Calcareous termite mounds in South Africa are ancient carbon reservoirs.

Ecosystems that offer carbon sequestration by leaching bicarbonate to groundwater are valuable natural capital. One region that may offer this service is the west coast of South Africa. Over 20 % is covered by soil mounds ("heuweltjies") up to 40 m diameter, 2 m high, inhabited by the southern harvester termite Microhodotermes viator and enriched in soil organic and inorganic carbon and soluble minerals. We aimed to generate radiogenic and stable isotope data for soils and groundwater in a region where these data are absent, to 1) verify the atmosphere-soil-groundwater link, and 2) resolve the timing and pattern of calcite dissolution and water infiltration in the landscape. Results show that soil and groundwater sulfate have the same marine aerosol source. Episodic calcite dissolution in mound centers, which increased during periods of global cooling, has been set against background input of marine aerosols since before the Last Glacial according to radiocarbon (14C) ages. Our data push back soil organic carbon 14C ages of inhabited termite mounds to 13-19 ka (kiloannum, thousand years before present), nest carbonate 14C ages to 33 ka, and mound soil carbonate 14C ages to 34 ka, making these the oldest active termite features ever dated. These ages are consistent with soil organic carbon and carbonate 14C ages of regional, non-mound, coastal petrocalcic horizons formed by accumulation of carbonate leached from their overlying aeolian dune fields. Harvesting activities of termites inject younger organic material around nests >1 m deep, leading to continuous renewal of important soil carbon reservoirs at depth. Termite bioturbation increases the system's ability to dissolve carbonate. The central, bioturbated part of the mounds have greater infiltration depths and greater calcite dissolution, whereas surrounding soils experienced more surface runoff. Calcareous termite mounds offer a mechanism to sequester CO2 through dissolution and leaching of soil carbonate-bicarbonate to groundwater.

Saline groundwater in the Buffels River catchment, Namaqualand, South Africa: A new look at an old problem.

Namaqualand, South Africa, is a global biodiversity hotspot but local populations are affected by challenging economic conditions largely because of poor access to water. In this study groundwater types are characterised and sources of salts and salinisation processes are identified using hydrochemistry and δ18O, δ2H and 87Sr/86Sr data. Analysis of δ18O and δ2H data suggests that evaporation does not play a major role in salinisation of the groundwater. However, major ion chemistry and 87Sr/86Sr ratios indicate that salts present in the groundwater are linked to dry deposition of marine aerosols and ion-exchange reactions in soils in the alluvial aquifer systems. The hydrochemical variability of the groundwater in the basement aquifer system suggests that there are strong local controls linked to weathering processes in individual basement rock types. The region is also notable for the high density of heuweltjies, biophysical features associated with increased nutrient levels, associated with termite activity. Electromagnetic scanning as well as measurement of water-soluble soil electrical conductivity values on and off heuweltjies, show that heuweltjies are saline with salinity increasing with depth. The level of groundwater salinity correlates with the level of heuweltjie salinity. Precipitation records from the last 150 years provide support for the hypothesis that accumulated salts, and in particular, heuweltjie salts are flushed into the groundwater system during sporadic large volume precipitation events. Thus, heuweltjies and hence termite activity, could potentially represent a previously unrecognized contributor to groundwater salinisation across Namaqualand and in other parts of the world.

[Quality improvement project 'laboratory diagnosis by family physicians' leads to considerable decrease in number of laboratory tests]. / Kwaliteitsverbeteringsproject 'laboratoriumdiagnostiek door huisartsen' leidt tot aanzienlijke reductie van het aantal laboratoriumanalysen.

OBJECTIVE: Quality improvement of laboratory diagnostics by general practitioners (GPs) through introduction of a simplified, problem-oriented application form, supported by information and feedback. DESIGN: Prospective descriptive study. SETTING: Laboratory of Clinical Chemistry and Haematology of St. Maartens Gasthuis, Venlo, the Netherlands and the GPs in the region. METHODS: The effects of the intervention were measured by counting the analyses requested by all GPs in the region in 1992, 1993 and 1994. Furthermore requests by every GP for fifteen selected analyses in the first 6 months of 1992, 1993 and 1994 were counted and reported together with the anonymous data of all colleagues. RESULTS: After the intervention a 23% reduction of the total number of analyses request by GPs was noticed. Blood sampling increased by 8% and the mean number of laboratory test requests per patient decreased from 5.9 to 4.2. The largest request reductions were noticed for analyses not listed on the application form. Measurements in the first 6 months of 1992, 1993 and 1994 showed continuation of the trend and a fadeaway of 'redundant' analyses. CONCLUSION: The introduction of a simplified problem-oriented application form for GPs supported by feedback caused a marked decrease of the number of (redundant) laboratory requests.

A programme for post-graduate training and quality control in blood cell morphology.

The programme presented can be considered as a combination of permanent education with quality control carried out on a regional level. The selection procedure of blood smears for distribution will be discussed. The sensitivity and specificity are tested of many frequently occurring haematological abnormalities.

Fresh human blood as the source of a regional quality survey programme in haematology.

In a regional quality survey programme in haematology with a limited number of participants (15 in the region described), it appeared possible to use unpreserved, fresh, EDTA-anticoagulated blood samples. With such samples only the results from hospital laboratories with different instruments and methods could adequately be compared. From the results of single analyses obtained in ten different samples, the systematic differences as well as the precision of the analyses were calculated for each hospital laboratory with respect to haemoglobin, packed cell volume, red blood cell count, white blood cell count, and platelet count.