Grassland utopia and Silent Spring: Rereading the agrichemical revolution in New Zealand

Abstract:  This paper explores the post-World War II 'green revolution' in agricultural chemicals and its representation in Service , a New Zealand chemical industry journal. In particular, I describe how various 'texts' within the journal constructed the revolution largely in utopian terms. Critically rereading these texts reveals the extent to which chemical use in agriculture was tied to post-war discourses of unwavering optimism about science, technology and progress.     

Marine-like potash evaporite formation on a continental playa: case study from Chott el Djerid, southern Tunisia

An exceptional flood in January 1990 led to the formation of a large ephemeral lake on the Chott el Djerid, a salt playa in southern Tunisia. Repeated observations made during 1990 show that the ephemeral lake underwent four evolutionary stages: (1) initial flooding, (2) evaporative concentration of lake waters, (3) the movement of concentrated brine pools over the playa surface as a result of wind action, and (4) total desiccation of the lake by September 1990. During all four stages the brine chemistry of the lake was monitored. Water inflow into the Chott el Djerid basin was found to have a consistent Ca-SO₄-Cl-rich and HCO₃-CO₃-poor chemistry, reflecting the recycling of homogeneous assemblages of Cretaceous, Mio—Pliocene and Quaternary evaporites within the catchment. As the ephemeral lake shrank, these waters produced an Na-Mg-K-Cl-SO₄ brine which was similar to modern sea water. Mineral saturation data show that, during the desiccation of the lake, saturation with respect to both gypsum and halite was achieved and that the most concentrated brines were ultimately saturated with respect to potash phases. After the desiccation of the lake the main mineral phases found on the Chott included gypsum and halite. In addition, ephemeral deposits of carnallite (observed as carnallitite,3KMgCl_3·6H₂0 + NaCl) were found. This assemblage is that which would be expected to form if the waters had undergone salt norm evaporation at 1 bar pressure at 25°C (SNORM) in the evaporation model proposed by Jones and Bodine (1987). The nature of both the brine chemistry and evaporite mineralogy provides a new and rare example of marine-like potash-bearing evaporites being formed in a contemporary continental playa.     

High-frequency sediment-level oscillations in the swash zone

Sediment-level oscillations with heights of about 6 cm and shore-normal lengths of order 10 m have been measured in the swash zone of a high-energy, coarse-sand beach. Crests of oscillations were shore parallel and continuous alongshore. The oscillations were of such low steepness (height-to-length ratio approximately 0.006) that they were difficult to detect visually. The period of oscillation ranged between 6 and 15 min and decreased landward across the swash zone. The sediment-level oscillations were progressive landward with an average migration rate in the middle to upper swash zone of 0.8 m min⁻¹. Migration was caused mostly by erosion on the seaward flank of the crest of an oscillation during a period of net seaward sediment transport. Thus, the observed migration was a form migration landward rather than a migration involving net landward sediment transport. The observed sediment-level oscillations were different than sand waves or other swash-zone bedforms previously described.     

Effect of faceting on pore geometry in texturally equilibrated rocks: implications for low permeability at low porosity

The pore geometry of texturally equilibrated rocks is controlled by the interfacial energy ratio between grain boundaries and solid–liquid boundaries. Faceting at pore walls, which is a common feature of pore networks in rocks, strongly affects the liquid distribution. We investigated the effects of faceting on the equilibrium pore geometries based on image analysis of several systems with various degrees of faceting and dihedral angles. The degree of faceting was assessed by the F value, which is the ratio of the flat interface length at the pore wall to the length of total interfacial boundary between solid and liquid. The F values tend to increase with increasing liquid volume fraction. Little-faceted systems show relatively homogeneous liquid distribution. Moderately-faceted systems with a higher dihedral angle (∼55°) are characterized by development of large pores surrounded by faceted walls and complementary shrinkage of triple junction tubes, whereas strongly faceted systems with a low dihedral angle show no evidence of shrinking triple junction tubes, although most pores are surrounded by faceted pore walls. The faceted systems tend to produce more facet boundaries at the pore walls due to the difference of interfacial energies between the flat and curved surfaces. In the systems with the same degree of faceting, heterogeneity of liquid distribution tends to decrease with dihedral angle. For faceting systems, the permeability of texturally equilibrated rocks with low liquid fraction would be significantly decreased by the relative reduction of triple junction volumes or by closure of channels along grain edge due to the truncation of facet walls.     

Global Warming and Coastal Erosion

One of the most certain consequences of global warming is an increase of global (eustatic) sea level. The resulting inundation from rising seas will heavily impact low-lying areas; at least 100 million persons live within one meter of mean sea level and are at increased risk in the coming decades. The very existence of some island states and deltaic coasts is threatened by sea level rise. An additional threat affecting some of the most heavily developed and economically valuable real estate will come from an exacerbation of sandy beach erosion. As the beach is lost, fixed structures nearby are increasingly exposed to the direct impact of storm waves, and will ultimately be damaged or destroyed unless expensive protective measures are taken. It has long been speculated that the underlying rate of long-term sandy beach erosion is two orders of magnitude greater than the rate of rise of sea level, so that any significant increase of sea level has dire consequences for coastal inhabitants. We present in this paper an analytical treatment that indicates there is a highly multiplicative association between long-term sandy beach erosion and sea level rise, and use a large and consistent data base of shoreline position field data to show that there is reasonable quantitative agreement with observations of 19th and 20th century sea levels and coastal erosion. This result means that the already-severe coastal erosion problems witnessed in the 20th century will be exacerbated in the 21st century under plausible global warming scenarios.     

Urban Heat and Climate Justice: A Landscape of Thermal Inequity in Pinellas County,Florida

The combined effects of two global trends, urbanization and climate change, have generated considerable concern regarding their adverse and disproportionate impacts on the health of urban populations. This study contributes to climate‐justice research by determining whether elevated levels of urban heat, indicated by land surface temperature (LST), are distributed inequitably with respect to race/ethnicity, age, and socioeconomic status in Pinellas County, Florida. Our study utilizes 2010 MODIS and Landsat medium‐resolution, remotely sensed thermal data, census socio‐demographic information, and both conventional and spatial statistical methods. Results indicate that LST is significantly greater in census tracts characterized by higher percentages of certain racial/ethnic minorities and higher poverty rates, even after controlling for contextual factors and the effects of spatial autocorrelation. This reveals the presence of a landscape of thermal inequity: uneven distribution of heat within the built urban environment and a community structure with varying vulnerability.     

SrCa and MgCa ratios in polygenetic carbonate allochems from a Michigan marl lake

Rapid accumulation of CaCO₃ is occurring in Littlefield Lake, a marl lake located in central Michigan. The sediment, which is 95% CaCO₃, primarily consists of eight different genetic groups of carbonate allochems. These include calcite muds, sands, algal oncoids and Chara encrustations, as well as the dominant aragonitic gastropods Valvota tricarinota. Gyraulus deflectus and Amnicola integra. and the dominant aragonitic pelecypod Sphaerium partumeium. Samples of each of these groups were analyzed for Ca, Sr and Mg. Molar $\text{Mg}\text{Ca}$ ratios are primarily controlled by allochem mineralogy, with calcitic forms having $\text{Mg}\text{Ca}$ ratios 5–10 times larger than aragonitic (shelled) forms. The $\text{Sr}\text{Ca}$ ratios are primarily controlled by biochemical fractionation, and are significantly lower than $\text{Sr}\text{Ca}$ ratios of inorganically precipitated aragonite from other settings. Partition coefficients were determined for both Sr and Mg for each carbonate allochem group and, based on comparisons with results reported by other workers, the partition coefficients determined here are generally considered ‘typical’ or representative values for biogeneous freshwater carbonates. An analysis of variance of the data indicates that most genera and species of carbonate-secreting organisms in marl lakes have highly characteristic $\text{Sr}\text{Ca}$ and $\text{Mg}\text{Ca}$ ratios. These ratios can potentially serve as geochemical tracers in future investigations of lacustrine carbonate diagenesis. Both Sr and Mg are influenced by grain size and/or surface area, probably due to the presence of these elements in non-lattice-held (exchangeable) positions.     

Climate change, sea level rise and rice: global market implications

Climate change will influence yields while sea level rise can inundate producing lands. The research reported investigates the individual and simultaneous effects of these factors on production, trade and consumption of rice the world’s number one food crop. A global rice trade model is utilized to do this. The results indicate that the combination of yield and sea level effects causes a significant reduction in production and an increase in rice prices which may have important policy implications for food security. Global rice production is reduced by 1.60% to 2.73% while global rice price increases by 7.14% to 12.77%. Sea level rise is particularly a risk factor in Bangladesh, Japan, Taiwan, Egypt, Myanmar and Vietnam. In the face of such developments, adaptation may well be desirable and thus an investigation is done over adaptation options of increased technical progress or trade liberalization with the results showing that both can mitigate such damages.