Pesticide residues in birds at Lake Nakuru,Kenya

Specimens of three species of birds were collected from Lake Nakuru, Kenya, between September and October 1990. Samples of liver, kidney, muscle, fat and brain tissue were removed and analyzed for organochlorine pesticide residues. Fat was extracted and the content of three lindane (BHC/HCH) isomers (, and ), aldrin, heptachlor, heptachlorepoxide, endrin, dieldrin, DDD, DDE and DDT was determined. The samples contained varying residue levels of 12 organochlorine pesticides. No residues of 0, p'-DDD were detected. The most prevalent compounds were DDE and -BHC, found in 95.5 per cent and 66.4 per cent of the samples, respectively. The highest median residue concentration was 207 mg kg^–1×10^–3 of DDE in pelican fat tissue. White pelicanPelecanus onocrotalus, and the white-necked cormorant,Phalacrocorax carbo, showed greater concentrations of organochlorine residues than the lesser flamingo,Phoenicopterus minor. The mean DDE concentrations in pelican liver samples in 1970 and 1990 were 64 mg kg^–1×10^–3 and 274 mg kg^–1×10^–3, respectively. In cormorant liver samples the mean DDE concentration was 15 mg kg^–1×10^–3 in 1970 and 52 mg kg^–1×10^–3 in 1990. The mean DDE concentration in flamingo liver remained more or less similar at 2 mg kg^–1×10^–3 in 1970 and 1990.     

From Shiny Shoes to Muddy Reality: Understanding How Meso-State Actors Negotiate the Implementation Gap in Participatory Forest Management

Recent research on participatory forest management (PFM) in the global south has highlighted the existence of a widespread “implementation gap” between the ambitious intent enshrined in legislation and the often partial, disappointing rollout of devolved forest governance on the ground. Here, through an ethnographic case study of forest officers (FOs) in Kenya, we draw on a framework of critical institutionalism to examine how key meso-level actors, or “interface bureaucrats,” negotiate and challenge this implementation gap in everyday forest governance. We go beyond consideration of institutional bricolage in isolation or as an aggregate category, to analyze how bricolage as aggregation, alteration, and/or articulation is variously driven, shaped, and constrained by FOs’ multiple accountabilities and agency. Our analysis highlights the locally specific, contingent, and mutually reinforcing nature of accountability, agency and bricolage, and their explanatory power in relation to the performance and nature of “actually existing” PFM.     

Ecosystem service values of sediment generation and entrapment by marginal coral reefs at Sodwana Bay,South Africa

Coral reefs provide a multitude of goods and services, some of which are difficult to value due to their intangible nature and the absence of markets to ascribe their relative worth. The coral reefs of Sodwana Bay on the northeast coast of South Africa provide several ecological goods and services, of which only two are considered here: namely, sediment generation and sediment entrapment. Both are deemed essential to the functioning of the Sodwana Bay economy. The replacement-cost method was used to estimate the annual financial cost of sediment provided to the study area if it were replaced by dredging. Sediment generation by the coral reefs was valued at R2.6–R4.8 million, and sediment entrapment valued at R71.8–R84.6 million, totalling between R74.4 million and R89.4 million (≈$5.6–$6.7 million, at R13.38/US$1) per year.     

A review of methods for estimating evapotranspiration

The problems which characterize the study of evapotranspiration are briefly discussed. Different models which have been used for estimating evapotranspiration are reviewed. They include the eddy correlation model, mass transport model, aerodynamic model, Penman-resistance model and the energy balance model. The utilization of remote sensing for regional evapotranspiration estimation is discussed at length with case studies cited from USA, France, Germany and Kenya.     

Organochlorine pesticide and metal residues in a cichlid fish, Tilapia, Sarotherodon (=Tilapia) alcalicus grahami Boulenger from Lake Nakuru, Kenya

29 specimens of a cichlid fishSarotherodon (=Tilapia) alcalicus grahami were collected from Lake Nakuru between September and October 1990 and samples of liver, kidney, muscle, brain and fat were removed for analysis of organochlorine pesticide and metal residues. Fat was extracted and the concentration of three lindane (BHC/HCH) isomers (alpha, beta andgamma), aldrin, heptachlor, heptachlor-epoxide, endrin, dieldrin, DDD, DDE and DDT was determined. Fish muscle samples were digested and the concentration of mercury, arsenic and cadmium was also determined. No residues of o,p¹-DDD, p,p¹-DDD, aldrin, endrin and dieldrin were detected. The highest residue concentration detected was 0.062 mg kg⁻¹ of p,p¹-DDT. The mean pesticide residue concentration levels were generally low. The [p,p¹-DDT]/[p,p¹-DDE] ratio of 1.22 indicated that the residues of the parent DDT compound exist in the Lake Nakuru ecosystem. There was a negative fish length: DDE concentration relationship. Similarly, there was a very weak negative relationship between arsenic concentration and length of fish. The concentrations of metal residues were considerably low. The median arsenic and cadmium concentrations were 0.03 mg kg⁻¹ and <0.1 mg kg⁻¹, respectively. The concentrations of mercury, with a median level of <0.01 mg kg⁻¹, were particulary low and did not approach a level that would give rise to public health concern. Metal and pesticide residue concentration in fish in 1970 and 1990 does not show a significant increase. From these results, Lake Nakuru is presently not exposed to heavy pesticide and metal contamination, but there is a gradual build-up of these residues in the biota.     

Feasibility of CO<Subscript>2</Subscript> adsorption by solid adsorbents: a review on low-temperature systems

In the last few decades of industrialization, the concentration of CO₂ in the atmosphere had increased rapidly. Different organizations have invested considerable funds in research activities worldwide for CO₂ capture and storage. To date, significant work has been done and various technologies have been proposed for CO₂ capture and storage. Both adsorption and absorption are promising techniques for CO₂ capture, but low-temperature adsorption processes using solid adsorbents are the prevailing technique nowadays. In this review paper, a variety of adsorbents such as carbonaceous materials, dry alkali metal-based sorbents, zeolites, metal–organic frameworks (MOFs) and microporous organic polymers (MOPs) have been studied. Various methods of chemical or physical modification and the effects of supporting materials have been discussed to enhance CO₂ capture capacity of these adsorbents. Low-temperature (<100 °C) adsorption processes for CO₂ capture are critically analyzed and concluded on the basis of information available so far in the literature. All the information in CO₂ adsorption using different routes has been discussed, summarized and thoroughly presented in this review article. The most important comparative study of relatively new material MOFs and MOPs is carried out between the groups and with other sorbent as well.     

Chondrichthyans as an umbrella species-complex for conserving South African biodiversity

Conservation surrogates, such as umbrella and flagship species, could help focus South Africa’s limited resources for research and management and enhance the conservation gains from marine protected areas (MPAs). Sharks, rays and chimaeras (Chondrichthyes), which are charismatic and ecologically diverse, are potential umbrella candidates, but tests of the ecological suitability of putative marine umbrella species are lacking. Using baited remote underwater video in and around two MPAs in the Western Cape Province, we assessed the potential of chondrichthyans as an umbrella species-complex by quantifying the relationships and co-occurrence patterns between chondrichthyan abundance and diversity and those of other taxa (primarily teleosts and crustaceans). Sites with abundant chondrichthyans, with catsharks or large sharks (>1 m total length), all had significantly greater abundance and diversity of these other taxa, and associations with species of commercial and conservation interest (e.g. roman Chrysoblephus laticeps). Endemic scyliorhinids (notably dark catshark Haploblepharus pictus) and the broadnose sevengill shark Notorynchus cepedianus also had many strong positive co-occurrences (28% and 21% of interactions, respectively). The puffadder catshark H. edwardsii had the highest centrality of any species, denoting its high connectedness to other taxa. Overall, chondrichthyans, especially the dark and puffadder catsharks and the broadnose sevengill shark, show strong potential as an umbrella species-complex in South Africa.     

Radiation and energy flux characteristics of tea canopies in Kenya

This paper discusses the results of an experiment whereby all the major radiation and energy fluxes were measured/estimated for a mature tea canopy at Kericho, Kenya. The fluxes include incoming short-wave radiation, terrestrial radiation, latent heat flux and the sensible heat fluxes between the canopy and the air and that into and out of the soil. The pertinent data were simultaneously collected by use of 21X microloggers. Global radiation varied from 40 Wm^–2 to 1160 Wm^–2 depending on sky conditions. High values were observed early in the morning and late in the afternoon. Net radiation varied between — 100 Wm^–2 at night and 600 Wm^–2during the daytime. The largest proportion of net radiation was consumed by the latent heat flux. Advection was found to be minimal.