared to the control mean of 0.25 ± 0.13 and 5.99 ± 1.23 μg/g for lead and copper, respectively. Sites studied have higher levels of TPH and metals compared to the control soil samples. This is indicated by a statistically significant difference found between the concentration of analyzed elements in soils collected along Lagos–Badagry expressway and the control site.     

Metal pollution and ecological risk assessment in marine sediments of Karachi Coast, Pakistan

Concentrations of 12 metals (Fe, Mn, Cr, Mo, Ni, Pb, Se, Sr, U, V, Zn, and Zr) in surface sediments of Karachi Coast, Pakistan were determined to evaluate their distribution and pollution assessment. The measured metals in the sediments were found to be in the range of Fe, 0.84–6.96 %; Mn, 300–1,300 μg/g; Cr, 12.0–319.84 μg/g; Mo, 0.49–2.03 μg/g; Ni, 1.53–58.86 μg/g; Pb, 9.0–49.46 μg/g; Se, 0.25–.86 μg/g; Sr, 192–1185 μg/g; U, 0.19–1.66 μg/g; V, 15.80–118.20 μg/g; Zn, 15.60–666.28 μg/g; and Zr, 44.02–175.26 μg/g. The mean contents of the metal studied were: Fe, 3.07 %, Mn, 0.05 %; Cr, 96.75 μg/g; Mo, 1.34 μg/g; Ni, 31.39 μg/g; Pb, 23.24 μg/g; Se, 0.61 μg/g; Sr, 374.83 μg/g; U, 0.64 μg/g; V, 61.75 μg/g; Zn, 204.75 μg/g; and Zr:76.27 μg/g, and arrangement of the metals from higher to lower mean content in this area is: Fe?>?Zn?>?Mn?>?Sr?>?Zn?>?Cr?>?Zr?>?V?>?Ni?>?Pb?>?Mo?>?U?>?Se. There is no significant correlation among most of these metals, indicating different anthropogenic and natural sources. To assess ecotoxic potential of marine sediments, Numerical Sediment Quality Guidelines were also applied. The concentration of Pb in all the sediments except one was lower than the threshold effect concentration (TECs) showing that there are no harmful effects to marine life from Pb. On the other hand, the concentrations of Cr, Ni, and Zn exceeded TEC in three stations, indicating their potential risk. The degree of pollution in sediments for metals was assessed by calculating enrichment factor (EF) and pollution load index (PLI). The results indicated that sediments of Layari River Mouth Area, Fish Harbour, and KPT Boat Building Area are highly enriched with Cr and Zn (EF?>?5). Sediments of Layari River Outfall Zone were moderately enriched with Ni and Pb (EF?>?2). The pollution load index was found in the range of 0.98 to 1.34. Lower values of PLI (≤1) at most of sampling locations imply no appreciable input from anthropogenic sources. However, relatively higher PLI values (>1) at Layari River Mouth Area, Fish Harbour, and KPT Boat Building Area are attributed to increased human activity in the area.     

Leaching behaviour of chlorpyriphos and cypermethrin in sandy loam soil

The mobility of chlorpyriphos and cypermethrin in sandy loam soil was studied in soil columns under laboratory conditions at two application rates, 25 and 50 μg, with simulated rainfall of 300 mm. Residues of chlorpyriphos and cypermethrin in soil and leachate were estimated by gas–liquid chromatography and confirmed by gas chromatography–mass spectrometry. Though maximum concentration of both the insecticides was found in the top 10-cm layer, chlorpyriphos was found distributed in the soil up to a depth of 35 cm and cypermethrin remained up to 15 cm. Results indicated the low mobility of both the insecticides under saturated moisture condition and hence may not contaminate ground water. No residues of any insecticide were detected in the leachate fractions.     

Persistence of dicofol residues in cotton lint seed, and soil

A supervised field trial was conducted at the CCS Haryana Agricultural University, Hisar to assess the residues of dicofol on cotton, during Kharif season, 2008. Dicofol (Kelthane 18.5EC) was applied at 500 g a.i./ha (T(1)) and 1,000 g a.i./ha T(2)) after 105 days of sowing of cotton crop (Varity Cotton/H-1226). Soil samples were collected on 0 (1 h after treatment), 3, 7, 10, 15, 30, and 60 days after spray and cotton samples were collected at harvest. Samples were processed and residues were quantified by GC-ECD system equipped with capillary column. Limit of detection and limit of quantification (LOQ) were 0.001 and 0.010 mg kg(?-1), respectively, for soil and LOQ for cotton lint and seed was 0.020 mg kg(?-1). Initial residues of 0.588 and 1.182 mg kg(?-1) in soil reached below detectable level (BDL) of 0.010 mg kg(?-1) in T(1) and to the level of BDL (0.010 mg kg(?-1)) in T(2) at harvest (60 days after treatment). In 60 days, residues dissipated almost completely (100 and >99%) in both the treatments. Half-life period was calculated as 8.57 days at single dose and 8.69 days at double dose in soil. Residues of dicofol were detected in cotton lint to the levels of 0.292 and 0.653 mg kg(?-1) and in seed 0.051 and 0.090 mg kg(?-1) in T(1) and T(2) doses, respectively at harvest. Residues in cotton seed were below MRL value of 0.01 mg kg(?-1) in both the doses.     

Effects of northeast monsoon on trace metal distribution in the South China Sea off Peninsular Malaysia

Concentrations of trace metals in the South China Sea (SCS) were determined off the coast of Terengganu during the months of May and November 2007. The concentrations of dissolved and particulate metals were in the range of 0.019–0.194 μg/L and 50–365 μg/g, respectively, for cadmium (Cd), 0.05–0.45 μg/L and 38–3,570 μg/g for chromium (Cr), 0.05–3.54 μg/L and 21–1,947 μg/g for manganese (Mn), and 0.03–0.49 μg/L and 2–56,982 μg/g for lead (Pb). The order of mean log K _D found was Cd?>?Cr?>?Pb?>?Mn. The study suggests that the primary sources of these metals are discharges from the rivers which drain into the SCS, in particular the Dungun River, which flows in close proximity to agricultural areas and petrochemical industries. During the northeast monsoon, levels of particulate metals in the bottom water samples near the shore were found to be much higher than during the dry season, the probable result of re-suspension of the metals from the bottom sediments.     

Distribution of phthalate esters in topsoil: a case study in the Yellow River Delta, China

The Yellow River Delta (YRD) is a typical agricultural and petrochemical industrial area of China. To assess the current status of phthalate esters (PAEs) of soil residues, soil samples (0～20 cm) (n?=?82) were collected in Bincheng District, at the geographic center of the YRD. PAEs were detected in all topsoil samples analyzed, which indicated that PAEs are ubiquitous environmental contaminants. Concentrations of 11 PAEs are in the range of 0.794～19.504 μg g^?1, with an average value of 2.975 μg g^?1. It was presented that PAEs pollution in this area was weak and monotonously increasing along the rural–urban gradient. Higher concentrations were observed from roadsides (and/or gutters), densely anthropogenic activities areas (such as the urbanization and industrialization), and agriculture influence district, which mainly originated from construction waste, municipal sewage, agricultural waste and pesticide, discarded plastic effusion and atmospheric depositions. Concentrations of PAEs were weakly positivity correlated with soil organic carbon content and pH, which suggested both of them can affect the distribution of PAEs. The concentration of di (2-ethylhexyl) phthalate and di-n-butyl phthalate dominated in the 11 PAEs, with the average values of 0.735 and 1.915 μg g^?1, respectively, and accounted for 92.1 % of the whole PAEs’ concentrations. No significant differences of PAE congeneric profiles were observed between our work and others previously reported, which is consistent with the use of similar commercial PAEs around the world.     

Monitoring of soil and groundwater contamination following a pipeline explosion and petroleum product spillage in Ijegun, Lagos Nigeria

In May 2008, an accidental damage of a Nigerian National Petroleum Corporation (NNPC) pipeline occurred in Ijegun area of Lagos, Nigeria, resulting in oil spillage and consequent contamination of the environment. The residual concentration of the total hydrocarbon (THC) and benzene, toluene, ethylbenzene, and xylene (BTEX) in the groundwater and soil was therefore investigated between March 2009 and July 2010. Results showed elevated THC mean levels in groundwater which were above the World Health Organization maximum admissible value of 0.1 mg/l. THC values as high as 757.97 mg/l in groundwater and 402.52 mg/l in soil were observed in March 2009. Pronounced seasonal variation in the concentration of THC in groundwater and soil samples show that there was significant (P?<?0.05) difference in the measured concentration of THC between each season (dry and wet), with the highest being in the dry season and between the years 2009 and 2010. Significant hydrocarbon contamination, 500 m beyond the explosion site and 25 months after the incident, was observed revealing the extent of the spillage of petroleum products. The highest concentrations of 16.65 μg/l (benzene), 2.08 μg/l (toluene), and 4864.79 μg/l (xylene) were found in stations within the 100 m buffer zone. Most of the samples of groundwater taken were above the target value of 0.2 μg/l set for BTEX compounds by the Environmental Guidelines and Standards for Petroleum Industry in Nigeria. The level of hydrocarbon in the impacted area calls for concern and remediation of the area is urgently needed to reduce further negative impact on the ecosystem.     

Effect of elevated CO2 on degradation of azoxystrobin and soil microbial activity in rice soil

An experiment was conducted in open-top chambers (OTC) to study the effect of elevated CO₂ (580?±?20 μmol mol^?1) on azoxystrobin degradation and soil microbial activities. Results indicated that elevated CO₂ did not have any significant effect on the persistence of azoxystrobin in rice-planted soil. The half-life values for the azoxystrobin in rice soils were 20.3 days in control (rice grown at ambient CO₂ outdoors), 19.3 days in rice grown under ambient CO₂ atmosphere in OTC, and 17.5 days in rice grown under elevated CO₂ atmosphere in OTC. Azoxystrobin acid was recovered as the only metabolite of azoxystrobin, but it did not accumulate in the soil/water and was further metabolized. Elevated CO₂ enhanced soil microbial biomass (MBC) and alkaline phosphatase activity of soil. Compared with rice grown at ambient CO₂ (both outdoors and in OTC), the soil MBC at elevated CO₂ increased by twofold. Elevated CO₂ did not affect dehydrogenase, fluorescein diacetate, and acid phosphatase activity. Azoxystrobin application to soils, both ambient and elevated CO₂, inhibited alkaline phosphates activity, while no effect was observed on other enzymes. Slight increase (1.8–2 °C) in temperature inside OTC did not affect microbial parameters, as similar activities were recorded in rice grown outdoors and in OTC at ambient CO₂. Higher MBC in soil at elevated CO₂ could be attributed to increased carbon availability in the rhizosphere via plant metabolism and root secretion; however, it did not significantly increase azoxystrobin degradation, suggesting that pesticide degradation was not the result of soil MBC alone. Study suggested that increased CO₂ levels following global warming might not adversely affect azoxystrobin degradation. However, global warming is a continuous and cumulative process, therefore, long-term studies are necessary to get more realistic assessment of global warming on fate of pesticide.     

Perchlorate contamination of groundwater from fireworks manufacturing area in South India

Perchlorate contamination was investigated in groundwater and surface water from Sivakasi and Madurai in the Tamil Nadu State of South India. Sensitive determination of perchlorate (LOQ?=?0.005 μg/L) was achieved by large-volume (500 μL) injection ion chromatography coupled with tandem mass spectrometry. Concentrations of perchlorate were <0.005–7,690 μg/L in groundwater (n?=?60), <0.005–30.2 μg/L in surface water (n?=?11), and 0.063–0.393 μg/L in tap water (n?=?3). Levels in groundwater were significantly higher in the fireworks factory area than in the other locations, indicating that the fireworks and safety match industries are principal sources of perchlorate pollution. This is the first study that reports the contamination status of perchlorate in this area and reveals firework manufacture to be the pollution source. Since perchlorate levels in 17 out of 57 groundwater samples from Sivakasi, and none from Madurai, exceeded the drinking water guideline level proposed by USEPA (15 μg/L), further investigation on human health is warranted.