A new method to quantify the impact of soil carbon management on biophysical soil properties: the example of two apple orchard systems in New Zealand

A new method to diagnose the environmental sustainability of specific orchard management practices was derived and tested. As a significant factor for soil quality, the soil carbon (C) management in the topsoil of the tree-row of an integrated and organic apple orchard was selected and compared. Soil C management was defined as land management practices that maintain or increase soil C. We analyzed the impact of the soil C management on biological (microbial biomass C, basal respiration, dehydrogenase activity, respiratory quotient) and physical (aggregate stability, amount of plant-available water, conductive mean pore diameter near water saturation) soil properties. Soil in the alley acted as a reference for the managed soil in the tree row. The total and hot-water-extractable C amounts served as a combined proxy for the soil C management. The soil C management accounted for 0 to 81% of the degradation or enhancement of biophysical soil properties in the integrated and organic system. In the integrated system, soil C management led to a loss of C in the top 0.3 m of the tree row within 12 yr, causing a decrease in microbial activities. In the tree row of the organic orchard, C loss occurred in the top 0.1 m, and the decrease in microbial activities was small or not significant. Regarding physical soil properties, the C loss in the integrated system led to a decrease of the aggregate stability, whereas it increased in the organic system. Generally, the impact of soil C management was better correlated with soil microbial than with the physical properties. With respect to environmental soil functions that are sensitive to the decrease in microbial activity or aggregate stability, soil C management was sustainable in the organic system but not in the integrated system.     

Soil-atmosphere trace gas exchange in semiarid and arid zones

A review is presented on trace gas exchange of CH4, CO, N2O, and NOx arising from agriculture and natural sources in the world's semiarid and arid zones due to soil processes. These gases are important contributors to the radiative forcing and the chemistry of the atmosphere. Quantitative information is summarized from the available studies. Between 5 and 40% of the global soil-atmosphere exchange for these gases (CH4, CO, N2O, and NOx) may occur in semiarid and arid zones, but for each of these gases there are fewer than a dozen studies to support the individual estimates, and these are from a limited number of locations. Significant differences in the biophysical and chemical processes controlling these trace gas exchanges are identified through the comparison of semiarid and arid zones with the moist temperate or wet/dry savanna land regions. Therefore, there is a poorly quantified understanding of the contribution of these regions to the global trace gas cycles and atmospheric chemistry. More importantly, there is a poor understanding of the feedback between these exchanges, global change, and regional land use and air pollution issues. A set of research issues is presented.     

Global Urban Growth and the Geography of Water Availability,Quality, and Delivery

Globally, urban growth will add 1.5 billion people to cities by 2030, making the difficult task of urban water provisions even more challenging. In this article, we develop a conceptual framework of urban water provision as composed of three axes: water availability, water quality, and water delivery. For each axis, we calculate quantitative proxy measures for all cities with more than 50,000 residents, and then briefly discuss the strategies cities are using in response if they are deficient on one of the axes. We show that 523 million people are in cities where water availability may be an issue, 890 million people are in cities where water quality may be an issue, and 1.3 billion people are in cities where water delivery may be an issue. Tapping into groundwater is a widespread response, regardless of the management challenge, with many cities unsustainably using this resource. The strategies used by cities deficient on the water delivery axis are different than for cities deficient on the water quantity or water quality axis, as lack of financial resources pushes cities toward a different and potentially less effective set of strategies.     

Mobile passive samplers: concept for a novel mode of exposure

Integrative passive sampling with devices such as semipermeable membrane devices generally relies on rigs for month-long static exposures in water. We evaluate here whether mobile exposures of passive samplers can provide reliable estimates of dissolved contaminant concentrations. Mobile exposures were obtained by towing samplers fastened to the end of a benthic trawl net. Significant and reproducible absorption of polycyclic aromatic hydrocarbons during 5 h-long deployments was made possible by high sampling rates resulting from high water turbulences during towing at 1.2-1.5 knots. Sampling rates (72-215 L d⁻¹) estimated from the dissipation of performance reference compounds were supported by in situ calibration with samplers exposed for a 30 days in the vicinity of the test site. Higher fluoranthene and pyrene absorption in samplers exposed to the trawling-induced sediment plume could be attributed to desorption from re-suspended sediments. This mode of exposure has the potential to be used in monitoring programmes.     

A lake classification concept for a more accurate global estimate of the dissolved inorganic carbon export from terrestrial ecosystems to inland waters

The magnitude of lateral dissolved inorganic carbon (DIC) export from terrestrial ecosystems to inland waters strongly influences the estimate of the global terrestrial carbon dioxide (CO₂) sink. At present, no reliable number of this export is available, and the few studies estimating the lateral DIC export assume that all lakes on Earth function similarly. However, lakes can function along a continuum from passive carbon transporters (passive open channels) to highly active carbon transformers with efficient in-lake CO₂ production and loss. We developed and applied a conceptual model to demonstrate how the assumed function of lakes in carbon cycling can affect calculations of the global lateral DIC export from terrestrial ecosystems to inland waters. Using global data on in-lake CO₂ production by mineralization as well as CO₂ loss by emission, primary production, and carbonate precipitation in lakes, we estimated that the global lateral DIC export can lie within the range of \( {0.70}_{-0.31}^{+0.27} \) to \( {1.52}_{-0.90}^{+1.09} \) Pg C yr^?1 depending on the assumed function of lakes. Thus, the considered lake function has a large effect on the calculated lateral DIC export from terrestrial ecosystems to inland waters. We conclude that more robust estimates of CO₂ sinks and sources will require the classification of lakes into their predominant function. This functional lake classification concept becomes particularly important for the estimation of future CO₂ sinks and sources, since in-lake carbon transformation is predicted to be altered with climate change.     

A decision tree approach modelling functional group abundance in a pasture ecosystem

Decision tree, one of the data mining approaches, was used to model the relative abundance of five functional groups of plant species, namely high fertility response grasses (HFRG), low fertility tolerance grasses (LFTG), legume, moss and flatweeds in a New Zealand hill-pasture ecosystem using aboveground biomass. The model outputs were integrated with a geographic information system (GIS) to map and validate the predictions on a pasture. The decision tree models clearly revealed the interactions between the functional groups and environmental and management factors, and also indicated the relative importance of these factors in influencing the functional group abundance. Soil Olsen P was the most significant factor influencing the abundance of LFTG and moss, while soil bulk density, slope and annual P fertiliser input were the most significant factors influencing the abundance of legume, HFRG and flatweeds, respectively. Generally, slope and soil Olsen P were the two key factors underlying the patterns of abundance for these five functional groups. For the five functional groups studied, there was an overall predictive accuracy of 75%. Modelling functional group abundance simplified the investigation of the complex interrelationship between species and environment in a pasture ecosystem. The integration of the decision tree with GIS in this study provides a platform to investigate community structure and functional composition for a pasture over space, and thus can be applied as a tool in pasture management.     

Some Lessons Learned from Public Health on the Process of Adaptation

Lessons learned from more than 150 years of public health research and intervention can provide insights to guide public health professionals and institutions as they design and implement specific strategies, policies, and measures to increase resilience to climate variability and change. This paper identifies both some modifications to public health systems that may enhance adaptive capacity, and lessons drawn from the history of managing environmental and other threats in the public health sector that may have relevance for other sectors as they design approaches to increase their adaptive capacity to more effectively cope with climate variability and change. The views expressed are the author’s own and do not represent official US EPA policy.     

Relationships between water mass characteristics and estimates of fish population abundance from trawl surveys

The Canadian Department of Fisheries and Oceans conducts annual bottom trawl surveys to monitor changes in the abundance of the major commercially important groundfish populations. Some of these surveys have been in operation for almost 20 yr. The estimates from these surveys often indicate rapid changes in abundance over time beyond that expected from the population dynamics of the fish. Much of this interannual change has been interpreted as variation, the magnitude of which has often made it difficult to measure anything but the most severe effects of fishing, pollution or any other intervention on the population. Recent studies have shown that some of this variation may be attributed to changes in catchability of fish due to the effects of environmental variables on fish distribution. Annual changes in abundance as estimated from such field surveys may be confounded by changes in catchability due to annual changes in environmental conditions. In this study, trawl catches of age 4 Atlantic cod (Gadus morhua) from surveys conducted during March 1979–1988 were compared with concurrent measurements of bottom salinity, temperature and depth. Large catches of age 4 cod are more likely to occur in water characterized as the intermediate cold layer defined by salinities of 32–33.5 and temperatures<5°C. This relationship also appears to be modified by depth. We further show that internnual changes in the estimated abundance from the surveys were, in a number of cases, coincident with changes in the proportion of the bottom water composed of the intermediate cold water layer. The implications that these patterns may have on interpreting trends in the estimates of abundance from trawl surveys are discussed.     

Cognitive skills underlying driving in patients discharged following self-poisoning with central nervous system depressant drugs

Background: Central nervous system-depressant (CNS-Ds) drugs can impair cognitive functions and driving. They are also the most common drugs taken in overdose in hospital-treated episodes of self-poisoning. In Australia most of these patients are discharged within 48?h, while they still have possible subclinical drug effects. We aimed to determine whether patients treated for self-poisoning with CNS-Ds are impaired in the Trail-Making Test (TMT, parts A and B), a neuropsychological test that is known to correlate with driving performance. Methods: This study was a conducted from November 2008 to April 2011 in a referral center for poisonings in New South Wales, Australia. One hundred seven patients discharged from the clinical toxicology unit following treatment for self-poisoning of CNS-Ds (benzodiazepines, atypical antipsychotics, or opioids) and a control group of 68 discharged following self-poisoning of non-CNS-depressant drugs (acetaminophen or nonsedating antidepressants) were tested with the TMT (parts A and B). Due to the known association of impaired TMT with driving impairment and increased risk of traffic accidents, performance less than the 10th percentile for age was defined as significant impairment in each part of the TMT. The odds ratio (OR) for impairment in each part was calculated in multivariate logistic regression (MLR) models adjusted for gender, education, IQ, and the presence of a major psychiatric illness. A secondary MLR analysis was conducted only for those patients (78 CNS-D and 54 control group participants) who were directly discharged home, after excluding those who were transferred for further psychiatric care. Results: The odds of impairment in the CNS-D group was 2.8?times that of the control group on the TMT-A (38 [35.5%] vs. 11 [16.2%]: adjusted OR = 2.76, 95% confidence interval [CI]: 1.28-5.97), and 4.6?times on the TMT-B (67 [62.6%] vs. 22 [32.4%]: adjusted OR = 4.63, 95% CI: 2.06-10.42). The results were similar in the subgroup of patients discharged home, and the odds of impairment in the CNS-D group was 3.3?times that of the control group on the TMT-A (25 [32.1%] vs. 7 [13.0%]: adjusted OR = 3.30, 95% CI: 1.28-8.52), and 3.6?times on the TMT-B (46 [59.0%] vs. 17 [31.5%]: adjusted OR = 3.64, 95% CI: 1.44-9.20). TMT-B impairment in the CNS-D group remained significant even after adjusting for TMT-A performance. Conclusions: Patients with CNS-D overdose may have significant impairment in cognitive skills underlying driving at the time of discharge from hospitals. Clinicians should warn these patients that their driving skills might still be impaired, even if they are considered clinically recovered and advise them not to drive during the first 1 to 2?days following discharge.