Environmental prediction, risk assessment and extreme events: adaptation strategies for the developing world

Relation between various soil phosphorus extraction methods and sorption parameters in calcareous soils with different texture

The aim of this study was to investigate the influence of soil texture on phosphorus (P) extractability and sorption from a wide range of calcareous soils across Hamedan, western Iran. Fifty seven soil samples were selected and partitioned into five types on the basis of soil texture (clay, sandy, sandy clay loam, sandy loam and mixed loam) and the P extracted with calcium chloride (PCaCl2), citrate (Pcitrate), HCl (PHCl), Olsen (POls), and Mehlich-3 (PM3) solutions. On the average, the P extracted was in the order PHCl>PM3>Pcitrate>POls>PCaCl2. The P extracted by Pcitrate, PHCl, POls, and PM3 methods were significantly higher in sandy, sandy clay loam and sandy loam textures than clay and mixed loam textures, while soil phosphorus buffer capacity (PBC) was significantly higher in clay and mixed loam soil textures. The correlation analysis revealed a significant positive relationship between silt content Freundlich sorption coefficient (KF), maximum P sorption (Qmax), linear distribution coefficient (Kd), and PBC. All extractions were highly correlated with each other and among soil components with silt content. The principal component analysis (PCA) performed on data identified five principal components describing 74.5% of total variation. The results point to soil texture as an important factor and that silt was the crucial soil property associated with P sorption and its extractability in these calcareous soils. DPSM3-2 (PM3PM3+Qmax×100) and DPScitrate (PcitratePcitrate+Qmax×100) proved to be good indicators of soil's potential P release in these calcareous soils. Among the DPS, 21% of soils reported DPSM3-2, values higher than the environmental threshold, indicating build-up of P and P release. Most of the studied sandy clay loam soils had exceeded the environmentally unacceptable P concentration. Various management practices should be taken into account to reduce P losses from these soils. Further inorganic and organic P fertilizer inputs should be reduced in some parts of studied area.

Potential phosphorus and arsenic mobilization from Bangladesh soils by particle dispersion

Besides dissolution, particle dispersion and mobilization can substantially contribute to element transfer from soils to waters. The dispersibility of the fine particulate and the associated potential losses of P and As from Bangladesh soils of the Ganges and Meghna floodplains have been evaluated with a simple dispersion test. The dispersible fraction was greater for the coarse-textured soils from the Meghna floodplain and increased with particle charge density. Particulate phosphorus (PP) and As (PAs) were the dominant forms in the dispersion, dissolved P and As being scarce to negligible. The PP and PAs were related to the amount of dispersed particulate, oxalate-extractable iron and, respectively, to the water-extractable P or phosphate-extractable As. Although reductive dissolution is reported as the main mechanism of As mobilization during prolonged monsoon flooding, the transfer in particulate form could potentially represent a major pathway for P and As transfer from soils to waters in oxic environments after sudden, extreme events. Since the frequency of extreme rainfall and floods is increasing because of the climate changes, and the intensified land cultivation is enhancing soil disturbance, larger contributions of particulate runoff to element migration from soils to waters could be expected in the future.

Integrating climate change adaptation into public health practice: using adaptive management to increase adaptive capacity and build resilience

BACKGROUND

Climate change is expected to have a range of health impacts, some of which are already apparent. Public health adaptation is imperative, but there has been little discussion of how to increase adaptive capacity and resilience in public health systems.

OBJECTIVES

We explored possible explanations for the lack of work on adaptive capacity, outline climate-health challenges that may lie outside public health's coping range, and consider changes in practice that could increase public health's adaptive capacity.

METHODS

We conducted a substantive, interdisciplinary literature review focused on climate change adaptation in public health, social learning, and management of socioeconomic systems exhibiting dynamic complexity.

DISCUSSION

There are two competing views of how public health should engage climate change adaptation. Perspectives differ on whether climate change will primarily amplify existing hazards, requiring enhancement of existing public health functions, or present categorically distinct threats requiring innovative management strategies. In some contexts, distinctly climate-sensitive health threats may overwhelm public health's adaptive capacity. Addressing these threats will require increased emphasis on institutional learning, innovative management strategies, and new and improved tools. Adaptive management, an iterative framework that embraces uncertainty, uses modeling, and integrates learning, may be a useful approach. We illustrate its application to extreme heat in an urban setting.

CONCLUSIONS

Increasing public health capacity will be necessary for certain climate-health threats. Focusing efforts to increase adaptive capacity in specific areas, promoting institutional learning, embracing adaptive management, and developing tools to facilitate these processes are important priorities and can improve the resilience of local public health systems to climate change.