School of Earth and Environment: Earth SciencesSchool of Earth and Environment: Earth SciencesProf. Michael KromEnvironmental Geochemistry Email: M.D.Krom@leeds.ac.uk |
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I am Director of the Leeds Earth and Biosphere Institute. This institute is dedicated to promoting interdisciplinary science across the area Environmental science, Biodiversity and conservation and is an important part of the University Gold peak of excellence of Earth and Environmental Systems Science. I am also a member of the Steering committee of water@leeds, an interdepartmental grouping at Leeds University dedicated to excellence in research across the area of pure and applied aquatic science.
 Satellite image of the Eastern Mediterranean showing the transition between winter ‘bloom’ conditions and summer nutrient starved conditions. |
The Eastern Mediterranean is unusual in two particular ways; it is ultra-oligotrophic with very low primary productivity despite the input of significant amounts of nutrients from the adjacent land-masses particularly Europe. This is caused by its anti-estuarine circulation. It is also the largest body of water in the world which is unequivocally phosphorus limited with a nitrate:phosphate ratio of 28:1 far in excess of the Redfield ratio of 16:1. It is P starved with high N:P ratios for DOM and POM.
We have recently been able to explain why the basin is P limited. There is an excess of N over P in the nutrient supply, particularly the atmospheric supply. However, unlike other bodies of water where the N:P input is greater than 16:1, in the Eastern Mediterranean there is very limited denitrification and thus no biological process available to reduce the N:P ratio to Redfieldian numbers. This is because of the low primary productivity in the system. Thus we have been able to show that the two unusual features of the Eastern Mediterranean are connect. N fixation is an unimportant process in this system.
I was coordinator of the EU-CYCLOPS project, which was the first Lagrangian nutrient addition experiment that did not involve iron. We showed that the Eastern Mediterranean is phosphorus starved with no nutrient reservoir (DOM, POM, surface or deep water) having adequate amounts of P. In winter the system is P limited in the conventional sense. By contrast in summer when the Lagrangian experiment was carried out, to our surprise when phosphate fertilizer was added the chlorophyll content in the surface water decreased. We explained this observation by noting that surface water was P limited for bacteria for the entire year because they had access to the large DON reservoir but N & P co-limited for phytoplankton in summer. After phosphate was added both bacteria and phytoplankton were grazed. We showed that there was also a considerable excess of grazing potential, which resulted in a new process called trophic tunnelling which transferred primary productivity rapidly to zooplankton grazers.
 SEM picture of Fe nanoparticles found in Western Mediterranean Saharan dust |
I have been involved in long term sampling of atmospheric inputs into the eastern Mediterranean including dust and carried out studies to quantify it importance to biogeochemical processes in the basin.
Mineral dust and aerosols are important sources of iron and phosphorus particularly to the open ocean where they are frequently the major source. In the atmosphere such particles often form cloud condensation nuclei and sites where acid gases condense. As cloud water evaporates the pH of the water film descreases. As a result such particles can often be subject to highly acid conditions in the atmosphere especially in areas where there is atmospheric pollution.
We have carried out detailed studies which have shown that iron dissolves under such acid conditions and when the pH becomes neutralized in clouds, chemically reactive Fe nanoparticles form. The potential for such reactive Fe to form is controlled by the amount and nature of chemical weathering in the source area as well as acid processes in the atmosphere. Our studies have found that the rate at which Fe is produced can be described most accurately by a three phase model. Our data is being used to calibrate more accurately global climate and cloud models.
We have also shown that similar processes cause P to be converted from relatively insoluble apatite and Fe-bound P to labile P available directly for phytoplankton uptake. This process is particulrly important in the Eastern Mediterranean where mineral dust from the Sahara meets polluted air-masses for southern Europe.
 87Sr/86Sr isotopic ratios in sediment provide evidence for reduction of rainfall in the Nile catchment compatible with the theory that a prolonged drought caused the collapse of the Old Kingdom in Egypt. |
We have carried out studies to look at climate change in Africa over the past 25,000 years. Using 87Sr/ 86Sr we have examined the paleoclimate record of the Nile flood and Saharan dust in two sediment locations in the eastern Mediterranean. We have found that between 12ka BP and 4.2ka BP, there was a systematic increase in Nile water flow at the same time as a systematic decrease in the supply of both Blue Nile sediment and Saharan dust to the Mediterranean. This was caused by a increase in the intensity of the African monsoon which caused a ‘greening’ of the Sahara desert. At the end of this period there was a rapid decrease in rainfall which reached its climax with a long period of drought which caused the end of the Old Kingdom in Egypt.
 Loch Duich has been used as the field site to study sources of anthropogenic trace metals and other sedimentary geochemical processes. |
We have a major interest in understanding natural processes in recent sediments and in using sediments as a historical record of past environmental change.
We have long known that athropogenic trace metals have been deposited in the sediment of Loch Duich since the beginning of the Industrial revolution. , We have shown that almost all of the Copper and Zinc was transported with particles from the Irish Sea while 50% of the lead was derived from atmosperic input.
Mariculture is the last untapped food resource on earth. We have been involved in developing intensive mariculture systems that are both commercially viable and environmentally friendly. Recently a fishpond-seaweed-abalone system developed from our work was put into commercial operation in Israel .
A new system which works entirely on bacterial biofilters has been developed. Fish excrete ammonia which is toxic to the fish. This ammonia is oxidised to nitrate in a nitrification filter and then converted to nitrogen gas in an anaerobic denitrifying filter. This system, has operated successfully for several years. It runs without any exchange of water thus enabling mariculture to be carried far from the sea if necessary. It is now in commercial operation in Hudson, New York. Future research work will involve examining the dynamics of P cycling within this system.Krom, M.D., Emeis K-C, van-Cappellan, P. (2010) Why is the Eastern Mediterranean P limited? Progress in Oceanography. Vol 85; p236-244.
Shi, Z., Krom, M.D., Bonneville, S., Baker, A.R., Jickells, T.D., and Benning, L.G., (2009) Formation of iron nanoparticles and increase in iron reactivity in mineral dust during simulated cloud processing. Environ. Sci. Technology 43, 6592-6596.
Thingstad, T.F., Krom, M.D., Mantoura, R.F.C., Flaten, G.A.F., Groom, S., Herut, B., Kress, N., Law, C., Pasternak, A., Pitta, P., Psarra, S., Rassoulzadegan, F., Tanaka, T., Tselipides, A., Wassmann, P., Woodward, E.M.S., Wexels Riser, C., Zodiatis, G., Zohary, T., 2005. Nature of P limitation in the ultra-oligotrophic Eastern Mediterranean, Science 309, 1068-1071
Palmer-Felgate, EJ; Mortimer, RJG; Krom, MD, and Jarvie, H.P. (2010) Impact of Point-Source pollution on Phosphorus and Nitrogen Cycling in Stream-bed sediments. Env. Sci. & Technology 44 (3) 908-914.
Krom, M.D., Emeis K-C, van-Cappellan, P. (2010) Why is the Eastern Mediterranean P limited? Progress in Oceanography. Vol 85; p236-244.
Tanaka, T., Zohary, T., Krom, M.D., Law, C.S., Pitta, P., Psarra, S., Rassoulzadegan, F, Thingstad, F., Tselipides, A, Woodward, M.S., Fonnes-Flaten, G.A., Skjoldal., E.F., Zodiatis, G. (2007) Microbial community structure and function in the Levantine basin of the eastern Mediterranean. Deep-Sea Research I. 1721-1743
Thingstad, T.F., Krom, M.D., Mantoura, R.F.C., Flaten, G.A.F., Groom, S., Herut, B., Kress, N., Law, C., Pasternak, A., Pitta, P., Psarra, S., Rassoulzadegan, F., Tanaka, T., Tselipides, A., Wassmann, P., Woodward, E.M.S., Wexels Riser, C., Zodiatis, G., Zohary, T., 2005. Nature of P limitation in the ultra-oligotrophic Eastern Mediterranean, Science 309, 1068-1071
Krom, M.D., Wassman, P. and Zohary, T. 2005. On the nature of phosphorus cycling and limitation in the Eastern Mediterranean. Deep-Sea Research II, Volume 52: Nos 22-23
Carbo, P., Krom, M.D., Homoky, W.B., Benning, L.G., Herut, B., 2005. Impact of atmospheric deposition on N and P geochemistry in the southeastern Levantine basin. Deep-Sea Research II Volume 52: Nos 22-23, 3041-3053.
Flaten, G.A.F., Skjoldal, E.F., Krom, M.D., Law, C.S., Mantoura, R.F.C., Pitta, P., Psarra, S., Tanaka, T., Tselepides, A., Woodward, E.M.S., Zohary, T., Thingstad, T.F., 2005. Studies of the microbial P-cycle during a Lagrangian phosphate-addition experiment in the Eastern Mediterranean. Deep-Sea Research II Volume 52: Nos 22-23 2928-2943
Groom, S., Herut, B., Brenner, S., Zodiatis, G., Psarra, S., Kress, N., Krom, M.D., Law, C.S., Drakopoulos, P., 2005. Satellite derived spatial and temporal biological variability in the Cyprus Eddy. Deep-Sea Research II Volume 52: Nos 22-23 2990-3010
Herut, B., Zohary, T., Krom, M.D., Mantoura, R.F.C., Pitta, P., Psarra, S., Rassoulzadegan, F., Tanaka, T., Thingstad, F., 2005. Response of East Mediterranean surface water to Sahara dust: On-board microcosm experiment and field observations. Deep-Sea Research II Volume 52: Nos 22-23 3024-3040
Krom, M.D., Thingstad, T.F., Carbo, P., Drakopoulos, P., Fileman, T.W., Flaten, G.A.F., Groom., S., Herut, B., Kitidis, V., Kress, N., Law., C.S., Liddicoat, M.I., Mantoura, R.F.C., Pasternak, A., Pitta, P., Polychronaki, T., Psarra, S., Rassoulzadegan, F., Skjoldal, E.F., Spyres, G., Tanaka, T., Tselepides, A., Wassmann, P., Wexels-Riser, C., Woodward., E.M.S., Zodiatis, G., Zohary, T., 2005. The CYCLOPS P addition Lagrangian experiment in the Eastern Mediterranean. Deep-Sea Research II Volume 52: Nos 22-23 3090-
Krom, M.D., Woodward, E.M.S., Herut, B., Kress, N., Carbo, P., Mantoura, R.F.C., Spyres, G., Thingstad, T.F., Wassmann, P., Wexels Riser, C., Kitidis, V., Law, C.S., Zodiatis, G., 2005. Nutrient cycling in the south east Levantine basin of the Eastern Mediterranean: results from a phosphorus starved system. Deep-Sea Research II Volume 52: Nos 22-23 2879-2896
Psarra, S., Zohary, T., Krom, M.D., Mantoura, R.F.C., Polychronaki, T., Stambler, N., Tanaka, T., Tselepides, A., Thingstad, T.F., 2005. Phytoplankton response to a Lagrangian phosphate addition in the Levantine Sea (Eastern Mediterranean). Deep-Sea Research II Volume 52: Nos 22-23 2944-2960.
Zohary, T., Herut, B., Krom, M.D., Mantoura, R.F.C., Pitta, P., Psarra, S., Rassoulzadegan, F., Stambler, N., Tanaka, T., Thingstad, T.F., Woodward, E.M.S., 2005. P-limited bacteria but N&P co-limited phytoplankton in the Eastern Mediterranean – a microcosm experiment. Deep-Sea Research II, Volume 52: Nos 22-23 3011-3023
Krom, M.D., Herut, B., Mantoura, R.F.C. (2004) Nutrient budget for the eastern Mediterranean: Implications for P limitation. Limnology and Oceanography 49: 1582-1592.
Krom, M.D., Herut, B. and Mantoura, R.F.C. (2004) Nutrient budget for the Eastern Mediterranean : Implications for P limitation. Limnology and Oceanography. 49: 1582-1592.
Krom, M.D., Groom, S., Zohary, T., (2003) The Eastern Mediterranean in The Biogeochemistry of Marine Systems ( Eds K.D.Black and G.B.Shimmield) ., Blackwell Publishing, Oxford., 91-122
Pan, G., Krom, M.D., and Herut, B., (2002) Adsorption- desorption of phosphate onto/from airborne dust and riverborne particulates in East Mediterranean seawater. Environmental Science and Technology, 36 (16), 3519-3524.
L.M.Eijsink , M.D.Krom and B.Herut, (2000) Speciation and burial flux of phosphorus in the surface sediments of the eastern Mediterranean . American Journal of Science, 300 (6), 483-503
Krom, M.D., Cliff, R.A., Eijsink, L.M., Herut, B., Chester , R .(1999) The characterisation of Saharan dusts and Nile Particulate matter in sediments from the Levantine basin using Sr isotopes. Marine Geology 155: 319-330.
Krom, M.D., Michard, A., Cliff, R.A. and Strohle, K. (1999) Sources of sediment to the Ionian Sea and western Levantine basin of the Eastern Mediterranean during S-1 sapropel times. Marine Geology 160, 45-61.
Krom, M.D., Brenner, S., Kress, N., Neori, A., and Gordon, L.I. (1992). Nutrient dynamics and New Production in a Warm-core eddy from the E.Mediterranean. Deep-Sea Research. 39 (3/4):467-480
Krom, M.D., Brenner, S., Kress, N., Neori, A., and Gordon, L.I. (1993). Nutrient distributions during an annual cycle across a warm-core oceanic eddy from the E.Mediterranean sea. Deep Sea Research . 40 (4): 805-825
Krom, M.D., Brenner, S., Kress, N. and Gordon, L.I. (1991) Phosphorus limitation of Primary Productivity in the E.Mediterranean sea. Limnol . Ocean. 36 (3): 424-432.
Shi, Z., Krom, M.D., Bonneville, S., Baker, A.R., Jickells, T.D., and Benning, L.G., (2009) Formation of iron nanoparticles and increase in iron reactivity in mineral dust during simulated cloud processing. Environ. Sci. Technology 43, 6592-6596.
Mara. P., Mihalopoulos, N., Gogou, A., Daehnke, K., Schlarbaum, T., Emeis, K.-C., Krom, M.D. (2009) Isotopic composition of nitrate in wet and dry atmospheric deposition on Crete/ Eastern Mediterranean Sea. Global Biogeochemical Cycles. 23, GB4002, doi:10.1029/2008GB003395.
B.Herut , R.Collier and M.D.Krom (2002) The role of dust in supplying nitrogen and phosphorus to the South East Mediterranean. Limnology and Oceanography, 47(3), 870-878.
Herut , B., Nimmo, M., Medway, A., Chester , R., and Krom, M.D. (2001) Dry atmospheric inputs of trace metals at the Mediterranean coast of Israel (SE Mediterranean): Sources and Fluxes. Atmospheric Environment. 35/4 803-813.
Herut , B., Krom, M.D., Pan, G. and Mortimer, R. (1999) Atmospheric input of nitrogen and phosphorus to the SE Mediterranean: sources, fluxes and possible impact. Limnology & Oceanography. 44(7), 1683-1692
Stanley, J-D., Krom, M.D., Cliff, R.A. and Woodward, J.C. (2003) Nile flow failure at the End of the Old Kingdom, Egypt: Strontium isotopic and Petrologic evidence. Geoarcheology Vol. 18, No. 3 395-402.
M.D.Krom , J.- D.Stanley, R.A.Cliff and J.C.Woodward (2002). River Nile sediment fluctuations over the past 7000 years and their key role in sapropel development. Geology 30 (1) 71-74.
Struck, U., Emies, K-C., Voss, M., Krom, M.D., and Rau, G.H., (2001) Biological productivity during Sapropel S5 formation in the eastern Mediterranean Sea – Evidence from Stable Isotopes of Nitrogen and Carbon. Geochimica Cosmochimica Acta 65: 3249-3266
Palmer-Felgate, EJ; Mortimer, RJG; Krom, MD, and Jarvie, H.P. (2010) Impact of Point-Source pollution on Phosphorus and Nitrogen Cycling in Stream-bed sediments. Env. Sci. & Technology 44 (3) 908-914.
Palmer-Felgate, E.J., Jarvie, H.P., Withers, P.J.A., Mortimer, R.J.C., Krom, M.D. (2009), Stream-bed phosphorus in paired catchments with different agricultural land use intensity. Agriculture, Ecosystems and Environment. Volume: 134 (1-2) : 53-66
Krom, M.D, Carbo, P. , Clerici, S., Cundy, A. and Davies, I.M. (2009) Sources and timing of trace metal contamination to sediments in sealochs, N.W.Scotland, Estuarine and Coastal shelf Science Vol 83(2), 239-251.
Bottrell, S.H., Mortimer, R.J.G., Davies, I.M., Harvey, S.M., and Krom, M.D., (2009) Sulphur cycling in organic-rich marine sediments from a Scottish fjord. Sedimentology 56(4) 1159-1173.
S.H.Bottrell, R.J.G.Mortimer, M.Spence, M.D.Krom., J.M.Clark, and P.J.Chapman. (2007) Insights into redox cycling of sulphur and iron in peatlands for high-resolution gel probe sampling. Chemical Geology 244, 409-420.
Poulton, S.W., Krom, M.D. and Raiswell, R. (2004) A revised scheme for the reactivity of iron oxyhydr(oxide) minerals towards dissolved sulphide. Geochimica Cosmochimica Acta 68: 3703-3715.
Mortimer, R.J.G., Harris, S.J., Krom, M.D., Freitag, T., Prosser, J., Barnes, J., Anschultz, P., Hayes, P., and Davies I.M. (2004) Anoxic nitrification in marine sediments Marine Ecology Progress Series 276: 37-51.
Mortimer, R.J.G., Harris, S.J., Krom, M.D., Freitag, T., Prosser, J., Barnes, J., Anschultz, P., Hayes, P., and Davies I.M. (2004) Anoxic nitritication in marine sediments Marine Ecology Progress Series 276: 37-51.
R.J.G.Mortimer , M.D.Krom, W.Davison, H.Zhang, P.J.Hayes & I.M.Davies. (2002) Evidence for suboxic nitrification in recent marine sediments. Marine Ecology Progress Series, Vol 236: 31-35.
Krom, M.D., Mortimer, R.J.G., Poulton, S.W., Hayes, P., Davies, I.M., Davison W. and Zhang, H. (2002) In-situ determination of dissolved iron production in recent marine sediments Aquatic Science, 64 282-291.
Nishri , A., Stiller, M., Rimmer, A., Geifman, Y., and Krom M.D., (1999 ) Lake Kinneret (The Sea of Galilee): the effects of diversion of external salinity sources and the probable chemical composition of the internal salinity sources. Chemical Geology 158, 37-52.
Mortimer, R.J.G., Krom M.D., Watson, P.G., Frickers, P.E., Davey, J.T., & Clifton R.J. (1999) Sediment-water exchange of nutrients in the intertidal zone of the Humber Estuary. Marine Pollution Bulletin 37: 259-277
Mortimer, R.J.G., Krom, M.D., Boyle, D.R., Nishri, A. (1999) Use of a high resolution pore water gel profilers to measure groundwater fluxes at an underwater saline seepage site in Lake Kinneret , Israel . Limnology & Oceanography, 44(7) 1802-1809.
Mortimer, R., Krom, M.D., Hall, P.O.J., Hulth, S. and H.Stahl, (1998). Use of gel probes for the determination of high resolution solute distributions in marine and estuarine pore waters. Marine Chemistry. 63, 119-129
van Santvoort, P.J.M., de Lange, G.J., Thomson, J., Cussen, H., Wilson , T.R.S., Krom, M.D., and Strohle, K. (1996). Active post-depositional oxidation of the most recent sapropel (S1) in sediments of the Eastern Mediterranean . Geochim . Cosmochim . Acta . Vol. 60 No: 21 4007-4024.
Krom, M.D., Hornung, H., and Kaufman, A. (1994) Industrial mercury in combination with natural Pb 210 as time dependant tracers of sedimentation and mercury removal from Haifa bay, Israel . Estuarine Coastal and Shelf Science. 38, 625-642.
Kress, N.,, Golik, A., Galil, B., Krom, M.D. (1993). Monitoring the disposal of Coal Fly Ash at a deep water disposal site in the Eastern Mediterranean sea . Marine Pollution Bulletin. 26(8), 447-456.
Krom, M.D., Hornung, H. and Cohen, Y. (1990) Determination of the Environmental Capacity of Haifa Bay with respect to Mercury. Marine Pollution Bulletin 27 (7): 349-354.
Krom M.D. and Berner R.A., (1981). The diagenesis of phosphorus in a nearshore marine sediment. Geochim . Cosmochim . Acta 45: 207-216.
Krom, M.D. and Berner, R.A. (1980). Adsorbtion of phosphate in anoxic marine sediments. Limnol . Oceanogr . 25(4): 797-806.
Krom, M.D. and Berner, R.A. (1980) The diffusion coefficients of sulphate, ammonium and phosphate in anoxic marine sediments. Limnol . Oceanogr . 25(2): 327-337.
Neori, A., Krom, M.D., van Rijn, J. (2007) Biogeochemical processes in intensive zero-effluent marine fish culture system with recirculating aerobic and anaerobic biofilters Journal of Experimental Marine Biology and Ecology, 349 235-247.
Karakassis, I., Pitta, P., and Krom M.D. (2005) Contribution of fish farming to the nutrient loading of the Mediterranean. Scientia Marina 69 (2). 313-321.
Gelfand, I, Barak, Y, Even-Chen, Z., Cytryn, E., van Rijn, J., Krom, M.D., Neori, A. (2003) A novel zero discharge intensive Seawater recirculating system for the culture of marine fishJ.of the World Aquaculture Society. 34: (3) , 344-358.
Y.Barak , E.Cytryn, I. Gelfand, M.Krom and J. van Rijn (2003) Phosphate removal in a marine prototype recirculating aquaculture system. Aquaculture, 220 313-326
M.D.Krom , A.Neori, J.van Rijn, S.W.Poulton and I.M.Davies (2001) Environmentally friendly marine agriculture. Ocean Challenge Vol 10 (2), 22-27.
Neori , A., Krom, M.D., Ellner, S.E., Boyd, C.E., Popper, D., Rabinovitch, R., Davison, P.J., Dvir, O., Zuber, D., Ucko, M., Angel, D., Gordin, H. (1996). Seaweed biofilters as regulators of water quality in integrated fish-seaweed culture units. Aquaculture. 141: (3-4), 183-199.
Krom, M.D., Ellner, S., van Rijn, J. and Neori, A. (1995). Nitrogen and phosphorus cycling and transformations in a prototype "non-polluting" integrated mariculture system, Eilat , Israel . Marine Ecol. Progress Series. 118: 25-36.
Neori , A., Krom M.D., Cohen, I. , and Gordin, H. (1989). Water quality conditions and particulate chlorophyll a of new intensive seawater fishponds in Eilat , Israel : daily and diel variations. Aquaculture. 80: 63-78.
Krom, M.D. and Neori, A. (1989). A total Nutrient budget for an experimental intensive fishpond with circularly moving seawater. Aquaculture. 83, 345-358.
Krom, M.D., Porter, C., and Gordin, H. (1985b) . Description of the water quality conditions in a semi-intensively cultured marine fish pond in Eilat , Israel . Aquaculture 49: 141-157.