Fertiliser management effects on dissolved inorganic nitrogen in runoff from Australian sugarcane farms

Dissolved inorganic nitrogen (DIN) movement from Australian sugarcane farms is believed to be a major cause of crown-of-thorns starfish outbreaks which have reduced the Great Barrier Reef coral cover by ~21% (1985–2012). We develop a daily model of DIN concentration in runoff based on >200 field monitored runoff events. Runoff DIN concentrations were related to nitrogen fertiliser application rates and decreased after application with time and cumulative rainfall. Runoff after liquid fertiliser applications had higher initial DIN concentrations, though these concentrations diminished more rapidly in comparison to granular fertiliser applications. The model was validated using an independent field dataset and provided reasonable estimates of runoff DIN concentrations based on a number of modelling efficiency score results. The runoff DIN concentration model was combined with a water balance cropping model to investigate temporal aspects of sugarcane fertiliser management. Nitrogen fertiliser application in December (start of wet season) had the highest risk of DIN movement, and this was further exacerbated in years with a climate forecast for ‘wet’ seasonal conditions. The potential utility of a climate forecasting system to predict forthcoming wet months and hence DIN loss risk is demonstrated. Earlier fertiliser application or reducing fertiliser application rates in seasons with a wet climate forecast may markedly reduce runoff DIN loads; however, it is recommended that these findings be tested at a broader scale.     

The Costs of Corrosion: A Perspective

Until recently the materials engineer relied upon a combination of his experience and the use of economic analysis to make the proper choice of materials. His economic analyses required projection of useful life, probable obsolescence, eventual cost of equipment replacement—all seasoned with future predictions on the costs of money and labor.     

A Maximum Entropy Approach to Estimating Emissions

ABSTRACT

A maximum information entropy method of calculating probabilistic estimates of volatile organic compound (VOC) emissions by the wood furniture and fixture coating industry is presented. The maximum entropy approach is used to produce minimally biased probability distributions for number of firms, coating use, and coating emission factors from existing summary statistics. These distributions are combined to estimate VOC emissions. The maximum entropy emissions estimate provides information to support probabilistic modeling of regional air quality, probabilistic assessment of emission reduction strategies, and risk assessments. Accurate estimation of emission distributions produces more informed regulatory decisionmaking, risk comparisons, and regulatory and scientific priority setting.     

Effects of Sulfur Dioxide and Nitric Oxide on Mercury Oxidation and Reduction under Homogeneous Conditions

Abstract

This paper is particularly related to elemental mercury (Hg⁰) oxidation and divalent mercury (Hg²⁺) reduction under simulated flue gas conditions in the presence of nitric oxide (NO) and sulfur dioxide (SO₂). As a powerful oxidant and chlorinating reagent, Cl₂ has the potential for Hg oxidation. However, the detailed mechanism for the interactions, especially among chlorine (Cl)-containing species, SO₂, NO, as well as H₂O, remains ambiguous. Research described in this paper therefore focused on the impacts of SO₂ and NO on Hg⁰ oxidation and Hg²⁺ reduction with the intent of unraveling unrecognized interactions among Cl species, SO₂, and NO most importantly in the presence of H₂O. The experimental results demonstrated that SO₂ and NO had pronounced inhibitory effects on Hg⁰ oxidation at high temperatures when H₂O was also present in the gas blend. Such a demonstration was further confirmed by the reduction of Hg²⁺ back into its elemental form. Data revealed that SO₂ and NO were capable of promoting homogeneous reduction of Hg²⁺ to Hg⁰ with H₂O being present. However, the above inhibition or promotion disappeared under homogeneous conditions when H₂O was removed from the gas blend.     

Determination of chlorinated paraffins in sediments from the Firth of Clyde by gas chromatography with electron capture negative ionisation mass spectrometry and carbon skeleton analysis by gas chromatography with flame ionisation detection

Short chain chlorinated paraffins (SCCPs) are a group of persistent organic pollutants (POPs) of increasing concern, but are to date not widely investigated in the environment, largely due to the challenges involved in their quantification. Here, SCCPs were quantified in marine sediments from the Firth of Clyde, Scotland, by gas chromatography with electron capture negative ionisation mass spectrometry (GC-ECNIMS) and through carbon skeleton analysis by gas chromatography with flame ionisation detection (GC-FID), and the analytical challenges encountered are discussed. Concentrations in the sediments ranged from 0.4 to 69 μg kg⁻¹ when determined by GC-ECNIMS, and from 5.6 to 379 μg kg⁻¹ when determined by GC-FID. For 8 out of 11 samples, analysis by GC-FID gave higher results than analysis by GC-ECNIMS. Unexpected aspects of the analysis, such as the presence of high concentrations of longer chain chlorinated paraffins in the samples, are also presented.     

Mapping aerial metal deposition in metropolitan areas from tree bark: a case study in Sheffield, England

We investigated the use of metals accumulated on tree bark for mapping their deposition across metropolitan Sheffield by sampling 642 trees of three common species. Mean concentrations of metals were generally an order of magnitude greater than in samples from a remote uncontaminated site. We found trivially small differences among tree species with respect to metal concentrations on bark, and in subsequent statistical analyses did not discriminate between them. We mapped the concentrations of As, Cd and Ni by lognormal universal kriging using parameters estimated by residual maximum likelihood (REML). The concentrations of Ni and Cd were greatest close to a large steel works, their probable source, and declined markedly within 500 m of it and from there more gradually over several kilometres. Arsenic was much more evenly distributed, probably as a result of locally mined coal burned in domestic fires for many years. Tree bark seems to integrate airborne pollution over time, and our findings show that sampling and analysing it are cost-effective means of mapping and identifying sources.     

Managing Watershed Externalities in India: Theory and Practice

Watershed development is the focus of poverty alleviation programs in rural India. Watershed projects aim to solve problems of externalities, but they also create their own externalities, which cause uneven distribution of costs and benefits that undermine project objectives and harm the poor. Numerous approaches exist to internalize externalities, including awareness creation, moral suasion, investment subsidies, regulatory limits and fines, indirect benefits, mergers, and recent innovations like payment for environmental services and cap and trade. These can be judged on several criteria; the best approach would solve the problem cost effectively and help or at least not hurt poor people. Watershed projects in India were examined to identify the approaches taken to internalize watershed externalities. Investment subsidies and indirect employment benefits are the least effective approaches theoretically, but they are the most commonly applied, most likely because they are easy to administer and bring popular short term gains. Some theoretically favorable approaches that have been used elsewhere, such as payment for environmental services, may not work as well in India due to high transaction costs. However, one key innovation that easily could be applied in India is to make investment subsidies contingent on performance. Legal support and property rights reform would be needed for other favorable approaches.