Environmental Analysis 33


There are many enviro nmental and physiological factors that affect photosynthesis and the latest gas exchange instrumentation is de-signed to enable researchers to analyse these parameters in relation to CO2 uptake.


Researcher from University of Aberdeen investigating photosynthesis using the ADC LCi.


The ADC BioScientific LCi and LCpro+ are two truly portable photosynthesis systems designed to carry out these experiments even in the most remote and harsh field locations. To ensure the fastest possible response times, a miniaturised IRGA is positioned directly next to the chamber where the leaf is analysed. With ambient air being circulated around the


system a CO2 measurement is performed prior to the air flow reaching the leaf and then again after the leaf. The difference in the CO2


concentration is therefore due to the activity of the leaf.


Both the LCi and the LCpro+ are battery operated systems providing up to 16 hours of continuous operation from a single charge. To analyse environmental effects of photosynthesis the LCpro+ is able to automatically control the temperature, light, water vapour and particularly CO2, at elevated levels (>700ppm), within the leaf chamber.


Plant response to elevated CO2 is also conducted at whole plant level, where CO2 is elevated (>700ppm) inside open-top chambers. These tent like structures are several meters high and in diameter allowing a researcher to analyse photosynthetic activity using the LCi or


LCpro+ directly inside the chamber. Free Air CO2 Enrichment experiments (FACE) elevate CO2 in field sites, up to 30m in diameter, using a ring of enrichment pipes. This allows investigations of whole


undisturbed ecosystems without modifying the vegetation interaction with the natural environment.


Soil Respiration


Soil respiration or soil CO2 flux is the largest natural carbon source. It is therefore extremely important to understand its process, the effects of environmental conditions and the role it plays in global carbon cycling.


Soil respiration consists of CO2 produced by respiring soil micro-organisms during the degradation of soil biomass material. There is additional respiration from plant root tissue.


There are two major types of field soil respiration experimentation. Spatial variability consists of short-term measurements taken at a number of different sample points across a field site during a limited time period. Instrumentation for this type of work includes the ADC BioScientific


SRS1000 and SRS2000. These truly field portable systems feature a CO2 IRGA located directly next to a soil respiration chamber. As with the


photosynthesis systems CO2 concentrations are measured before and after the soil chamber to ascertain the CO2 flux rates from the soil. The soil chamber features a detachable stainless steel collar that is placed


Carbon dioxide cycle


AUTHOR DETAILS Roy Newman


ADC BioScientific Ltd 1st Floor, Charles House Furlong Way Great Amwell Herts, SG12 9TA Tel: +44 (0)1920 487901 Fax: +44 (0)1920 466289 Email: sales@adc.co.uk Web: www.adc.co.uk


into the soil several minutes prior to the start of measurements. By having a number of collars placed around a field site multiple soil flux determinations can be made and so spatial variability can be determined.


The second major type of field soil flux experimentation is temporal variability when flux rate changes are monitored daily, monthly or even yearly on the same area of soil.


For temporal variability research ADC BioScientific has developed


ACE (Automated Soil CO2 Exchange System) which has been designed for long-term unattended soil flux measurements. Each ACE Station


features a highly accurate CO2 IRGA housed directly next to the soil chamber, thus reducing response times, making the system easy to set up, field robust and very power efficient. Measurements are typically


made once an hour by measuring the rise in CO2 concentrations inside the chamber. The chamber then automatically opens between analysis cycles so allowing ambient conditions to reach the soil.


Multiple ACE Stations can be used independently or as part of an ACE Network. Up to 30 ACE Stations can be electrically connected together, allowing programming, data storage and power supply via a single ACE Master Control Unit.


There is a high level of scientific confidence that atmospheric CO2 concentrations are increasing and that global temperatures are rising.


However, many knowledge gaps remain regarding the processes and interactions within the carbon cycle. Therefore there are continuing expectations from the world’s scientific community for manufacturers to develop ever more sophisticated and field portable gas exchange equipment. ADC BioScientific will continue to endeavour to meet these challenges.


ADC ACE system in use at Slovak Agricultural University, Nitra, Slovakia.


Positive Material Identification (PMI) On-site XRF Analyser


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The Innov-X tube-based Alpha Series is isotope free and delivers instant, accurate readings. It features a miniature X-ray tube and high-resolution detector. Engineered around the HP iPAQ pocket PC, the Alpha Series is user-friendly, flexible, and upgradeable, and has a bright color display for easy viewing in all lighting conditions and a rear-facing LCD display. It is now available for rental at Ashtead Technology (SEA) Pte Ltd. Contact us at asia@ashtead-technology.com


Reader Reply Card no 94 New Compact Digesters


VELP Scientifica (Italy) launches its new DKL Series Digesters with outstanding practical features. Remember that the sample preparation is crucial in order to obtain better results, and with DKL Series you can perform it in the optimum way. The space-saving design, requiring minimal lab bench space, manages to incorporate full functionality in a greatly reduced footprint. The units are supplied with a complete set of accessories as standard, enabling the operator to start operation immediately, achieving results accepted by all the world’s leading analytical organizations and the unit offers conformity to standards such as AOAC, EPA, DIN and ISO.


VELP DKL Series offers exceptional temperature precision and stability – all of ± 0.5°C for all the samples, allowing a complete and homogeneous digestion and covering a temperature range from ambient to 450°C. Units accept 8 standard 250ml, 12 of 250 / 400ml, 20 of 250ml or 42 of 100ml digestion tubes. Ease of loading and unloading make the VELP DKL Digesters a pleasure to use when carrying out Kjeldahl analysis.


Reader Reply Card no 95 Reader Reply Card no 96


August/September 2010 AET


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