Atmospheric deposition of nutrients, particularly nitrogen and phosphorus has the capacity to significantly affect the productivity and biogeochemistry of aquatic ecosystems. The objective of this study was to assess ...Atmospheric deposition of nutrients, particularly nitrogen and phosphorus has the capacity to significantly affect the productivity and biogeochemistry of aquatic ecosystems. The objective of this study was to assess the impact of land use/cover types on the atmospheric deposition of nutrients around Lake Kivu. Dry and wet atmospheric deposition samples were collected from four different land use/cover types (forest, wetland, agricultural and urbanized area) at four stations (Goma, Lwiro, Bukavu and Iko) around the Lake Kivu basin. The highest annual loading of dry total phosphorus (TP) was recorded at a station located in an urban area at Goma (4.4 ± 3.9 μmol/m<sup>2</sup>/yr) and the highest dry deposition of total nitrogen (TN) was recorded at Iko (84.5 ± 41.2 μmol/m<sup>2</sup>/yr). High wet TP and TN were at Bukavu (0.7 ± 1.1 μmol/m<sup>2</sup>/yr) and Iko (21.7 ± 34.7 μmol/m<sup>2</sup>/yr) respectively. High dry TP loads were recorded in the forest area of Goma and the highest dry TN at Lwiro. High wet TP loads were record in agriculture at Goma and high values of wet TN in agriculture at Iko. Phosphorus and nitrogen deposition rates around Lake Kivu were similar to those reported for other African lakes. The highest rate of TP was recorded mainly in the forest area for dry deposition while high TN was recorded in all types of land use/cover in the basin. This study found out that forest traps high concentration of nutrient than other land uses/covers.展开更多
A study concerning the throughfall and stemflow chemistry in the Castanopsis eyrei forest was conducted during 1993—1994. The results showed that the net throughfall nutrient fluxes showed consistent canopy effec...A study concerning the throughfall and stemflow chemistry in the Castanopsis eyrei forest was conducted during 1993—1994. The results showed that the net throughfall nutrient fluxes showed consistent canopy effects on precipitation chemistry. In general, potassium, calcium, magnesium, sodium and sulphur were added to precipitation by foliage, whereas the canopy absorbed nitrogen and phosphorus from precipitation. In stemflow, negative net deposition occurred for phosphorus only, and the rest nutrients were added to precipitation by tree stems and branches. The total net depositions of nutrients in both throughfall and stemflow followed the sequence of potassium>calcium>sodium>magnesium>sulphur, ranging between 2 56—52 54 kg/(hm 2·a). For potassium and calcium, net throughfall was the largest pathway, and the net throughfall contribution to the total yearly nutrient return to the forest soil was 54% and 42% respectively. Although the net stemflow contribution to the total yearly nutrient return was small (between 0 and 13%), stemflow represented the largest pathway of water and nutrient input to the stemflow zone of the forest floor in the C.eyrei forest ecosystem.展开更多
文摘Atmospheric deposition of nutrients, particularly nitrogen and phosphorus has the capacity to significantly affect the productivity and biogeochemistry of aquatic ecosystems. The objective of this study was to assess the impact of land use/cover types on the atmospheric deposition of nutrients around Lake Kivu. Dry and wet atmospheric deposition samples were collected from four different land use/cover types (forest, wetland, agricultural and urbanized area) at four stations (Goma, Lwiro, Bukavu and Iko) around the Lake Kivu basin. The highest annual loading of dry total phosphorus (TP) was recorded at a station located in an urban area at Goma (4.4 ± 3.9 μmol/m<sup>2</sup>/yr) and the highest dry deposition of total nitrogen (TN) was recorded at Iko (84.5 ± 41.2 μmol/m<sup>2</sup>/yr). High wet TP and TN were at Bukavu (0.7 ± 1.1 μmol/m<sup>2</sup>/yr) and Iko (21.7 ± 34.7 μmol/m<sup>2</sup>/yr) respectively. High dry TP loads were recorded in the forest area of Goma and the highest dry TN at Lwiro. High wet TP loads were record in agriculture at Goma and high values of wet TN in agriculture at Iko. Phosphorus and nitrogen deposition rates around Lake Kivu were similar to those reported for other African lakes. The highest rate of TP was recorded mainly in the forest area for dry deposition while high TN was recorded in all types of land use/cover in the basin. This study found out that forest traps high concentration of nutrient than other land uses/covers.
文摘A study concerning the throughfall and stemflow chemistry in the Castanopsis eyrei forest was conducted during 1993—1994. The results showed that the net throughfall nutrient fluxes showed consistent canopy effects on precipitation chemistry. In general, potassium, calcium, magnesium, sodium and sulphur were added to precipitation by foliage, whereas the canopy absorbed nitrogen and phosphorus from precipitation. In stemflow, negative net deposition occurred for phosphorus only, and the rest nutrients were added to precipitation by tree stems and branches. The total net depositions of nutrients in both throughfall and stemflow followed the sequence of potassium>calcium>sodium>magnesium>sulphur, ranging between 2 56—52 54 kg/(hm 2·a). For potassium and calcium, net throughfall was the largest pathway, and the net throughfall contribution to the total yearly nutrient return to the forest soil was 54% and 42% respectively. Although the net stemflow contribution to the total yearly nutrient return was small (between 0 and 13%), stemflow represented the largest pathway of water and nutrient input to the stemflow zone of the forest floor in the C.eyrei forest ecosystem.
