Some physical,chemical, and microbiological characteristics of two beaches of anglesey

Observations during 1971 and 1972 of some of the physical, chemical, and microbiological characteristics of contrasting Anglesey beaches, Newborough and Llanddona, are reported. The fine sandy beach at Newborough was observed to be very unstable and topographical changes were recorded. In particular, the movement of a sand wave across the intertidal zone from low water to extinction at the foot of the dune system was observed. The more extensive fine sandy beach at Llanddona had greater stability.Chemically, each beach was variable both spatially and temporally, with ill-defined patterns of concentration changes. Sand from Newborough beach was low in organic carbon (0.07–0.40 mg C/g dry sand) and well aerated, and the soluble inorganic nitrogen in the ground water (up to 30 μg-at. N/l) was dominated by nitrate form (up to 22 μg NO₃-N/l). By contrast, Llanddona sand had a more variable organic carbon content (0.22–2.25 mg C/g dry sand), was wetter, and poorly aerated with consequent sulphide lenses; its dissolved inorganic nitrogen (over 70 μg-at. N/l) was completely dominated by the ammonium form.Microbiologically, the beaches possessed dissimilar bacterial floras, and sediment from Llanddona gave higher bacterial counts than that from Newborough. For both beaches it is shown that estimated bacterial numbers decreased with depth as well as down the intertidal zone.