Reducing fluxes of faecal indicator compliance parameters to bathing waters from diffuse agricultural sources: the Brighouse Bay study, Scotland

The European Water Framework Directive requires the integrated management of point and diffuse pollution to achieve 'good' water quality in 'protected areas'. These include bathing waters, which are regulated using faecal indicator organisms as compliance parameters. Thus, for the first time, European regulators are faced with the control of faecal indicator fluxes from agricultural sources where these impact on bathing water compliance locations. Concurrently, reforms to the European Union (EU) Common Agricultural Policy offer scope for supporting on-farm measures producing environmental benefits through the new 'single farm payments' and the concept of 'cross-compliance'. This paper reports the first UK study involving remedial measures, principally stream bank fencing, designed to reduce faecal indicator fluxes at the catchment scale. Considerable reduction in faecal indicator flux was observed, but this was insufficient to ensure bathing water compliance with either Directive 76/160/EEC standards or new health-evidence-based criteria proposed by WHO and the European Commission.     

Environmental controls on the landscape-scale biogeography of stream bacterial communities

We determined the biogeographical distributions of stream bacteria and the biogeochemical factors that best explained heterogeneity for 23 locations within the Hubbard Brook watershed, a 3000-ha forested watershed in New Hampshire, USA. Our goal was to assess the factor, or set of factors, responsible for generating the biogeographical patterns exhibited by microorganisms at the landscape scale. We used DNA fingerprinting to characterize bacteria inhabiting fine benthic organic matter (FBOM) because of their important influence on stream nutrient dynamics. Across the watershed, streams of similar pH had similar FBOM bacterial communities. Streamwater pH was the single variable most strongly correlated with the relative distance between communities (Spearman's p = 0.66, P < 0.001) although there were other contributing factors, including the quality of the fine benthic organic matter and the amount of dissolved organic carbon and nitrogen in the stream water (P < 0.05 for each). There was no evidence of an effect of geographic distance on bacterial community composition, suggesting that dispersal limitation has little influence on the observed biogeographical patterns in streams across this landscape. Cloning and sequencing of small-subunit rRNA genes confirmed the DNA fingerprinting results and revealed strong shifts among bacterial groups along the pH gradient. With an increase in streamwater pH, the abundance of acidobacteria in the FBOM bacterial community decreased (from 71% to 38%), and the abundance of proteobacteria increased (from 11% to 47%). Together these results suggest that microorganisms, like "macro"-organisms, do exhibit biogeographical patterns at the landscape scale and that these patterns may be predictable based on biogeochemical factors.     

Causes and consequences of unequal seedling production in forest trees: a case study in red oaks

Inequality in reproductive success has important implications for ecological and evolutionary dynamics, but lifetime reproductive success is challenging to measure in long-lived species such as forest trees. While seed production is often used as a proxy for overall reproductive success, high mortality of seeds and the potential for trade-offs between seed number and quality draw this assumption into question. Parentage analyses of established seedlings can bring us one step closer to understanding the causes and consequences of variation in reproductive success. In this paper we demonstrate a new method for estimating individual seedling production and average percentage germination, using data from two mixed-species populations of red oaks (Quercus rubra, Q. velutina, Q. falcata, and Q. coccinea). We use these estimates to examine the distribution of female reproductive success and to test the relationship between seedling number and individual seed production, age, and growth rate. We show that both seed and seedling production are highly skewed, roughly conforming to zero-inflated lognormal distributions, rather than to the Poisson or negative-binomial distributions often assumed by population genetics analyses. While the number of established offspring is positively associated with mean annual seed production, a lower proportion of seeds from highly fecund individuals become seedlings. Our red oak populations also show evidence of trade-offs between growth rate and reproductive success. The high degree of inequality in seedling production shown here for red oaks, and by previous studies in other species, suggests that many trees may be more vulnerable to genetic drift than previously thought, if immigration in limited by fragmentation or other environmental changes.     

The relationship between persistent organic pollutants in maternal and neonatal tissues and immune responses to allergens: A novel exploratory study

BACKGROUND: Modern persistent organic pollutants (POPs) contamination are logical candidates in the investigation of the, as yet, unexplained association between allergic disease and progressive industrialisation. POPs have been detected in human cord blood, placental tissues and breast milk, and the reported association between cord blood IgE levels and cord/placental POP levels has raised concerns about potential immunological effects in early life. METHODS: The initial aim of this study was to determine if POPs were detectable in maternal blood, cord blood, placental tissues, adipose tissue and breast milk samples from randomly selected Western Australian women (n = 31), where allergic disease is epidemic. Gas chromatography was used to detect polychlorinated biphenyl compounds [PCBs] (as Aroclor 1232, 1254, 1260) and organochlorine (OC) pesticides, including p,p'-DDT, p,p'-DDE, hexachlorobenzene (HCB), lindane, heptachlor epoxide, dieldrin and chlordane. Secondly, we assessed the relationship between POP levels detected in vivo and maternal and neonatal responses (cytokine and lymphoproliferation) to allergens and mitogens. RESULTS: Low level POP contamination was detected in adipose tissue and breast milk (but not in cord blood, maternal blood or placental tissues). The most ubiquitous compound found in over 90% of adipose tissues samples was a OC metabolite of DDT, p,p'-DDE (median 0.07 mg/kg; interquartile range [IQR] 0.05-0.12). However, the majority of other OC compounds were not detectable and PCB were not detectable in any samples. The three main residues detected in breast milk were p,p'-DDE (0.003 mg/l; 0.001-0.009), dieldrin (0.001 mg/l; 0.001-0.046) and HCB (0.001 mg/l; 0.001-0.001). These levels are significantly lower than reported over 20 years ago. There were no consistent relationships between POP levels in vivo and maternal or infant responses, with the exception of a significant inverse association (Spearman rank correlation: r = -0.406, p = 0.049) between maternal adipose tissue levels of OC p,p'-DDE and maternal T helper cell Type 1 interferon [IFN] gamma to mitogens. CONCLUSION: This study provides the first evidence (in Australia) since the early 1990's that adipose OC levels have continued to fall. The negligible levels in this randomly selected group are significantly lower than those previously recorded, suggesting that POP contamination (at biologically relevant levels) is not likely to be a major contributing factor in the increasing rates of allergy in Western Australia. However, the relationship between Th1 immune function and OC contamination is consistent with other reports and is worth investigating as a relevant factor in populations where OC contamination is greater.     

Integrated assessment modeling of atmospheric pollutants in the Southern Appalachian Mountains: Part II. Fine particulate matter and visibility

As part of the Southern Appalachian Mountains Initiative, a comprehensive air quality modeling system was developed to evaluate potential emission control strategies to reduce atmospheric pollutant levels at the Class I areas located in the Southern Appalachian Mountains. Six multiday episodes between 1991 and 1995 were simulated, and the skill of the modeling system was evaluated. Two papers comprise various parts of this study. Part I details the ozone model performance and the methodology that was used to scale discrete episodic pollutant levels to seasonal and annual averages. This paper (part II) addresses issues involved with modeling particulate matter (PM) and its relationship to visibility. For most of the episodes, the fractional error was approximately 50% or less for the major constituents of the fine PM (i.e., sulfate [SO4] and organics) in the region. The mean normalized errors and fractional errors are generally larger for the NO3 and soil components, but these components are relatively small. Variations in modeling bias with pollutant levels were also examined. The model showed a systematic overestimation for low levels and an underestimation for high levels for most PM species. For ammonium, the model showed better performance at lower SO4 concentrations when the measured SO4 was assumed to be completely neutralized (ammonium sulfate) and better performance at higher SO4 concentrations when the partially neutralized (ammonium bisulfate) assumption was made. The contributions of various components of PM to reductions in visibility were also calculated; SO4 was found to be the major contributor.     

Bermudagrass management in the southern Piedmont, USA: IX. Trace elements in soil with broiler litter application

An understanding of the long-term cycling of trace elements in soil with broiler litter fertilization under various forage utilization strategies is needed to develop sustainable agricultural production systems. We evaluated differences in Cu, Mn, Zn, and six other trace elements in response to 5 yr of bermudagrass [Cynodon dactylon (L.) Pers.] management varying in fertilization and harvest strategies on a Typic Kanhapludult in Georgia. Chicken (Gallus gallus) broiler litter was a significant source of trace elements that led to 3.4 +/- 0.5 times higher Cu, 2.0 +/- 0.3 times higher Mn, and 2.1 +/- 0.2 times higher Zn in the surface 3 cm of soil than when forage was fertilized inorganically. There were variable effects of broiler litter fertilization on other trace elements, depending upon element, depth of sampling, and forage utilization strategy. Concentrations of all trace elements in soil were below levels considered toxic to plants. Soil at a depth of 0 to 3 cm under grazed paddocks had 33 +/- 5% greater Cd, 18 +/- 1% greater Cr, 53 +/- 24% greater Cu, and 24 +/- 7% greater Zn compared with unharvested and hayed management. Trace elements in soil were unaffected whether forage was unharvested or removed as hay. These results suggest that broiler litter is a significant source of several trace elements and that ruminant processing of forage and subsequent deposition of excreta on the paddock allow these trace elements to accumulate more at the soil surface where they might interact with the high concentration of organic matter.