Arid regions worldwide, for example, Sudan, are affected by climate change and susceptible to environmental deterioration. In this study, temperature and rainfall data from 1985 to 2015 obtained from the Sudan Meteorological Authority were compared with satellite images of vegetation coverage in southern Port Sudan. The objective of this study was to determine the impact of climate change on the vegetation cover in this area. Results showed significant increases in the annual maximum, minimum and average temperatures with time, and precipitation showed a slight but not significant decrease from 1985 to 2015. The rates of increase for the annual maximum, minimum and average temperatures were 0.08 °C/year, 0.03 °C/year and 0.06 °C/year, respectively, and precipitation decreased at a rate of 0.12 mm/year. Higher shrub abundance and greater water area in 2013, 1995 and 1990 were probably due to high rainfall in the years preceding these years. Decreased shrub abundance in the year 2000 could be due to the significantly higher temperatures after 1998. There was no decreasing trend in shrub coverage from 1985 to 2015, but the overall increase in temperature and decrease in precipitation from 1985 to 2015 indicate a potential threat to vegetation in this area in the future.

Sedimentary phosphorus (P) forms are important representatives of P sources and their bioavailability as well as the potential of sediments to release P in water. In this study, surface sediments along a transect of the Changjiang Estuary and two transects along the Andong salt marsh in the southwest of Hangzhou Bay were subjected to the elucidation of sedimentary P species using the standards, measurements, and testing (SMT) and sequential extraction (SEDEX) methods. The results showed that the mean sedimentary P forms elucidated by the SMT method were as follows: organic P (OP; ∼11–14 mg/kg; ∼30–45% of total P; TP) > apatite P (∼5–15 mg/kg; ∼21–36% TP) > Fe/Al-P (∼8–14 mg/kg; ∼31–34% TP), with inorganic P (IP) composing 54–70% of TP. The mean sedimentary P forms elucidated by the SEDEX method were as follows: authigenic P (∼54–68 mg/kg; ∼41–46% TP) > extractable P (Ex-P; ∼36–53 mg/kg; ∼28–34%) > Fe-P (∼21–27 mg/kg; ∼13–19%) > OP (∼8.7–13 mg/kg; ∼5–8%) > detrital P (De-P; ∼2 mg/kg; ∼1–2% TP), with IP composed of ∼91–94% TP. These results showed that the SEDEX method elucidated higher concentrations of sedimentary P forms as well as the TP from these coastal sediments although the SMT method had the advantage of being more economic and faster. The results of both the SMT and SEDEX methods showed that the Andong salt marsh and Changjiang Estuary sediments had much bioavailable P. The mean percentages of bioavailable P from the SMT and SEDEX methods were ∼64–74% and 52–56% of TP, respectively, indicating that these sediments were prone to release P to the coastal areas.