bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ecotoxicology and pesticides in tropical aquatic ecosystems of Central America
Authors: Castillo Luisa E , de la Cruz Elba , Ruepert Clemens 
Published: March 2010

AbstractAlthough pesticide use is high in the Central American region, few studies concerning environmental levels and effects of pesticides in aquatic ecosystems have been conducted. In this review 18 studies were identified, most of which deal exclusively with organochlorine residues, but other chemical groups also were studied and found in tropical aquatic ecosystems. Only five studies considered effects of pesticides on aquatic organisms; four of these examined both the presence of pesticides in environmental substrates and field effects. Major research needs include studies on fate and degradation in tropical conditions; acute and chronic toxicity to native species; effects of temperature, humidity, and other characteristics of tropical conditions on toxicity, as well as effects of pesticides on tropical ecosystems.
Sediment contamination problems in the Caribbean islands: Research and regulation
Authors: Ross Philippe , DeLorenzo Marie E 
Published: March 2010

Abstract
Sediment contamination in the Caribbean has not been extensively studied. This review article outlines known cases of sediment contamination in the Caribbean and their impacts on Caribbean ecosystems. It also discusses regulation and remediation of contaminated sediments in the Caribbean and speculates on what the future holds regarding sediment toxicity. Existing information suggests that sediment contamination may be widespread, although not severe in most areas. Puerto Rico and the U.S. Virgin Islands contain two National Priority List sites and one candidate site under U.S. Superfund jurisdiction. These territories will be more extensively studied under the U.S. Environmental Monitoring and Assessment Program. Regulation of sediment contamination is difficult within the Caribbean region because jurisdiction is shared by 27 independent countries and a number of territories and dependencies. In addition to establishing control of natural resources within a 200–mile offshore limit for each Caribbean nation, the recently created Exclusive Economic Zone contains provisions for environmental protection and management, but many governments in the region lack the resources to implement them. The Caribbean Action Plan formalizes international cooperation and assistance to overcome some of these limitations. Many Caribbean countries have experienced a strong industrial expansion and a rapid population growth during the last 30 to 40 years, and there is potential for further contamination as these islands develop.
Ecotoxicology of pesticides in the tropical paddy field ecosystem
Authors: Abdullah Abdul R , Bajet Cristina M , Matin Malek A , Nhan Duc D , Sulaiman Abdul H 
Published: March 2010

Abstract
In tropical countries rice has been identified as one of the crops that is particularly susceptible to the negative impacts of pesticide use. In addition to the physicochemical nature of the pesticide, tropical climatic conditions and agricultural practices play important roles in determining the fate and distribution of pesticides in the tropical paddy field ecosystem. The assessment of ecotoxicological effects of pesticides in the tropical paddy field ecosystem has been based primarily on acute lethality tests conducted on fish species commonly found in paddy fields. The effects of pesticides in the paddy field ecosystem on other nontarget organisms ranging from microalgae and cyanobacteria to paddy field crabs have also been investigated, although such studies are limited. As a means to promote a more judicious use of pesticides in the paddy field, the adoption of integrated pest management strategies have resulted in varying degrees of success. The most widely accepted form of control measure is the integration of multiresistant cultivars with reduced use of pesticides. Effective training of the paddy farmer has been identified as the key to successful implementation of integrated pest management strategies.
Fish and wildlife resources in the pantanal wetlands of Brazil and potential disturbances from the release of environmental contaminants
Authors: Alho Cleber J R , Vieira Luiz M 
Published: March 2010

Abstract
The Pantanal is one of the world's largest wetland ecosystems, encompassing 140,000 km2. The region is a breeding ground for waterfowl, and enormous rookeries of storks, herons, egrets, and ibises indicate a vast abundance of birds. The Pantanal is also one of the most important refuges for many of Brazil's threatened or endangered species, such as jaguars, giant anteaters, and swamp deer. The productive web of waters supports an important fishery industry. The Pantanal, with its extraordinary diversity and abundance of wildlife, is a threatened region. Deforestation, expanding agriculture, illegal hunting and fishing, unplanned tourism, and pollution with pesticides have caused a progressive deterioration of the natural environment, placing one of Brazil's most important ecosystems at risk. Gold mining is still common in the northern Pantanal. Along the Cuiabá river are 700 functional gold-mining dredges. In the town of Poconé, unregulated gold mines have also contaminated the area with mercury, which is used during the processing of gold. Approximately 50% of the fishes from the Cuiabá River and 35% from the Bento Gomes River have mercury levels higher than 0.5 μg/g, which is beyond the international standard for contamination. Fishes from the Paraguay River have levels below 0.5. Birds like Phalacrocorax olivaceus, Aramus guarauna, and Rosthramus sociabilis were also contaminated. No research has been conducted on the fate of pesticides in the Pantanal. However, because of the huge demand for soybean plantations on the upland areas surrounding Pantanal, the application of toxic agricultural chemicals is very common.
Deficiencies and toxicities of trace elements and micronutrients in tropical soils: Limitations of knowledge and future research needs
Authors: Davies Brian E 
Published: March 2010

Abstract
This article reviews present knowledge concerning deficiencies and toxicities of trace elements and micronutrients in tropical soils. The myth that all tropical soils are highly leached and nutrient-poor is challenged. Continuing use of the term “laterite” by ecologists and geologists is criticized and adoption of “plinthite” is urged. The trace element content of plinthite and its possible influence on micronutrient availability are described. Micronutrient limitations of tropical agriculture are related to soil type and formation, and the special problem of aluminum toxicity in acid soils is discussed in both agricultural and ecological contexts. Studies of micronutrient cycling in tropical forests or savannas are needed to supplement the emerging picture of the complexities of major element cycles in these ecosystems. Interest in gold mining has stimulated studies of the element in tropical soils, and mining of the metal is leading to mercury pollution in Amazonia.
Degradation of pesticides applied to banana farm soil: Comparison of indigenous bacteria and a microbial mat
Authors: Murray Reynold , Phillips Peter , Bender Judith 
Published: March 2010

Abstract
Indigenous bacteria from St. Vincent (West Indies) banana farm soil, enriched cultures of three isolates, and a microbial mat were tested for their ability to degrade carbofuran, chlordane, paraquat, and prophos. In single-pesticide application experiments, only 35.0% of the parent carbofuran was recovered after 21 d; paraquat recovery was 40.0%, and chlordane, 91.0%. In a mixture containing each pesticide, 42.0% of the parent carbofuran was recovered, and paraquat and chlordane recoveries were 52.0% and 94.0%, respectively. A microbial mat and the isolates were shown to mineralize [14C]carbofuran. Best results (93.11 μg [14C]carbofuran/kg dry microbial mat) were from a 15-d dark soil experiment. In field trials, the concentration of carbofuran decreased 82% with microbial mat treatment, and control plot concentrations actually increased 26%, The concentration of prophos decreased significantly after 4 d (0–6 mg/kg) in the plots with a microbial mat, whereas in control plots it increased from 7 to 12 mg/kg at day 0 to 180 mg/kg at day 4. After 60 d prophos was not detected in any microbial mat plot, whereas all but one control plot had it (0–12 mg/kg) in the soil.
Tropical ecotoxicology: Status and needs
Authors: Lacher Thomas E , Goldstein Michael I 
Published: March 2010

AbstractEcotoxicology has focused almost exclusively on countries and ecosystems in temperate zones. Tropical ecosystems, which combined contain as much as 75% of the global biodiversity, have been neglected. Tropical ecosystems are under increasing threat of development and habitat degradation from population growth and urbanization, agricultural expansion, deforestation, and mining. Some of these activities also lead to the release of toxic substances into the environment. Little research in ecotoxicology has been carried out in tropical environments. Techniques and procedures developed for temperate environments are often applied, even though physical and chemical environmental parameters in the tropics can be very different. Most research has focused on water quality and aquatic toxicology. The regulatory environment also varies among countries. We present a review of the literature on tropical ecotoxicology, with an emphasis on Latin America and the Caribbean. We also address priority areas for immediate research in the tropics. These include large-scale agricultural activities, especially banana, pineapple, and soybean farming, and gold mining with the associated heavy use of mercury. We outline the special issues that must be addressed as the field of tropical ecotoxicology progresses.
Extrapolating mineralization rates from the ready Co2 screening test to activated sludge, river water, and soil
Authors: Federle Thomas W , Gasior Sally D , Nuck Barbara A 
Published: March 2010

Abstract
The objective of this research was to derive empirical extrapolation factors by concurrently measuring mineralization rates of nine diverse chemicals in a Ready CO2 test (modified Sturm) and realistic 14C tests using activated sludge, river water, and sludge-amended soil while holding other variables constant. All nine chemicals were mineralized in the Ready test and each of the compartments, but no significant statistical relationships existed between biodegradation rates in the various tests. Mineralization rates in the Ready test were on average 8.1, 2.5, and 1.2 times lower than the rates in realistic activated sludge, river water, and soil tests, but variability in the scaling factors spanned up to 1.5 orders of magnitude. The scaling factors for extrapolating from ready CO2 data ranged from 1.7 to 19 for activated sludge, from 0.1 to 5.6 for river water, and from 0.3 to 2.8 for soil. Correlation analysis revealed that the scaling factors from the CO2 test to activated sludge and river water were related to the quantitative structure-activity relationship based solubility and log Kow estimates for the test chemicals.
Influence of pH on the toxic effects of zinc, cadmium, and pentachlorophenol on pure cultures of soil microorganisms
Authors: van Beelen Patrick , Fleuren-Kemilä Arja K 
Published: March 2010

Abstract
In this study the effect of the acidification of soil pore water on the uptake and toxicity of cationic and anionic pollutants was measured in an experimental model system. The influence of pH on the toxic effects of zinc, cadmium, and pentachlorophenol was studied in buffered suspensions of pure cultures of soil microorganisms. In this system the speciation of the toxicant, the pH, and the biomass are defined, constant, and thus easier to study than in a system with the solid soil matrix and pore water. The mineralization of [14C]acetate to 14CO2 was used to measure the toxic effects of pollutants on a fungus (Aspergillus niger CBS 121.49), an actinomycete (Streptomyces lividans 66), two Gram-negative Pseudomonas putida strains (MT-2 and DSM 50026), and a Gram-positive strain (Rhodococcus erythropolis A177). Large differences in sensitivity were observed between the species. For pentachlorophenol the highest EC50 was 81 mg/L for Pseudomonas putida at pH 8, whereas the lowest was 0.13 mg/L for Aspergillus niger at pH 6. Aspergillus niger was not sensitive to 1,000 mg Zn/L, whereas Pseudomonas putida at pH 7.8 showed the lowest EC50, 0.14 mg Zn/L. When pH was increased, pentachlorophenol became less toxic and showed less sorption to the biomass, whereas zinc and cadmium became more toxic and showed more sorption to the biomass. The results indicate that higher pore-water concentrations due to acidification of zinc- and cadmium-polluted soils may not be accompanied by increased toxic effects on microorganisms because of the relatively low toxicity of these metals in pore water at low pH.
Measurements of pesticide spray drift deposition into field boundaries and hedgerows: 1. Summer applications
Authors: Longley Martin , Čilgi Tamer , Jepson Paul C , Sotherton Nicolas W 
Published: March 2010

Abstract
The drift of fluorescent tracer in water and formulated pesticide sprays was measured at different heights and distances within 6-m-wide buffer strips (“Conservation Headlands”) and field boundaries surrounding mature winter cereal fields. Spray deposits were taken from artificial collectors. There was a diminution in deposition at the hedgerow, where a 6-m-wide buffer strip of unsprayed crop was employed between the sprayer and the hedgerow compared to where the entire crop edge was fully sprayed. There was some evidence that a mature crop would absorb some of this spray drift, reducing deposition on the hedge flora below crop level and, therefore, the nature of the buffer strip as well as it's width were thought to be important in determining hedgerow deposition rates. Frequency distributions of deposition along strips of hedgerow revealed that the unsprayed buffer zone also served to reduce the peaks in drift that might occur as a result of the pitch and yaw of travelling tractor booms. The vegetational complexity of the hedge bottom was also shown to determine spray deposition within field boundaries. Larvae of the cabbage white butterfly (Pieris brassicae[L.]) showed higher mortalities when exposed to hedgerow grasses adjacent to conventionally sprayed headlands compared to those adjacent to a Conservation Headland. A simple methodology for spray deposition studies is outlined, and implications of pesticide drift into field boundaries discussed.
Organic pollutants in the coastal marine environment off San Diego, California. 3. Using linear alkylbenzenes to trace sewage-derived organic materials
Authors: Zeng Eddy Y , Khan Azra R , Tran Kim 
Published: March 2010

Abstract
Linear alkylbenzenes (LABs) were detected in the Point Loma Wastewater Treatment Plant (PLWTP) effluent, Tijuana River runoff, microlayer, water column particulates, and sediments collected off the coast of San Diego in 1994. The distributions of LABs in various media and sampling locations suggested that these compounds were essentially derived from domestic waste discharges. The PLWTP outfall is a major source for LAB inputs, while the Tijuana River runoff discharges much lower amounts of LABs. However, the contents of sewage-derived organics can be enhanced in the sea surface microlayer near the mouth of the Tijuana River. In addition, the I/E ratios indicated that 30-55% of the LABs were degraded in the water column particulates and sediments. Other processes (e.g., dilution, evaporation, bioaccumulation, etc.) may also be important in removing LABs from the discharge zone. Sewage-derived organic materials can be carried into remote areas via suspension of fine particulates.
Effects of cations, temperature, and creosote on degradation of indole by Desulfobacterium indolicum (DSM 3383)
Authors: Licht Dorthe , Arvin Erik , Ahring Birgitte K 
Published: March 2010

Abstract
This work describes the activity of Desulfobacterium indolicum under different conditions. Hydroxylation of indole by the sulfate-reducing marine bacterium D. indolicum was related to the concentration of Na+ and Mg2+, whereas K+ and Ca2+ had no influence. Hydroxylation of indole by D. indolicum was possible in normal medium with cation concentrations corresponding to seawater at low temperatures (10-26°C). The effect of reduced cation concentrations was most pronounced at high temperatures (29 and 36°C) where only an incomplete hydroxylation was observed in the medium with reduced cation concentrations. Desul-fobacterium indolicum was more sensitive to the presence of an artificial creosote mixture when depleted for cations. Sixty milligrams of artificial creosote per liter inhibited hydroxylation of indole by 30% in a normal growth medium compared to an 86% inhibition in a medium with low concentrations of cations. Indole and quinoline were the only compounds degraded from a creosote mixture consisting of 25 compounds. It was concluded that D. indolicum is active towards indole and quinoline under growth conditions quite distinct from its optimal laboratory conditions.
Effect of copper chloride in vitro and in vivo on the hepatic erod activity in the fishDicentrarchus labrax
Authors: Stien Xavier , Risso Christine , Gnassia-Barelli Mauricette , Roméo Michèle , Lafaurie Marc 
Published: March 2010

AbstractThe effect of copper chloride was studied on the hepatic microsomal 7-ethoxyresorufin-O-deethylase (EROD) activity of the fish Dicentrarchus labrax intraperitoneally injected with benzo[a]pyrene (BaP). In vitro experiments showed that copper significantly decreased EROD activity, and IC50 was estimated at 50 μg Cu/L. The apparent Michaelis constant (Km) of cytochrome P4501A was constant, whereas maximum velocity (Vmax) decreased as a function of copper added to the incubation medium. (Km) of nicotinamide adenine dinucleotide phosphate [NADPH]-cytochrome P450 reductase increased as a function of copper concentration, whereas Vmax remained constant. Absorption spectra showed that the amount of cytochrome P420s increased as a function of copper concentrations added to the medium at the expense of cytochrome P450s. The injection of copper and BaP (in vivo experiments) to fish decreased EROD activity compared with the injection of BaP alone. An increase of immunoquantified CYP1A content measured by Western blotting (intense band of 55–60 kDa molecular weight) was noted in microsomes of fish injected with BaP compared with controls. In the case of fish treated with copper and BaP, the band was less intense and accompanied by another band of lower molecular weight. The destruction of the native P450s spectrophotometrically measured in the presence of copper implied that the catalytic activity would be diminished. This was confirmed by decreased EROD activity after either in vitro additions or in vivo treatment with copper. Moreover, immunodetection experiments suggested that the decrease of the catalytic activity resulted more from cytochrome P450s loss than from direct inhibition of EROD activity by copper.
Effects of free Cu2+ and Zn2+ ions on growth and metal accumulation in freshwater algae
Authors: Knauer Katja , Behra Renata , Sigg Laura 
Published: March 2010

Abstract
Five species of unicellular green algae were exposed to a broad range of Cu2+ and Zn2+ concentrations to examine the relationship between the free Cu2+ and Zn2+ ion concentrations and algal growth at metal concentrations relevant for freshwater phytoplankton. We estimated extra- and intracellular metal concentrations and characterized the adsorption of copper and zinc on algal surfaces. The optimal growth rate of Scenedesmus subspicatus occurred in a broad range of Cu2+ and Zn2+ concentrations (from 10−15 to 10−7 and from 10−12 to 10−55 M, respectively). Chlamydomonas reinhardtii reacted more sensitively toward copper, optimal growth was achieved only at a pCu (= -log[Cu2+]) around 11, whereas growth was optimal over a broad range of free Zn2+ concentrations (from 10−12 to 10−6 M). The optimal range for growth of Chlorella fusca occurred over about three orders of magnitude of the free Cu2+ concentration (from 10−13 to 10−10 M). Chlamydomonas cultures isolated from Lake Constance tolerated Cu2+ concentrations over seven orders of magnitude (pCu = 7 to 14). The growth of algae showed a high tolerance toward high intracellular copper and zinc concentrations. This suggests that the cells may immobilize the metals intracellularly. The affinity of copper for algal surfaces is higher than that of zinc in the experimental concentration range: adsorption constants log KCu (11.06) &gt; log KZn (6.49) (pH = 7.9). These freshwater algae tolerate higher Cu2+ and Zn2+ concentrations than marine algal species. In comparison to our lake data, the results obtained from the culture algae indicate a possible role for copper as a limiting factor for certain algal species in eutrophic lakes.
Interactive effects on the erod-inducing potency of polyhalogenated aromatic hydrocarbons in the chicken embryo hepatocyte assay
Authors: Verhallen Eeske Y , van den Berg Martin , Bosveld A T C 
Published: March 2010

Abstract
The chicken embryo hepatocyte-7-ethoxyresorufin O-deethylase (EROD) assay is used as a method to measure the amount of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) equivalents (TEQs) in environmental samples. A common feature of EROD-induction assays in vertebrates is that they generate biphasic dose-response relationships that show dose-related increases of the EROD induction to a maximum activity, followed by a dose-related decrease at higher concentrations. In general, the maximum achievable enzyme activity decreases with increasing median effective concentration (EC50). This suggests that aryl hydrocarbon (Ah)-receptor binding affinity is not the only factor determining the enzyme activity. An additional factor can obscure the maximum EROD activity (Ymax) and EC50 of the enzyme activity. Cytotoxicity and competitive inhibition are ruled out as possible influencing factors. Coadministration of 2, 2′, 4, 4′, 5, 5′-hexachlorobiphenyl (PCB 153) and 2, 3, 7, 8-TCDD significantly reduces the EC50 value compared to administration of TCDD alone. The dose-related decrease at higher concentrations has been suggested to be induced by mechanisms other than the Ah-receptor-related mechanism responsible for the observed increases at low concentrations. These interactive effects have serious consequences for risk assessment based on bioassay-derived TEQs.