Multivariate analysis of spatial patterns: a unified approach to local and global structures

We propose a new approach to the multivariate analysis of data sets with known sampling site spatial positions. A between-sites neighbouring relationship must be derived from site positions and this relationship is introduced into the multivariate analyses through neighbouring weights (number of neighbours at each site) and through the matrix of the neighbouring graph. Eigenvector analysis methods (e.g. principal component analysis, correspondence analysis) can then be used to detect total, local and global structures. The introduction of the D-centring (centring with respect to the neighbouring weights) allows us to write a total variance decomposition into local and global components, and to propose a unified view of several methods. After a brief review of the matrix approach to this problem, we present the results obtained on both simulated and real data sets, showing how spatial structure can be detected and analysed. Freely available computer programs to perform computations and graphical displays are proposed.     

Assessing environmental impacts of treated wastewater through monitoring of fecal indicator bacteria and salinity in irrigated soils

To assess the potential for treated wastewater irrigation to impact levels of fecal indicator bacteria (FIB) and salinity in irrigated soils, levels of Escherichia coli, Enterococcus, and environmental covariates were measured in a treated wastewater holding pond (irrigation source water), water leaving the irrigation system, and in irrigated soils over 2 years in a municipal parkland in Arizona. Higher E. coli levels were measured in the pond in winter (56 CFU 100 mL⁻¹) than in summer (17 CFU 100 mL⁻¹); however, in the irrigation system, levels of FIB decreased from summer (26 CFU 100 mL⁻¹) to winter (4 CFU 100 mL⁻¹), possibly related to low winter water use and corresponding death of residual bacteria within the system. For over 2 years, no increase in FIB was found in irrigated soils, though highest E. coli levels (700 CFU g⁻¹ soil) were measured in deeper (20–25 cm) soils during summer. Measurements of water inputs vs. potential evapotranspiration indicate that irrigation levels may have been sufficient to generate bacterial percolation to deeper soil layers during summer. No overall increase in soil salinity resulting from treated wastewater irrigation was detected, but distinct seasonal peaks as high as 4 ds m⁻¹ occurred during both summers. The peaks significantly declined in winter when surface ET abated and more favorable water balances could be maintained. Monitoring of seasonal shifts in irrigation water quality and/or factors correlated with increases and decreases in FIB will aid in identification of any public health or environmental risks that could arise from the use of treated wastewater for irrigation.     

Source apportionment of urban fine and ultra-fine particle number concentration in a Western Mediterranean city

Extensive measurements on particle number concentration and size distribution (13–800 nm), together with detailed chemical composition of PM_2.5 have constituted the main inputs of the database used for a source apportionment analysis. Data were collected at an urban background site in Barcelona, Western Mediterranean.The source identification analysis helped us to distinguish five emission sources (vehicle exhausts, mineral dust, sea spray, industrial source and fuel-oil combustion) and two atmospheric processes (photochemical induced nucleation and regional/urban background particles derived from coagulation and condensation processes). After that, a multilinear regression analysis was applied in order to quantify the contribution of each factor.This study reveals that vehicle exhausts contribute dominantly to the number concentration in all the particle sizes (52–86%), but especially in the range 30–200 nm. This work also points out the importance of the regional and/or urban formed aerosols (secondary inorganic particles) on the total number concentration (around 25% of the total number), with a higher impact on the accumulation mode. The photo-chemically induced nucleation of aerosols only represents a small proportion of the total number as an annual mean (3%), but is very relevant when considering only the nucleation mode (13–20 nm) fraction (23%). The other sources recognized registered sporadic contributions to the total number, coinciding with specific meteorological scenarios.This study discloses the main sources and features affecting and controlling the fine and ultra-fine aerosols in a typical city in the Western Mediterranean coast. Whereas the road traffic appears to be the most important source of sub-micrometric aerosols, other sources may not be negligible under specific meteorological conditions.     

Serum concentrations of perfluorooctanesulfonate and other fluorochemicals in an elderly population from Seattle, Washington

Perfluorooctanesulfonyl fluoride (POSF, C₈F₁₇SO₂F) related-materials have been used as surfactants, paper and packaging treatments, and surface (e.g., carpet, textile, upholstery) protectants. A metabolite, perfluorooctanesulfonate (PFOS, C₈F₁₇SO₃⁻), has been identified in the serum and liver of non-occupationally exposed humans and wildlife. Because of its persistence, an important question was whether elderly humans might have higher PFOS concentrations. From a prospective study designed to examine cognitive function in the Seattle (WA) metropolitan area, blood samples were collected from 238 dementia-free subjects (ages 65–96). High-pressure liquid chromatography-electrospray tandem mass spectrometry determined seven fluorochemicals: PFOS; N-ethyl perfluorooctanesulfonamidoacetate; N-methyl perfluorooctanesulfonamidoacetate; perfluorooctanesulfonamidoacetate; perfluorooctanesulfonamide; perfluorooctanoate; and perfluorohexanesulfonate. Serum PFOS concentrations ranged from less than the lower limit of quantitation (3.4 ppb) to 175.0 ppb (geometric mean 31.0 ppb; 95% CI 28.8–33.4). An estimate of the 95% tolerance limit was 84.1 ppb (upper 95% confidence limit 104.0 ppb). Serum PFOS concentrations were slightly lower among the most elderly. There were no significant differences by sex or years residence in Seattle. The distributions of the other fluorochemicals were approximately an order of magnitude lower. Similar to other reported findings of younger adults, the geometric mean serum PFOS concentration in non-occupational adult populations likely approximates 30–40 ppb with 95% of the population’s serum PFOS concentrations below 100 ppb.     

Impact assessment of climate change on farming systems in the South Mediterranean area: a Tunisian case study

Regional Environmental Change - This study considers a quantitative approach for assessing the performance of Tunisian farming systems to face climate change. It is based on the resilience concept...     

Analyzing the hydrologic effects of region-wide land and water development interventions: a case study of the Upper Blue Nile basin

In the drylands of the Upper Blue Nile basin, high climate variability and land degradation are rampant. To enhance adaptive capacity in the region, various soil and water conservation interventions have been implemented. Moreover, water resources development schemes such as the Grand Ethiopian Renaissance Dam should be implemented by 2025. We modeled the effects of these interventions on surface runoff in the basin for both current and future (2025) basin conditions, using the runoff coefficient method in a spatially explicit approach. Under current conditions, we observed high spatial variability of mean annual runoff. The northeastern Blue Nile-1 sub-basin produces the highest mean annual runoff (391 mm or 10 × 10⁹ m³), whereas the northwestern Blue Nile-2 sub-basin produces the lowest mean annual runoff (178 mm or 0.2 × 10⁹ m³). The basin generates a total annual runoff volume of 47.7 × 10⁹ m³, of which about 54 % comes from cultivated land. The strong association between land use and topography masked the direct effect of rainfall on runoff. By 2025, total annual runoff yield could decrease by up to 38 % if appropriate basin-wide soil and water conservation interventions and the Grand Ethiopian Renaissance Dam are implemented. However, the full effects of most physical structures will only last for 1 or 2 years without regular maintenance. The improved understanding of the dynamics of the Upper Blue Nile basin’s hydrology provided by the present study will help planners to design appropriate management scenarios. Developing the basin’s database remains important for a holistic understanding of the impacts of future development interventions.     

农户庭院型生态工艺原位处理源分离后的洗涤废水

选择长江三角洲地区有一定代表性的乡村家庭,开展了厌氧池-多级布水模块化人工湿地原位处理源分离后的废水的实例研究,旨在掌握乡村家庭源分离后废水的水质特征,并通过厌氧池-多级布水模块化人工湿地,重点解决乡村家庭源分离后的废水原位净化达标排放问题。结果表明,耗氧有机物(以COD计)、BOD₅、LAS (linear alkylbenzene sulfonates)是洗涤废水、灰水中的主要污染物质;季节变化、进水浓度对厌氧池-多级布水模块化人工湿地处理源分离后的废水中的耗氧有机物、LAS影响不显著,但季节变化对粪大肠菌群影响显著。总体上,2户农户的设施出水均符合《农田灌溉水质标准》(GB 5084-2005)水作作物的相关规定。     

Precipitation of swine and cattle manure phosphorous using limestone dust

The effectiveness of SPS and PULPRO, fine limestone dusts, in precipitating swine and dairy manure phosphorous (P) was determined in the laboratory. Both manures were sieved before being treated with limestone, to reproduce the treatment of mechanically separated manure and to observe the precipitation effect of limestone without that of the large manure solid particles. P precipitation was optimized by varying precipitation conditions (propeller blade speeds, mixing time and limestone levels) and limestone particle size. P precipitation was optimized using a propeller blade mixing speed of 0.3 m s(-1) for at least 5 minutes, using 3% limestone (dry limestone mass over wet manure mass). In terms of particle size, PULPRO 20 (limestone with a particle size of 0.02 mm) produced the most P precipitation and the smallest volume and mass of sludge, as compared to PULPRO 10, PULPRO 3 and SPS (limestone with a particle size of 0.01, 0.003 and 0.3 to 0.003 mm, respectively). For both 9.5% TS (total solids) dairy and 8.8% TS swine manure, mechanical separation followed by limestone precipitation concentrated 90% of manure TS and TP in a sludge volume representing 45% of the initial raw manure mass.