Spray atomization and deposition patterns of one newtonian and two pseudoplastic formulations after aerial application over a mature conifer forest in Newfoundland

Abstract

Spray atomization and deposition patterns of three formulations were investigated in five aerial spray trials in Newfoundland, to understand the inter‐relationships between physical properties, drop size spectra and recovery of the spray volume at ground level. Diflubenzuron (DFB) was sprayed at 30 g active ingredient in 2.0 L/ha. Futura XLV (Fu‐XLV) and Thuricide® 48LV (Thu‐48LV), spray formulations of Bacillus thuringiensis (B.t.), were both applied undiluted at 30 BIU/ha, but in volume rates of 2.1 L/ha and 2.36 L/ha respectively. Each of the three formulations was applied over a 15 ha plot using a Piper Pawnee aircraft fitted with six Micronair® AU5000 atomizers. Spray drops were sampled with Kromekote® cards and deposits were collected on glass plates. Physical properties measured were: viscosity at variable shear rates, volatility and surface tension. The viscosities increased progressively from low (for DFB), moderate (for Thu‐48LV) to high (for Fu‐XLV) values, showing a gradual increase in pseudoplastic behaviour of the three formulations. The volatility data indicated an inverse relationship to the viscosities, but the surface tensions were similar for all the formulations.

The highly pseudoplastic Fu‐XLV atomized into the least wide drop size spectrum. The Newtonian formulation of DFB, on the other hand, atomized into the widest drop spectrum; and the moderately pseudoplastic Thu‐48LV, into an intermediate drop spectrum. Thus viscosity and volatility were more important factors in liquid atomization and drop deposition, than surface tension. Among the three meteorological factors measured, relative humidity appeared more important in drop deposition than did wind speed and temperature, within the range measured.     

Incomplete aerobic degradation of the antidiabetic drug Metformin and identification of the bacterial dead-end transformation product Guanylurea

Active pharmaceutical ingredients as well as personal care products are detected in increasing prevalence in different environmental compartments such as surface water, groundwater and soil. Still little is known about the environmental fate of these substances. The type II antidiabetic drug Metformin has already been detected in different surface waters worldwide, but concentrations were significantly lower than the corresponding predicted environmental concentration (PEC). In human and mammal metabolism so far no metabolites of Metformin have been identified, so the expected environmental concentrations should be very high.To assess the aerobic biodegradability of Metformin and the possible formation of degradation products, three Organisation of Economic Cooperation and Development (OECD) test series were performed in the present study.In the Closed Bottle test (OECD 301 D), a screening test that simulates the conditions of an environmental surface water compartment, Metformin was classified as not readily biodegradable (no biodegradation). In the Manometric Respiratory test (OEDC 301 F) working with high bacterial density, Metformin was biodegraded in one of three test bottles to 48.7% and in the toxicity control bottle to 57.5%. In the Zahn-Wellens test (OECD 302 B) using activated sludge, Metformin was biodegraded in both test vessels to an extent of 51.3% and 49.9%, respectively.Analysis of test samples by high performance liquid chromatography coupled to multiple stage mass spectrometry (HPLC-MS(n)) showed in the tests vessels were biodegradation was observed full elimination of Metformin and revealed Guanylurea (Amidinourea, Dicyandiamidine) as single and stable aerobic bacterial degradation product. In another Manometric Respiratory test Guanylurea showed no more transformation. Photodegradation of Guanylurea was also negative.A first screening in one of the greatest sewage treatment plant in southern Germany found Metformin with high concentrations (56.8 μg L⁻¹) in the influent (PEC = 79.8 μg L⁻¹), but effluent concentration was much lower (0.76 μg L⁻¹) whereas Guanylurea was detected in a low influent and high effluent concentration (1.86 μg L⁻¹). These data support the experimental findings in the OECD tests and analytical results of other studies, that Metformin under aerobic conditions can bacterially be degraded to the stable dead-end transformation product Guanylurea.     

Biological Responses to Contrasting Hydrology in Backwaters of Upper Mississippi River Navigation Pool 25

Water level management in Mississippi River Pool 25 differentially influences off-channel habitats in the mid-pool and lower pool. Hydrologic models indicate lower pool off-channel habitats dry with greater frequency and duration compared to similar habitats at mid-pool. We examined the influence of this contrasting hydrology on substrate characteristics, organic matter, macroinvertebrate, and fish communities in off-channel habitats during 2001–2003. Benthic organic matter standing stocks were stable in mid-pool habitats but lower pool values were variable because of annual differences in moist-soil vegetation production. Generally, small-bodied and multivoltine invertebrate taxa had high community biomass and dominated lower pool habitats, whereas longer-lived and large-bodied taxa were more abundant and had higher community biomass in mid-pool habitats having longer hydroperiods. Fish communities were dominated by cyprinids in both habitats, and mid-pool habitats tended to be higher in overall species richness. Unique fish taxa were collected in each pool, with primarily rheophilic forms in mid-pool habitats and limnophilic forms in lower pool habitats. Results indicate that contrasting hydrology associated with a mid-pool control point directly and indirectly influences biological communities in off-channel habitats. Further, management regimes that promote hydrologic diversity in off-channel habitats may enhance biological diversity at larger spatial and temporal scales.     

Flow cytometric measurement of the clearance rate in the blue mussel Mytilus edulis and the development of a new individual exposure system for aquatic immunotoxicological studies

Animals in poor health condition are not relevant biological models. The current study focused on the use of the clearance rate of Mytilus edulis to assess the gross physiological condition of individuals maintained in stressful experimental conditions. This approach was developed in a new, highly controlled experimental exposure device designed to investigate individual responses in aquatic ecotoxicological studies. Both clearance rate values and immune parameters analysis indicated that the health condition of mussels kept in 50ml tubes for 24h or 48h was not altered compared to controls, while most parameters were depressed after 72h. Moreover, this study confirms the relevance of flow cytometric for the measurement of clearance rate compared to techniques utilizing microscopy. Current results prompted us to perform further 24h chemical exposure using this "in tubo" device.     

Evaluation of stream ecological integrity using litter decomposition and benthic invertebrates

Biomonitoring programs to access the ecological integrity of freshwaters tend to rely exclusively on structural parameters. Here we evaluated stream ecological integrity using (a) benthic macroinvertebrate derived metrics and a biotic index as measures of structural integrity and (b) oak litter decomposition and associated fungal sporulation rates as measures of functional integrity. The study was done at four sites (S1, S2, S3 and S4) along a downstream increasing phosphorus and habitat degradation gradient in a small stream. The biotic index, invertebrate metrics, invertebrate and fungal communities' structure and sporulation rates discriminated upstream and downstream sites. Decomposition rates classified sites S4 and S2 as having a compromised ecosystem functioning. Although both functional and structural approaches gave the same results for the most impacted site (S4), they were complementary for moderately impacted sites (S2 and S3), and we therefore support the need for incorporating functional measures in evaluations of stream ecological integrity.     

Multibiomarker approach in fish to assess the impact of pollution in a large Brazilian river, Paraiba do Sul

This article examines the advantages of the use of biomarkers as environmental indicators by applying it to Paraiba do Sul watershed, one of the most important Brazilian water bodies, which is in a critical environmental situation. We use a multibiomarker approach in fish as an integrated strategy to assess the impact of pollution. It comprehends a general biomarker of fish health, the condition factor (CF), and specific biomarkers of contaminant exposure such as metallothionein (MT), acetylcholinesterase (AChE) activity and biliary polycyclic aromatic hydrocarbons (PAH) metabolites. Our results revealed different effects in the fish from diverse locations with varying degrees of pollution. Furthermore, fish located just upstream of the water-treatment plant of the metropolitan area of Rio de Janeiro has shown to be affected by metals. This study indicates the usefulness of integrating a set of biomarkers to define the effects of anthropogenic inputs in aquatic bodies under complex polluted situations.     

水环境中氨氮的分析方法进展

氮是天然水体的重要生源要素,是水体质量评价的重要指标之一。本文重点归纳总结了近年来我国在水环境中氨氮分析方法的研究进展,内容主要包括：氮的存在形态、样品预处理和氨氮的各种分析方法,指出了未来的主攻方向、重点研究领域和发展趋势。     

Phytoremediation of engineered nanoparticles using aquatic plants: Mechanisms and practical feasibility

Certain plants have demonstrated the capability to take up and accumulate metals, thus offering the potential to remediate metal-contaminated water and sediment. Several aquatic species have further been identified which can take up metal and metal oxide engineered nanoparticles (ENPs). It is important to evaluate if aquatic plants exhibiting potential for metal phytoremediation can be applied to remediation of metallic ENPs. Understanding the interactions between ENPs and aquatic plants, and evaluating possible influences on metal uptake and phytoremediation processes is therefore essential. This review article will address the feasibility of green plants for treatment of ENP-affected aquatic ecosystems. Discussion will include common types of ENPs in current use; transformations of ENPs in aquatic systems; the importance of microorganisms in supporting plant growth; ENP entry into the plant; the influence of microorganisms in promoting plant uptake; and recent findings in phytoremediation of ENP-affected water, including applications to constructed wetlands.     

Application of land-use data and screening tests for evaluating pesticide runoff toxicity in surface waters

Survey information on pesticide usage in New Zealand during 1985–1989 is summarized by regions and principal applications. Two screening tests, one based on a simple water-balance method and the other based on a semiempirical runoff formula, have been used to identify 18 pesticides with application rates that may yield runoff concentrations that are harmful to aquatic fauna. These are predominantly associated either with intensive applications in horticulture or extensive applications to cereal crops and pasture. The purpose of the screening tests was to calculate typical edge-of-field concentrations in runoff and, by comparing them with known aquatic toxicity values, determine which compounds are applied at rates that may yield toxic runoff. While it may be possible to extend these methods to calculate typical surface water concentrations, further studies will be needed to evaluate pesticide persistence and assimilation in stream channels.     

A Risk-Based Predictive Tool to Prevent Accidental Introductions of Nonindigenous Marine Species

Preventing the introduction of nonindigenous species (NIS) is the most efficient way to avoid the costs and impacts of biological invasions. The transport of fouling species on ship hulls is an important vector for the introduction of marine NIS. We use quantitative risk screening techniques to develop a predictive tool of the abundance and variety of organisms being transported by ocean-going yachts. We developed and calibrated an ordinal rank scale of the abundance of fouling assemblages on the hulls of international yacht hulls arriving in New Zealand. Fouling ranks were allocated to 783 international yachts that arrived in New Zealand between 2002 and 2004. Classification tree analysis was used to identify relationships between the fouling ranks and predictor variables that described the maintenance and travel history of the yachts. The fouling ranks provided reliable indications of the actual abundance and variety of fouling assemblages on the yachts and identified most (60%) yachts that had fouling on their hulls. However, classification tree models explained comparatively little of the variation in the distribution of fouling ranks (22.1%), had high misclassification rates (∼43%), and low predictive power. In agreement with other studies, the best model selected the age of the toxic antifouling paint on yacht hulls as the principal risk factor for hull fouling. Our study shows that the transport probability of fouling organisms is the result of a complex suite of interacting factors and that large sample sizes will be needed for calibration of robust risk models.