The Environmental Protection Agency (EPA) provides access to information on a variety of topics related to the environment and strives to inform citizens of health risks. The EPA also has an extensive library network that consists of 26 libraries throughout the United States, which provide access to a plethora of information to EPA employees, scientists, and researchers. The EPA implemented a reorganization project to digitize their materials so they would be more accessible to a wider range of users, but this plan was drastically accelerated when the EPA was threatened with a budget cut. It chose to close and reduce the hours and services of some of their libraries. As a result, the agency was accused of denying users the “right to know” by making information unavailable, not providing an adequate strategic plan, and discarding vital materials. This case study explores the background of the digitization project, the practices implemented, and the critiques of the project.

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The Environmental Protection Agency

Phosphorus is the second important key element after nitrogen as a mineral nutrient in terms of quantitative plant requirement. Although abundant in soils, in both organic and inorganic forms, its availability is restricted as it occurs mostly in insoluble forms. The P content in average soil is about 0.05% (w/w) but only 0.1% of the total P is available to plant because of poor solubility and its fixation in soil (Illmer and Schinner, Soil Biol Biochem 27:257-263, 1995). An adequate supply of phosphorus during early phases of plant development is important for laying down the primordia of plant reproductive parts. It plays significant role in increasing root ramification and strength thereby imparting vitality and disease resistance capacity to plant. It also helps in seed formation and in early maturation of crops like cereals and legumes. Poor availability or deficiency of phosphorus (P) markedly reduces plant size and growth. Phosphorus accounts about 0.2 - 0.8% of the plant dry weight. To satisfy crop nutritional requirements, P is usually added to soil as chemical P fertilizer, however synthesis of chemical P fertilizer is highly energy intensive processes, and has long term impacts on the environment in terms of eutrophication, soil fertilility depletion, carbon footprint. Moreover, plants can use only a small amount of this P since 75–90% of added P is precipitated by metal–cation complexes, and rapidly becomes fixed in soils. Such environmental concerns have led to the search for sustainable way of P nutrition of crops. In this regards phosphate-solubilizing microorganisms (PSM) have been seen as best eco-friendly means for P nutrition of crop. Although, several bacterial (pseudomonads and bacilli) and fungal strains (Aspergilli and Penicillium) have been identified as PSM their performance under in situ conditions is not reliable and therefore needs to be improved by using either genetically modified strains or co-inoculation techniques. This review focuses on the diversity of PSM, mechanism of P solubilization, role of various phosphatases, impact of various factors on P solubilization, the present and future scenario of their use and potential for application of this knowledge in managing a sustainable environmental system.

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Phosphate solubilizing microbes: sustainable approach for managing phosphorus deficiency in agricultural soils

Organotin compounds are ubiquitous contaminants in the environment. The high biological activity of some compounds toward aquatic organisms lead to deleterious impacts in aquatic ecosystems. Here, the aquatic ecotoxicology of organotins is reviewed based on a multidisciplinary approach involving environmental chemical, toxicological, and ecological aspects. Basic results were obtained both with field and laboratory studies, and some of the most important recent results and conclusions are critically reviewed. The contamination of and fate in aquatic systems is reported and linked with effects at different levels of biological organization. Major emphasis is placed on the development of a concept of ecotoxicology that encompasses not only effect assessment alone, but also integrates environmental chemistry with aquatic toxicology. Thereby, the influence of speciation for bioavailability, basic modes of toxic action, and aquatic toxicity are discussed. This case study on organotins allows to a certain extent generalizations to ecotoxicology in general.

Ecotoxicology of organotin compounds.

Organotin compounds in the environment — an overview

Compared with the other major nutrients, phosphorus is by far the least mobile and available to plants in most soil conditions. Although phosphorus is abundant in soils in both organic and inorganic forms, it is frequently a major or even the prime limiting factor for plant growth. The bioavailability of soil inorganic phosphorus in the rhizosphere varies considerably with plant species, nutritional status of soil and ambient soil conditions. To circumvent phosphorus deficiency, phosphate-solubilizing microorganisms (PSM) could play an important role in supplying phosphate to plants in a more environmentally-friendly and sustainable manner. The solubilization of phosphatic compounds by naturally abundant PSM is very common under in vitro conditions; the performance of PSM in situ has been contradictory. The variability in the performance has thus greatly hampered the large-scale application of PSM in sustainable agriculture. Numerous reasons have been suggested for this, but none of them have been conclusively investigated. Despite the variations in their performance, PSM are widely applied in agronomic practices in order to increase the productivity of crops while maintaining the health of soils. This review presents the results of studies on the utilization of PSM for direct application in agriculture under a wide range of agro-ecological conditions with a view to fostering sustainable agricultural intensification in developing countries of the tropics and subtropics.

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Role of phosphate-solubilizing microorganisms in sustainable agriculture — A review

An ultratrace method for the analysis of aquatic anthropogenic butyltin and mixed methylbutyltin species using simultaneous hydridization with sodium borohydride and extraction into dichloromethane is described The detection limits for a 100-mL sample are 7 ng of Sn/L for tetrabutyltin, 7 ng of Sn/L for tributyltin, 3 ng of Sn/L for dibutyltin, and 22 ng of Sn/L for monobutyltin Detection limits of approximately 1-2 ng of Sn/L for tri- and tetrabutyltin and less than 1 ng of Sn/L for dibutyltin species were achieved with 800-mL samples The presence of tetrabutyltin in harbor waters is reported 39 references, 9 figures, 2 tables

Comprehensive method for determination of aquatic butyltin and butylmethyltin species at ultratrace levels using simultaneous hydridization extraction with gas chromatography-flame photometric detection.

Application of a Liquid Chromatograph Coupled with a Flameless Atomic Absorption Detector for Speciation of Trace Organometallic Compounds

: A method was developed permitting detection and speciation of both volatile and non-volatile organotin compounds in aqueous media. The method employed a commercial gas chromatograph (GC) with a flame photometric detector (FPD) optimized for tin-selective detection. Solvated organotins were volatilized with sodium borohydride during the purge cycle of a commercial automatic purge and trap sampler (P/T). Purged volatiles and species volatilized by hydridization were concentrated on a Tenax-GC filled trap at ambient temperature. Tetramethyltin (Me4SN) present in the sample is unaffected by the reduction process. The P/T-GC-FPD method was used to analyze water samples collected from the Chesapeake Bay and Baltimore Harbor. Varying amounts of methyltin compounds, including tetramethyltin and methyltin hydrides, were detected in polluted sites in Baltimore Harbor. In vitro studies using GC-MS confirmed earlier reports of microbial methylation of inorganic Sn(IV) by a strain of Pseudomonas species isolated from the Chesapeake Bay. Consequently, biogenic origins are suspected for the methylstannanes (Me(n)SnH(4-n) n = 2,3) found in the Chesapeake Bay. (Author)

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Gas-chromatographic speciation of methylstannanes in the Chesapeake Bay using purge and trap sampling with a tin-selective detector

The LC50 concentrations of a series of 15 structurally distinct diorganotins (R2SnX2) and triorganotins (R3SnX) were determined for zoeae of the mud crab Rhithropanopeus harrisii. Zoeae were exposed from hatching until metamorphosis, at ˜14 d. The LC50 values varied by almost 4 orders of magnitude, from the least toxic aquated species, dimethyltin (LC50 = 92,276 nM) to the most toxic, tricyclohexyltin (LC50 = 19.8 nM). Within a homologous series, the diorganotin was less toxic than the corresponding triorganotin, but the toxicity of the two classes overlapped, e.g., dicyclohexyltin was more toxic than trimethyltin and about as toxic as triethyltin. Correlations between the Hansch π parameter and the LC50, and between total surface area and the LC50, suggest that aqueous thermodynamic activity (hydrophobicity), a function of the organic ligand attached to tin, controls bioconcentration and thus the lethal dose. This conclusion is substantiated by the observation of a single linear relationship between a sum of Hansch fragment constants and the LC50 values for both the di- and triorganotins. The difference in toxicity between di- and trialkyltins results from a decrease in hydrophobic character when a hydroxyl group is substituted for an organic ligand in the former. Any electronic effect of the organic ligand is overwhelmed by the factors that control hydrophobic behavior, as evidenced by the observed poor correlations with χ.

Structure-activity relationships for organotin compounds

: Based on their behavior as stable cations in saline solutions, direct trace speciation of a broad range of organotins, representing current industrial or environmental interests, was performed by combination of an tin-specific graphite furnace atomic detector with HPLC employing reverse bonded-phase strong cations exchange columns. Column and system performance and detection limits (5-30 ng as tin) vary predictably with individual substituents on organotins, but are easily optimized, for example, for identifying marine antifoulant leachates. (Author)

Frederick E. Brinckman

Papers

Comprehensive method for determination of aquatic butyltin and butylmethyltin species at ultratrace levels using simultaneous hydridization extraction with gas chromatography-flame photometric detection.

Application of a Liquid Chromatograph Coupled with a Flameless Atomic Absorption Detector for Speciation of Trace Organometallic Compounds

Gas-chromatographic speciation of methylstannanes in the Chesapeake Bay using purge and trap sampling with a tin-selective detector

Structure-activity relationships for organotin compounds

Speciation of Trace Di- and Triorganotins in Water by Ion-Exchange HPLC-GFAA