Christopher Gordon

This study compared ecological health between Msimbazi, a highly urbanized mangrove in Dar es Salaam, and Ras Dege, a relatively undeveloped peri-urban site. In September 2023, water, sediment, and Uca inversa crabs were sampled across six stations per site to assess microbial quality, nutrient enrichment, heavy metals, and macrofauna diversity. Msimbazi exhibited extreme microbial contamination, with faecal coliform, total coliform, and enterococci levels over 800% higher than Ras Dege (p<0.01). Nitrate concentrations reached 10.28 ± 1.00 mg/L in Msimbazi versus 0.55 ± 0.08 mg/L at Ras Dege (p<0.001). Heavy metals (Cr, Cd, Pb, Ni, Cu, Zn) were consistently elevated in Msimbazi water and sediment; sediment Cd (3.34 ± 0.60 mg/kg) exceeded the Western Indian Ocean guideline (0.68 mg/kg). Crab tissues from both sites exceeded FAO limits for Cr, Cd, and Pb, with Msimbazi crabs containing up to nine times the Pb limit. Macrofauna diversity was lower at Msimbazi (H′ = 0.63; 3 species) compared to Ras Dege (H′ = 2.18; 18 species), reflecting ecological imbalance. K-dominance curves indicated extreme dominance by a few tolerant species at Msimbazi, versus more even communities at Ras Dege. Across all indicators, Msimbazi is classified as severely degraded, with nutrient loading, heavy metal accumulation, microbial proliferation, faunal simplification, and food safety risks. Ras Dege, though healthier, shows early contamination signs. These findings highlight the urgent need for wastewater management, stricter discharge controls, and conservation measures to safeguard urban and peri-urban mangrove ecosystems.

This study assessed the concentrations and health risks of heavy metals in cabbage (Brassica oleracea) and lettuce (Lactuca sativa) cultivated across three urban land surface temperatures in the Greater Accra Metropolitan Area (GAMA): Atomic (low land surface temperature, LST), Ashaiman (moderate LST), and Korle-Bu (high LST). The objective was to assess the influence of urban land surface temperature on heavy metal accumulation and associated human health risks. Results revealed that arsenic (As) and mercury (Hg) levels were consistently low (≤0.002 mg/kg) and remained below the maximum residue limits (MRLs) at all sites. However, cadmium (Cd), lead (Pb), and nickel (Ni) concentrations exceeded MRLs in both vegetables. Cd ranged from 1.40 ± 0.27 mg/kg (lettuce, Ashaiman) to 3.13 ± 0.99 mg/kg (cabbage, Atomic), while Pb varied between 0.90 ± 0.84 mg/kg (lettuce) and 2.62 ± 1.22 mg/kg (cabbage). Ni concentrations exceeded the permissible limit (0.2 mg/kg) across all LST zones, with the highest at Korle-Bu (0.65 ± 0.07 mg/kg). Cumulative heavy metal concentrations increased significantly (p < 0.005) with rising LST, particularly in cabbage. Noncarcinogenic risk assessment indicated that Cd and Ni were the dominant contributors to human health risk, with target hazard quotients (THQ) and hazard indices (HI) exceeding the safety threshold (HI > 1) for both adults and children, especially in Atomic and Korle-Bu. Children were more vulnerable, exhibiting higher exposure levels. Carcinogenic risk (CR) analysis further identified As, Cd, and Ni as the main carcinogens, with total cancer risk (TCR) values across all sites and age groups exceeding the USEPA acceptable range (1 × 10⁻⁶–1 × 10⁻⁴). The findings suggest that increasing urban temperatures exacerbate heavy metal accumulation in leafy vegetables, posing significant noncarcinogenic and carcinogenic health risks, particularly to children.

This study investigates the effect of high urban land temperatures on pesticide residue (PR) accumulation in cabbage and lettuce and on public health in the Greater Accra Metropolitan Area (GAMA) in Ghana. A comparative toxicological analysis regarding the food system was conducted with 66 farmers across three land surface temperatures: low (Atomic, n = 22), moderate (Ashaiman, n = 22), and high (Korle-Bu, n = 22). Pesticide residue concentrations were assessed using an ANOVA to examine spatial variations across sites. The results indicate a strong correlation between high land surface temperatures and pesticide residue accumulation, with lettuce recording significantly (p < 0.05) higher PR levels than cabbage. Several pesticides, including carbendazim (CBZ), Imidacloprid (IMI), Thiamethoxam (TMX), and Chlorpyrifos (CHL), exceeded the maximum residue limits (MRLs) set by the World Health Organization (WHO) and the European Union (EU) at moderate and high-temperature sites. carbendazim was the dominant pesticide detected, with a concentration of 19.0 mg/kg in lettuce, which far exceeded its maximum residue limit (MRL) of 0.10 mg/kg across all study sites. Statistical analyses (PERMANOVA) confirmed that land surface temperatures and pesticide types significantly influenced the PR concentrations. Public health risk assessments indicate that children are more vulnerable to pesticide exposure than adults. The toxicity hazard quotient (THQ) for organophosphate pesticides, particularly CHL and Dimethoate (DMT), exceeded safe thresholds at moderate and high-temperature sites.

The Sustainable Development Goals aim to improve access to resources and services, reduce environmental degradation, eradicate poverty and reduce inequality. However, the magnitude of the environmental burden that would arise from meeting the needs of the poorest is under debate—especially when compared to much larger burdens from the rich. We show that the ‘Great Acceleration’ of human impacts was characterized by a ‘Great Inequality’ in using and damaging the environment. We then operationalize ‘just access’ to minimum energy, water, food and infrastructure. We show that achieving just access in 2018, with existing inequalities, technologies and behaviours, would have produced 2–26% additional impacts on the Earth’s natural systems of climate, water, land and nutrients—thus further crossing planetary boundaries. These hypothetical impacts, caused by about a third of humanity, equalled those caused by the wealthiest 1–4%. Technological and behavioural changes thus far, while important, did not deliver just access within a stable Earth system. Achieving these goals therefore calls for a radical redistribution of resources.

Climate-smart agriculture (CSA) is an approach that helps guide actions to transform agri-food systems towards green and climate-resilient practices and it remains prominent in food systems transformation in the light of increasing climate change impacts. Unfortunately, the quantification of the greenhouse gas (GHG) mitigation potential of CSA approaches is currently limited. Using the Cool Farm Tool (CFT), this paper quantifies the GHG mitigation of CSA based on farm-level experimental data. Individual interviews and focus group discussions were also conducted to identify farmers’ choices and willingness to adopt CSA practices. The study compared the GHG emission mitigation of CSA practices for two scenarios (baseline and mitigation). The study found that organic fertilizer input, residue incorporation, no-inorganic fertilizer and no-pesticide input reduced GHG emission intensity of sorghum (to 93.2 ± 25 kg CO₂e GHG kg^− 1 sorghum), rice (79.2 ± 22 kg CO₂e GHG kg^− 1 rice) and groundnut (69.7 ± 20 kg CO₂e GHG kg^− 1 groundnut) compared to the baseline. Lower GHG emission intensity was achieved with higher crop yield under CSA interventions. The study recommends that CSA promoters such as the Consultative Group for International Agriculture Research (CGIAR), Food and Agriculture Organization (FAO) and the World Bank focus on crop-specific CSA practices for higher GHG mitigation. CSA promoters such as the CGIAR, FAO and the World Bank should embrace participatory processes such as farmer schools to increase CSA uptake.

Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation.

Semi-Arid Regions (SARs) of West Africa are considered climate change “hotspots” where strong ecological, economic and social impacts converge to make socio-ecological systems particularly vulnerable. While both climatic and non-climatic drivers interact across scales to influence vulnerability, traditionally, this inter-connectedness has received little attention in vulnerability assessments in the region. This study adopted the vulnerability patterns framework, operationalized using the Multidimensional Livelihood Vulnerability approach to include both climatic and non-climatic stressors to analyze differential household vulnerability in SARs of Mali. Findings showed that while drought was the most mentioned climate-related stressor, households were also exposed to a diversity of environmental and socio-economic stressors, including food scarcity, livestock disease, labour unavailability, crop damage, and erratic rainfall patterns. The typology revealed three vulnerability archetypes differentiated by adaptive capacity and sensitivity. Availability of productive household members, household resource endowments, livelihood diversification and social networks were the main discriminant factors of household adaptive capacity, while challenges relating to food and water security make households more sensitive to stressors. The analysis highlighted the heterogeneity in household vulnerability patterns within and across communities. Failing to account for this heterogeneity in adaptation planning might result in a mismatch between adaptation needs and interventions, and potentially in maladaptation.