Effects of long-term chlorpyrifos exposure on mortality and reproductive tissues of Banded Gourami (Trichogaster fasciata)

Abstract

This study assessed the long-term toxicity of chlorpyrifos on survival and reproduction of Banded Gourami by using mortality, gonado-somatic index (GSI) and histopathological observations as endpoints. Adult fish were exposed to five different concentrations of chlorpyrifos (0, 15, 50, 150, 500?µg/L) in 15 PVC tanks for 15, 30, 45, 60 and 75?days. Results showed that all male and female fish died after 15?days of 500?µg/L chlorpyrifos exposure. No consistent significant effect was observed for both male and female GSI. Furthermore, results showed dose- and time-dependent histopathological alterations for both ovary and testes. The 60-d No Observed Effect Concentration (NOEC) for most histopathological alterations of Banded Gourami ovary and testes was 50?μg/L, while 60-d NOEC for mortality of both male and female fish was < 15?μg/L. The results show that the long-term exposure to chlorpyrifos not only affect the reproductive tissues of Banded Gourami at exposure concentrations but also cause their mortality. Future studies should evaluate effects at lower concentrations.     

Agricultural Chemicals in the Alluvial Aquifer of a Typical County of the Arkansas Delta

Statistical methods and a Geographic Information System (GIS) were used to investigate potential indicators of ground water vulnerability to agricultural chemical contamination in a representative area of the Mississippi River alluvial aquifer. A total of 47 wells were sampled for analysis of nitrate, phosphorus, potassium, and 13 pesticides commonly-used in the area. Ten soil and hydrogeologic variables and five ground water vulnerability indices were examined to explain the variations of chemical concentrations. The results showed that no individual soil or hydrogeologic variables or their linear combinations could explain more than 25% of the variation of the chemical concentrations. A quadratic response surface model with the values of confining unit thickness, slope, soil permeability, depth to ground water, and recharge rate accounted for 62% of the variation of nitrate, 43% of P, and 83% of K, suggesting that the interactions among soil and hydrogeologic variables were significant. Observed trends of decreasing nitrate and P concentrations with increasing well depth and/or depth to ground water seemed to correlate with carbonate equilibrium in the aquifer and more reduced environment with depth. In view of uncertainties involved, it was recognized that the limitations associated with input data resolution used in GIS and the formulation of leaching indices limited their use for predicting ground water vulnerability. Misuse of pesticides could be another factor that would complicate the relationships between pesticide concentrations and the vulnerability indices.     

水样中有机磷的微波消解

采用微波消解系统对水样中有机磷进行消解，考察了消解时间、功率等不同实验条件对样品微波消解的影响；并将该法与总磷测定的常规消解方法进行了比较，结果表明，微波消解法简便、快速、准确、可靠     

Effects of different treatments on soil-borne DDT and HCH dynamics and plant uptake

Pot experiments were conducted to examine the effects of various fertilizers, as well as soil dilution treatments on the dynamics of soil-borne DDTs [sum of dichlorodiphenyltrichloroethane (DDT), chlorodiphenyldichloroethylene (DDE) and di- chlorodiphenyldichloroethane (DDD)] and hexachlorocyclohexanes (HCHs, sum of α-HCH, β-HCH, γ-HCH and δ-HCH) and their subsequent impacts on the uptake of DDTs and HCHs by a test plant. The results show that the soil residual DDTs and HCHs concentrations in the iron-rich fertilizer-treated soil were significantly lower than those in other fertilizer-treated soils. There was a close relationship between the soil residual DDTs and the plant tissue DDTs. This suggests that the uptake rate of DDTs by the plant was dependent on the concentration of soil-borne DDTs. A less close relationship between soil residual HCHs and plant tissue HCHs was also observed. Dilution of pesticide-contaminated soil with the non-contaminated soil not only physically reduced the concentration of pesticides in the soil but also enhanced the loss of soil-borne pesticides, possibly through the improvement of soil conditions for microbial degradation. Soil dilution had a better effect on promoting the loss of soil-borne HCHs, relative to soil-borne-DDTs. The research findings obtained from this study have implications for management of heavily contaminated soils with DDTs and HCHs. Remediation of DDTs and HCHs-contaminated soils in a cost-effective way can be achieved by incorporating treatment techniques into conventional agricultural practices. Applications of iron-rich fertilizer and soil dilution treatments could cost-effectively reduce soil-borne DDTs and HCHs, and subsequently the uptake of these organochlorine pesticides by vegetables.     

Acute and chronic toxicity of organophosphate monocrotophos to Daphnia magna

The acute and chronic toxicity of monocrotophos (MCP), the binary joint toxicity of MCP and bifenthrin (BF), and sodium dodecyl benzene sulfonate (SDBS) to Daphnia magna (D. magna) was evaluated. The 24 h-median effective concentration (24 h-EC₅₀) and 48 h-median lethal concentration (48 h-LC₅₀) of MCP towards D. magna were 161 and 388 μ g/L, respectively. In addition, the lowest-observed effective concentration (LOEC) and non-observed effective concentration (NOEC) of MCP to D. magna were 10 and 5 μ g/L, respectively. Furthermore, the chronic value (ChV) of MCP against D. magna was 7 μ g/L and the acute chronic ratio (ACR) was 55. The number of offspring per female and the intrinsic rate of natural increase (r) were identified as the parameters that were most sensitive to MCP. In addition, toxic unit (TU) analysis was employed to evaluate the joint toxicities. The calculated TU_mix values of binary equitoxic mixtures of MCP + BF and MCP + SDBS were 1.47 and 1.63, respectively, which suggests that both equitoxic mixtures exert a limited antagonistic effect. The results of this study revealed that the toxic threshold of MCP towards D. magna is higher than its reported highest residue (4 μ g/L) in the ordinary aquatic environment, and that concurrent exposure to BF or SDBS may exert a slight antagonistic effect.     

Effect of Widespread Agricultural Chemical Use on Butterfly Diversity across Turkish Provinces

Although agricultural intensification is thought to pose a significant threat to species, little is known about its role in driving biodiversity loss at regional scales. I assessed the effects of a major component of agricultural intensification, agricultural chemical use, and land‐cover and climatic variables on butterfly diversity across 81 provinces in Turkey, where agriculture is practiced extensively but with varying degrees of intensity. I determined butterfly species presence in each province from data on known butterfly distributions and calculated agricultural chemical use as the proportion of agricultural households that use chemical fertilizers and pesticides. I used constrained correspondence analyses and regression‐based multimodel inference to determine the effect of environmental variables on species composition and richness, respectively. The variation in butterfly species composition across the provinces was largely explained (78%) by the combination of agricultural chemical use, particularly pesticides, and climatic and land‐cover variables. Although overall butterfly richness was primarily explained by climatic and land‐cover variables, such as the area of natural vegetation cover, threatened butterfly richness and the relative number of threatened butterfly species decreased substantially as the proportion of agricultural households using pesticides increased. These findings suggest that widespread use of agricultural chemicals, or other components of agricultural intensification that may be collinear with pesticide use, pose an imminent threat to the biodiversity of Turkey. Accordingly, policies that mitigate agricultural intensification and promote low‐input farming practices are crucial for protecting threatened species from extinction in rapidly industrializing nations such as Turkey. Efectos del Uso Extensivo de Agroquímicos sobre la Diversidad de Mariposas en Provincias Turcas     

Metolachlor and chlorothalonil dissipation in gypsum-amended soil

This work focused on the interactive effects of the fungicide chlorothalonil (2,3,4,6-tetrachloro-1,3-benzendicarbonitrile) and gypsum on the persistence of the soil-residual herbicide metolachlor (2-chloro-N-(6-ethyl-o-tolyl)-N-[(1RS)-2-methoxy-1-methylethyl]acetamide). Gypsum application was included due to its widespread use on peanut (Arachis hypogaea). Both agricultural grade gypsum and reagent CaSO₄-2H₂O were tested. A laboratory soil incubation was conducted to evaluate interactive effects. Results indicated 1.5X greater metolachlor half-life (DT₅₀) in soil amended with chlorothalonil (37 d) as compared to control soil (25 d). The two gypsum sources alone increased metolachlor DT₅₀ to about 32 d and with the combination of chlorothalonil and gypsum, DT50 was 50 d, 2-fold greater than the control. Chlorothalonil dissipation was rapid (DT₅₀ < 4d). A possible explanation for metolachlor dissipation kinetics is a build-up of the chlorothalonil intermediate (4-hydroxychlorothalonil) which limited soil microbial activity and depleted glutathione S-transferase (GST) from chlorothalonil detoxification. Further information related to gypsum impacts is needed. Results confirm previous reports of chlorothalonil impeding metolachlor dissipation and showed the gypsum application extended persistence even longer. Farming practices, such as reducing metolachlor application rates, may need to be adjusted for peanut cropping systems where chlorothalonil and gypsum are used.     

Lethal Effects of Water Quality on Threatened California Salamanders but Not on Co‐Occurring Hybrid Salamanders

Biological invasions and habitat alteration are often detrimental to native species, but their interactions are difficult to predict. Interbreeding between native and introduced species generates novel genotypes and phenotypes, and human land use alters habitat structure and chemistry. Both invasions and habitat alteration create new biological challenges and opportunities. In the intensively farmed Salinas Valley, California (U.S.A.), threatened California tiger salamanders (Ambystoma californiense) have been replaced by hybrids between California tiger salamander and introduced barred tiger salamanders (Ambystoma tigrinum mavortium). We conducted an enclosure experiment to examine the effects habitat modification and relative frequency of hybrid and native California tiger salamanders have on recruitment of salamanders and their prey, Pacific chorus frogs (Pseudacris regilla). We tested whether recruitment differed among genetic classes of tiger salamanders (hybrid or native) and pond hydroperiod (seasonal or perennial). Roughly 6 weeks into the experiment, 70% (of 378 total) of salamander larvae died in 4 out of 6 ponds. Native salamanders survived (n = 12) in these ponds only if they had metamorphosed prior to the die‐offs. During die‐offs, all larvae of native salamanders died, whereas 56% of hybrid larvae died. We necropsied native and hybrid salamanders, tested water quality, and queried the California Department of Pesticide Regulation database to investigate possible causes of the die‐offs. Salamander die‐offs, changes in the abundance of other community members (invertebrates, algae, and cyanobacteria), shifts in salamander sex ratio, and patterns of pesticide application in adjacent fields suggest that pesticide use may have contributed to die‐offs. That all survivors were hybrids suggests that environmental stress may promote rapid displacement of native genotypes. Efectos Letales de la Calidad del Agua sobre Salamandras de California Amenazadas pero no sobre Salamandras Híbridas Concurrentes     

Review on the use of enzymes for the detection of organochlorine, organophosphate and carbamate pesticides in the environment

Pesticides are released intentionally into the environment and, through various processes, contaminate the environment. Three of the main classes of pesticides that pose a serious problem are organochlorines, organophosphates and carbamates. While pesticides are associated with many health effects, there is a lack of monitoring data on these contaminants. Traditional chromatographic methods are effective for the analysis of pesticides in the environment, but have limitations and prevent adequate monitoring. Enzymatic methods have been promoted for many years as an alternative method of detection of these pesticides. The main enzymes that have been utilised in this regard have been acetylcholinesterase, butyrylcholinesterase, alkaline phosphatase, organophosphorus hydrolase and tyrosinase. The enzymatic methods are based on the activation or inhibition of the enzyme by a pesticide which is proportional to the concentration of the pesticide. Research on enzymatic methods of detection, as well as some of the problems and challenges associated with these methods, is extensively discussed in this review. These methods can serve as a tool for screening large samples which can be followed up with the more traditional chromatographic methods of analysis.     

Intestinal absorption of the acetamiprid neonicotinoid by Caco-2 cells: Transepithelial transport,cellular uptake and efflux

The human intestinal absorption of acetamiprid (AAP) using the Caco-2 cell line reveals that AAP flux was active in a bidirectional mode with an apparent permeability coefficient of 26^.10^?6 cm·s^?1 at 37°C. Apical uptake was concentration-dependent and unsaturated for AAP concentrations up to 200 μ M. AAP cell preloading demonstrated the involvement of active transport mechanisms. Arrhenius plot analysis revealed an unusual profile with two apparent activation energies suggesting two transport processes. Uptake Vi studies indicated the involvement of a sodium-dependent transporter, the presence of a common transporter of AAP and nicotine and the involvement of Ti-sensitive ATP-dependent efflux transporters. Apical efflux investigations showed the involvement of inward active transporter(s). Whereas vincristine had no effect on intracellular accumulation, taxol and daunorubicin treatments unexpectedly led to 10% and 23% reductions respectively, suggesting that the latter shared a common inward transporter with AAP. All these results suggest full and express AAP absorption in vivo with transport involving both inward and outward, passive and active mechanisms. Thus, AAP or its metabolites could be representative of a risk for human health after its ingestion in food.