Effects of the organophosphorus insecticide fenthion on phyto- and zooplankton communities in experimental ponds

The organophosphorus insecticide fenthion was applied to experimental ponds and its effects on phyto- and zooplankton communities were analysed. The sensitivity to fenthion differed among cladoceran and rotiferan species according to the following order: Daphnia galeata > Monia micrura > Bosmina fatalis >/= Polyarthra trigla > Keratella valga. The results suggest that large zooplankton species tend to be more sensitive to fenthion than small ones, large cladocerans more sensitive than small cladocerans, and cladocerans more sensitive than rotifers. The application of fenthion induced an increase in the density of rotifers and phytoplankton. This was a secondary effect of the chemical, which directly depressed cladoceran populations and consequently released rotifers and phytoplankton from competition with, and grazing by cladocerans.     

Iron speciation and hydrogen peroxide concentrations in New Zealand rainwater

Rain was collected on the southern portion of the South Island of New Zealand during the summer of 1999 (January–March) during which time significant losses of ozone and increased UV were reported in the stratosphere over New Zealand. Iron and hydrogen peroxide concentrations were measured in rainwater because these analytes are directly influenced by photochemical processes and therefore are particularly susceptible to increasing UV levels. The absolute concentration of dissolved Fe(II) in New Zealand samples was very similar to summertime rain received in Wilmington, NC however the relative contribution of Fe(II) to total Fe was approximately twice as great in New Zealand samples. The larger percentage of reduced iron may reflect higher UV levels in New Zealand since Fe(II) is generated via photochemical reduction of particulate or dissolved Fe(III). No dissolved Fe(III) was detected in New Zealand rainwater, in contrast to the Wilmington site, where summertime Fe(III) concentrations are approximately equal to Fe(II) concentrations. Summertime hydrogen peroxide concentrations and diel variability in New Zealand were similar to other coastal and marine values in both the northern and southern hemispheres suggesting the increasing UV in New Zealand is not significantly increasing hydrogen peroxide concentrations at this location. Any excess photochemically produced hydrogen peroxide in New Zealand may be consumed through oxidation of Fe(II) which is rapidly reformed from photochemical reduction of Fe(III) by the higher UV levels in New Zealand.     

Acetylcholinesterase-polyaniline biosensor investigation of organophosphate pesticides in selected organic solvents

The behavior of an amperometric organic-phase biosensor consisting of a gold electrode modified first with a mercaptobenzothiazole self-assembled monolayer, followed by electropolymerization of polyaniline in which acetylcholinesterase as enzyme was immobilized, has been developed and evaluated for organophosphorous pesticide detection. The voltammetric results have shown that the formal potential shifts anodically as the Au/MBT/PANI/AChE/PVAc thick-film biosensor responded to acetylthiocholine substrate addition under anaerobic conditions in selected organic solvent media containing 2% v/v 0.05 M phosphate buffer, 0.1 M KCl (pH 7.2) solution. Detection limits in the order of 0.147 ppb for diazinon and 0.172 ppb for fenthion in acetone-saline phosphate buffer solution, and 0.180 ppb for diazinon and 0.194 ppb for fenthion in ethanol-saline phosphate buffer solution has been achieved.     

The New Zealand experience of varroa invasion highlights research opportunities for Australia

The Varroa mite (Varroa destructor) is implicated as a major disease factor in honey bee (Apis mellifera) populations worldwide. Honey bees are extensively relied upon for pollination services, and in countries such as New Zealand and Australia where honey bees have been introduced specifically for commercial pollinator services, the economic effects of any decline in honey bee numbers are predicted to be profound. V. destructor established in New Zealand in 2000 but as yet, Australia remains Varroa-free. Here we analyze the history of V. destructor invasion and spread in New Zealand and discuss the likely long-term impacts. When the mite was discovered in New Zealand, it was considered too well established for eradication to be feasible. Despite control efforts, V. destructor has since spread throughout the country. Today, assessing the impacts of the arrival of V. destructor in this country is compromised by a paucity of data on pollinator communities as they existed prior to invasion. Australia’s Varroa-free status provides a rare and likely brief window of opportunity for the global bee research community to gain understanding of honey bee-native pollinator community dynamics prior to Varroa invasion.     

A bottom-up clustering approach to identify bus driving patterns and to develop bus driving cycles for Hong Kong

Bus transport has been an important mode taking up a significant share of urban travel demand and thus the corresponding impacts on the environment are of great concerns. Use of driving cycles to evaluate the environmental impacts of buses has attracted much attention in recent years worldwide. The franchised bus service is currently playing important roles in the public transport system in Hong Kong; however, there is no driving cycle developed specifically for them. A set of bus driving cycle was therefore developed using a bottom-up approach where driving data on the bus network with mixed characteristics were collected. Using the Ward’s method for clustering, the collected data were then categorized into three clusters representing distinct franchised bus route patterns in Hong Kong. Driving cycles were then developed for each route pattern including (i) congested urban routes with closely spaced bus stops and traffic junctions; (ii) inter-district routes containing a number of stop-and-go activities and a significant portion of smoother high speed driving; and (iii) early morning express routes and mid-night routes connecting remote residential areas and urban areas. These cycles highlighted the unique low-speed and aggressive driving characteristics of bus transport in Hong Kong with frequent stop-and-go activities. The findings from this study would definitely be helpful in assessing the exhaust emissions, fuel consumptions as well as energy consumptions of bus transport. The bottom-up clustering approach adopted in this study would also be useful in identifying specific driving patterns based on vehicle speed trip data with mixed driving characteristics. It is believed that this approach is especially suitable for assessing fixed route public transport modes with mixed driving characteristics.

     

Synthesis of halogenated diphenyl ethers and dibenzofurans - A discussion of specific isomers available

Synthetic routes for the preparation of halogenated diphenyl ethers and dibenzofurans are reviewed, and isomers reported in the literature are listed. In addition, the routes preferred for the synthesis of specific chlorinated isomers - especially from the point of view of an unambiguous structural assignment - are discussed in detail. The route recommended for chlorinated diphenyl ethers is the coupling of biaryliodonium salts with phenols, and for chlorinated dibenzofurans the palladium acetate-promoted cyclization of diphenyl ethers. Chlorinated isomers of diphenyl ethers and dibenzofurans which are available via these routes are listed. Furthermore, the synthesis of a new octachlorodiphenyliodonium salt and its coupling with three different chlorophenols are described, and the cyclization of an octachlorodiphenyl ether to octachlorodibenzofuran is shown.     

Monitoring land-use change effects on soil carbon in New Zealand: quantifying baseline soil carbon stocks

We designed a soil carbon monitoring system for New Zealand using country-specific land use and soil carbon information. The system pre-stratifies the country by soil type, climate, and land use. Soils were placed in six IPCC soil categories; Podzols were added as they are widespread throughout New Zealand. Temperature was stratified into two categories, each spanning 7 degrees C. Moisture categories were based on water balance, and included five categories. Temperature and moisture stratification was based on the USDA Soil Classification system. Land use (10 categories) was based on 1980s survey data. Overall, 39 combinations of these three factors (cells) described 93% of the New Zealand landscape. Geo-referenced soil carbon data (carbon concentration and bulk density) were used to quantify average soil carbon for each of the 39 cells. Aggregating the polygons gave an estimated 1990 soil carbon baseline of 1152+/-44, 1439+/-73, and 1602+/-167 Mt C (mean+/-S.D.) for the 0-0.1, 0.1-0.3, and 0.3-1.0 m depth increments (not including forest floor carbon). The system described could also be used to quantify equilibrium changes in soil C associated with land-use change if land use is updated periodically.     

Clinical and toxicological data in Fenthion and omethoate acute poisoning

Abstract

This study paper reports on two cases of poisoning with the organophosphorus insecticides, fenthion and omethoate. The two victims were admitted in the Intensive Care Unit (ICU) a few hours after ingestion of the two insecticides. They received appropriate treatment for organophosphorous poisoning (gastric lavage, activated charcoal, atropine and pralidoxime) and supportive care. Both patients survived. Organophosphate blood levels were determined on admission (fenthion 2.9 (ig/ml, omethoate 1.6 Hg/ml) and during the hospitalisation and proved to be considerably high. Slow elimination rate of the poison already distributed in the body was indicated for both pesticides. The patient with omethoate poisoning remained clinically well (Glasgow Coma Scale : 15) and was discharged three days later. The patient with fenthion poisoning, who had also ingested 30 mg of bromazepam and 720 mg of oxetoron, developed cholinergic crisis six hours after admission and was intubated for 24 days, with concomitant complications.     

Heterogeneous reactions of suspended parathion, malathion, and fenthion particles with NO(3) radicals

Organophosphorus pesticides (OPPs) emit into the atmosphere in both gas and particulate phases via spray drift from treatments and post-application emission, but most of their degradations in the atmosphere are not well known. In this study, the heterogeneous reactions of nitrate (NO₃) radicals with three typical OPPs (parathion, malathion, and fenthion) absorbed on azelaic acid particles are investigated using an online vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The reaction products observed with the VUV-ATOFMS are identified on the basis of GC/MS analysis of the products in the reaction between NO₃ radicals and the coating of the pesticide. Paraoxon is identified as the only product of parathion; malaoxon and bis(1,2-bis-ethoxycarbonylethyl)disulfide as the products of malathion; fenoxon, fenoxon sulfoxide, fenthion sulfoxide, fenoxon sulfone, and fenthion sulfone as the products of fenthion. The degradation rates of parathion, malathion, and fenthion under the experimental conditions are 5.5 × 10⁻³, 5.6 × 10⁻², and 3.3 × 10⁻² s⁻¹, respectively. The pathways of the heterogeneous reactions between the three OPPs and NO₃ radicals are proposed. The experimental results reveal the possible transformations of these OPPs through the oxidation of NO₃ radicals in the atmosphere.     

Uptake,distribution and elimination of monosodium methanearsonate following long term oral administration of the herbicide to sheep and goats

Abstract

The rate and extent of accumulation and washout of arsenic, during daily oral administration of the herbicide monosodium methanearsonate (MSMA) were evaluated in Iranian dairy sheep and goats. Subjects received a dose of 10 mg of MSMA as arsenic per kg of body weight daily for 28 consecutive days. The total arsenic concentration in blood and milk was measured during and after the period of MSMA administration while arsenic in urine and feces was measured for 10 days following administration of last dosage of MSMA.

Arsenic was accumulated slowly during 28 days of MSMA administration and steady states were essentially complete in sheep after 20 days and in goats following 25 days of MSMA administration. Blood arsenic concentration decreased rapidly after termination of MSMA administration. In both test animals, the half‐lives of washout were smaller than accumulation. The concentration of arsenic in the urine and feces of both species did not increase significantly over controls and animals were free of arsenic relatively shortly after administration stopped.

These data indicate that arsenic from MSMA is mainly absorbed from gastrointestinal tract and is not significantly accumulated in the body. Arsenic is eliminated from body by way of urine and feces with urinary excretion being the most important route.     

A method for the analysis of organophosphorus pesticide residues in Mexican axolotl

A method based on matrix solid-phase dispersion (MSPD) was developed for quantitative extraction of three organophosphorus pesticides (OPPs) from the Mexican axolotl, Ambystoma mexicanum. The determination was carried out using high- performance liquid chromatography (HPLC) with diode array spectrophotometric UV detection (DAD). The MSPD extraction with octadecylsilyl (C18) sorbent combined with a silica gel clean-up and acetonitrile elution was optimised for chlorpyrifos, fenthion and methyl parathion. The method was validated, yielding recovery values higher than 90%. The precision, expressed as the relative standard deviation (RSD), was less than or equal to 6% in muscle samples at spiking levels of 10 and 5 ppm. Linearity was studied from 15 to 60 ppm for chlorpyrifos and fenthion, and from 7.5 to 30 ppm for methyl parathion. The limits of detection (LODs) were found to be less than or equal to 0.5 ppm_.This method was applied to the analysis of samples from a chlorpyrifos-exposed axolotl, demonstrating its use as an analytical tool for toxicological studies.     

Comparision of the waterborne and dietary routes of exposure on the effects of Benzo(a)pyrene on biotransformation pathways in Nile tilapia (Oreochromis niloticus)

BaP is one of the most studied PAH, due to its ubiquitous presence in aquatic environments and toxicity to aquatic organisms. The main goal of this study was to assess BaP effects in Nile Tilapia after waterborne and dietary exposures, through the evaluation of EROD and GST activities in liver, gills and intestine, and BaP metabolites in bile; and also to evaluate the usefulness of these commonly used biomarkers after two different routes of exposure. Waterborne exposure to BaP led to a significant induction of EROD in all tissues analyzed (644%, 1640% and 2880% in relation to solvent in liver, gill and intestine respectively) while in dietary exposures EROD was induced only in intestine (3143%) after exposure to high BaP concentrations. GST activities with CDNB were slightly induced in liver (40%) and in gill (66%) after water exposure to BaP, and in intestine after dietary exposure to low BaP concentrations (182%). BaP metabolites in bile increased after both exposure routes, and were highly correlated with EROD activity after water exposure. In summary, this work has shown that the effects of BaP on biotransformation pathways depend on the route of exposure. Moreover, barrier tissues like gills and intestine also have an important role in the first-pass metabolism of BaP, reducing the amount of parent compound that reaches the liver to be metabolized. For that reason, EROD activity as a biomarker of exposure should also be applied in extrahepatic organs, like gills and intestine, in monitoring studies. Biliary BaP type metabolites are good reflectors of contamination levels under both exposure routes, while GST activity with CDNB as substrate, as a phase II enzyme, does not seem a reliable biomarker of exposure to BaP regardless the route of exposure.     

Regional variation of selected polyaromatic and chlorinated hydrocarbons over the South Island of New Zealand, as indicated by their content in Pinus radiata needles

We analysed needles of Pinus radiata along three transects through the South Island of New Zealand for chlorinated hydrocarbons ( alpha- and gamma-HCH, HCB and PCB) and PAH (fluoranthene, 3,4-benzopyrene, benzo(ghi)perylene and indenopyrene). At rural sites we also collected samples of moss (Wijkia extenuata) and lichens (Usnea sp.) in order to compare the pollutant concentrations within these plants. A principal component analysis confirmed findings from moss and snow studies in Europe that the PAH concentrations vary regionally in the same way. The pattern of the principal component loadings of the chlorinated hydrocarbons reflects their heterogeneous immission and their different chemodynamics. The regional pattern indicates an increase of gamma-HCH from remote areas to those used intensively for agriculture and gardening, followed by a decrease towards the inner city of Christchurch. In contrast, PCB and PAH show their highest levels of contamination in the city. The regional distribution of PAH in Christchurch correlates well with traffic density, and particularly with the pattern of smoke from domestic fires. Our study demonstrates that needles of P. radiata can be better monitors of atmospheric pollution in New Zealand than mosses or lichens.     

Predicting groundwater nitrate concentrations in a region of mixed agricultural land use: a comparison of three approaches.

We investigated whether nitrate-N (NO3(-)-N) concentrations of shallow groundwater (< 30 m from the land surface) in a region of intensive agriculture could be predicted on the basis of land use information, topsoil properties that affect the ability of topsoil to generate nitrate at a site, or the 'leaching risk' at different sites. Groundwater NO3(-)-N concentrations were collected biannually for 3 years at 88 sites within the Waikato Region of New Zealand. The land use was classed as either the predominant land use of the farm where the well or bore was located, or the dominant land use within a 500 m radius of the well or bore. Topsoil properties that affect the ability of soil to generate nitrate were also measured at all the sites, and a leaching risk assessment model 'DRASTIC' was used to assess the risk of NO3(-)-N leaching to groundwater at each site. The concentration of NO3(-)-N in shallow groundwater in the Waikato Region varied considerably, both temporally and spatially. Nine percent of sites surveyed had groundwater NO3(-)-N concentrations exceeding maximum allowable concentrations of 11.3 ppm recommended by the World Health Organisation for potable drinking water which is accepted as a public health standard in New Zealand. Over half (56%) of the sites had concentrations that exceeded 3 ppm, indicating effects of human activities (commonly referred to as a human activity value). Very few trends in NO3(-)-N concentration that could be attributed to land use were identified, although market garden sites had higher concentrations of NO3(-)-N in underlying groundwater than drystock/sheep sites when the land use within 500 m radius of a sampling site was used to define the land use. There was also some evidence that within a district, NO3(-)-N concentrations in groundwater increased as the proportion of area used for dairy farming increased. Compared to pastoral land, market gardens had lower total C and N, potentially mineralisable N and denitrifying enzyme assay. However, none of these soil properties were directly related to groundwater NO3(-)-N concentrations. Instead, the DRASTIC index (which ranks sites according to their risk of solute leaching) gave the best correlation with groundwater NO3(-)-N concentrations. The permeability of the vadose zone was the most important parameter. The three approaches used were all considered unsuitable for assessing nitrate concentrations of groundwater, although a best-fit combination of parameters measured was able to account for nearly half the variance in groundwater NO3(-)-N concentrations. We suggest that non-point source groundwater NO3(-)-N contamination in the region reflects the intensive agricultural practices, and that localised, site-specific, factors may affect NO3(-)-N concentrations in shallow groundwaters as much as the general land use in the surrounding area.     

The role of carbonate radical in limiting the persistence of sulfur-containing chemicals in sunlit natural waters

Carbonate radical (*CO3-) is a selective oxidant that may be important in limiting the persistence of a number of sulfur-containing compounds in sunlit natural waters. Thioanisole, dibenzothiophene (DBT), and fenthion were selected to investigate the degradation pathway initiated by *CO3-; electron-rich sulfur compounds are particularly reactive towards the *CO3-. Using HPLC, GC, GC-MS and LC-MS for structural confirmation, the major photodegradation products of thioanisole and DBT were the corresponding sulfoxides. The sulfoxide products were further oxidized through reaction with *CO3- to the corresponding sulfone derivatives. Fenthion showed a similar pathway with appearance of fenthion sulfoxide as the major product. The proposed mechanism involves abstraction of an electron on sulfur to form a radical cation, which is then oxidized by dissolved oxygen. Each of the sulfur probes were further investigated in a sunlight simulator under varying matrix conditions. The highest rate constants occurred in the *CO3- matrix, and the lowest occurred in a matrix of dissolved organic carbon (DOC) and bicarbonate. In synthetic and natural field water, thioanisole photodegraded faster than under direct photolysis, with half-lives of 75.1 and 85.8 min, respectively. Fenthion photodegraded more rapidly than thioanisole. DBT photodegraded rapidly in a *CO3- matrix with a half-life of 24.8 min, while the half-life of direct photolysis was 350 min. Photodegradation products of each compound were also investigated. Ultimately, *CO3- was found to contribute toward the photodegradation of sulfur-containing compounds in natural waters.     

Site-specific water quality guidelines: 1. Derivation approaches based on physicochemical, ecotoxicological and ecological data

Generic water quality guidelines (WQGs) are developed by countries/regions as broad scale tools to assist with the protection of aquatic ecosystems from the impacts of toxicants. However, since generic WQGs cannot adequately account for the many environmental factors that may affect toxicity at a particular site, site-specific WQGs are often needed, especially for high environmental value ecosystems. The Australian and New Zealand Guidelines for Fresh and Marine Water Quality provide comprehensive guidance on methods for refining or deriving WQGs for site-specific purposes. This paper describes three such methods for deriving site-specific WQGs, namely: (1) using local reference water quality data, (2) using biological effects data from laboratory-based toxicity testing, and (3) using biological effects data from field surveys. Two case studies related to the assessment of impacts arising from mining operations in northern Australia are used to illustrate the application of these methods. Finally, the potential of several emerging methods designed to assess thresholds of ecological change from field data for deriving site-specific WQGs is discussed. Ideally, multiple lines of evidence approaches, integrating both laboratory and field data, are recommended for deriving site-specific WQGs.     

Low levels of persistent organic pollutants (POPs) in New Zealand eels reflect isolation from atmospheric sources

Polychlorinated biphenyls (PCBs) and organic pesticides (i.e., DDTs) were measured in long finned eels (Anguilla dieffenbachii) in 17 streams on the west coast of South Island, New Zealand. Very low levels of PCBs and low levels of ppDDE were found. The concentrations of PCBs and ppDDE were not correlated within sites indicating that different processes determined the levels of the two pollutants in New Zealand eels. The PCBs probably originate from atmospheric transport, ppDDE levels are determined by land use and are higher in agriculture areas. The low contamination level of these aquatic systems seems to be a function of a low input from both long and short-range transport as well as few local point sources. No correlation could be found between lipid content and persistent organic pollutants (POPs) concentration (as shown in previous studies) in the eels which could be explained by low and irregular intake of the pollutants.     

Towards a renewed research agenda in ecotoxicology

New concerns about biodiversity, ecosystem services and human health triggered several new regulations increasing the need for sound ecotoxicological risk assessment. The PEER network aims to share its view on the research issues that this challenges. PEER scientists call for an improved biologically relevant exposure assessment. They promote comprehensive effect assessment at several biological levels. Biological traits should be used for Environmental risk assessment (ERA) as promising tools to better understand relationships between structure and functioning of ecosystems. The use of modern high throughput methods could also enhance the amount of data for a better risk assessment. Improved models coping with multiple stressors or biological levels are necessary to answer for a more scientifically based risk assessment. Those methods must be embedded within life cycle analysis or economical models for efficient regulations. Joint research programmes involving humanities with ecological sciences should be developed for a sound risk management.     

Persistent organochlorines in the serum of the non-occupationally exposed New Zealand population

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and organochlorine pesticides were measured in the serum of a sample of the New Zealand population aged 15 years and older. This was the first study to obtain representative measures of PCDDs, PCDFs and PCBs in the adult population of an entire country. Serum samples were obtained in 1996-1997. Potentially occupationally exposed individuals were excluded. Serum samples were pooled according to stratification criteria for area of residence, ethnicity, age, and sex. Of the 80 possible strata, sufficient serum for chemical analysis was available for 60, to which 1,834 individual samples contributed. For the PCDDs and PCDFs, most 2,3,7,8-chlorinated congeners were measured in all strata, with a mean toxic equivalents concentration across all strata of 12.8 ng TEQ kg(-1) lipid. Seven PCB congeners were frequently measured, including the coplanar congeners #126 and #169, quantified in all strata. Of the pesticides and their metabolites, only beta-HCH, dieldrin and pp'-DDE were consistently detected across strata. There was a general trend of increasing concentration with age. There were no consistent differences between the sexes, or between people of Maori (the indigenous people of New Zealand) and non-Maori ethnicity. Concentrations of PCDDs and PCDFs tended to increase in a North-South direction, possibly reflecting greater levels of industrialization and population concentration, and concentrations of the pesticide products were highest in the South, possibly reflecting historical use patterns. Results were consistent with a recent study of concentrations of these compounds in the milk of first-time mothers.     

Accumulation and excretion of organophosphorous pesticides by willow shiner

Bioconcentration and excretion of 8 organophosphorous pesticides were studied for willow shiner ( ). The average bioconcentration factors (BCF) in the whole body of the fish after 24 – 168 hr exposure were 0.8 for dichlorvos, 76 for salithion, 18 for methidathion, 29 for pyridaphenthion, 481 for fenthion and 36 for phosmet, Further, the BCF values of the other pesticides after 168 hr exposure were 713 for phenthoate and 1682 for EPN. The correlation between n-octanol-water partition coefficients (P_OW) and BCF in willow shiner was investigated for 19 pesticides studied here and already reported. The correlation factor (r) was not so high (0.6819, n=19) but higher (0.9085, n=18) in case excluding captan. The excretion rate constants (k) from the whole body of willow shiner were 0.20 hr⁻¹ for salthion, 0.05 hr⁻¹ for phenthoate, 0.27 hr⁻¹ for methidathion, 0.20 hr⁻¹ for pyridaphenthion, 0.07 hr⁻¹ for fenthion, 0.04 hr⁻¹ for EPN and 0.28 hr⁻¹ for phosmet.